Issuu

July 2026 Transit Trekking Travelling with the Perth Observatory cap!

Itsy Bitsy Spider What's in the Tarantula's name?

Magnificent Meteorites The wonderland and wonder of impact craters

Cascades of Colours A deep dive into the Hertzsprung-Russell (HR) diagram

THE PERTH OBSERVATORY MAGAZINE 1

'Society’s future will depend on program for the human charact bring? I do not know, but it will ―Neil Armstrong

a continuous improvement ter. And what will that future be exciting.'

Image: Soccer Meets Space Science Image Credit: NASA

Contents

6 A View Through The Eyepiece 10 Perth Sky Update 18 30 Doradus 24 Starry, Starry Nights in the Pilbara

36 A Tale of Two Transits 40 HR Diagrams 48 Volunteer Spotlight

Find Us Here

58 A Meteorite Impact Structure Wonderland 68 Project Hail Mary 74 What's On In July's Skies 76 What's On In August's Skies

78 What's On In September's Skies 80 Amatuer Astronomer Cheat Sheet 81 Crazy Cursors

68 Editorial

Contributors

Subscriptions

Lousie Kaestner Editor Typesetting Graphic Design

Click below to subscribe Michael Davey, Paul Fisher, Arthur Harvey, Louise Kaestner, Andre Lake, to our newsletter Mara Leisavnieks, Julie Mathews, Siobham Nims, Kaylan Reynolds, Sandra Tinari

Front Cover Image By Joel Brajkovich Back Cover Image By Roger Groom Newsletter Icon by Rawpixel.com at Freepik

A View Through The Eyepiece

Greetings, Earthlings! Breathe in. Gaze up at the vast night sky through the dense clouds. Stars twinkle, peeping through the cover. A wayward raindrop plonks onto your forehead. For 60,000 years, the Whadjuk People of the Noongar Nation have been watching the Dark Emu, our constant winter companion. We are incredibly blessed to be able to witness the same Dark Emu today at the Perth Observatory in Bickley. We’ve got an action-packed magazine issue for you with some new voices splashing onto our pages and old voices making sure we keep tracking well. Michael Davey reveals the spectrum on Hertzsprung-Russell (HR) diagram. Kaylan Reynolds shares his proud moment of graduating from trainee to Amateur Astronomer on the Howard Grubb Astrograph. Mara Leisavnieks takes us on a journey to the Pilbara and Andre Lake takes us behind the scenes on where the Tarantula Nebula got its name. Please send your shout out submissions for the newsletter. We want to share with everybody the beautiful volunteers of the observatory and what they are up to. Recognition rules. Finally, submissions are always open, and I will hunt you down for your piece. We are looking for anything space, astrophotography or Perth Observatory related. So many of you share your pictures during a session. It would be great to showcase them in an issue. Submissions can be sent to lcmckwd@gmail.com at any time. I can be reached on 0466788697. Please, only text me.

Louise Kaestner Editor

Image: The Helix Nebula NGC 7293 Image Credit: NASA

Upcoming Don't Miss Out. Events: Book Now! 31st of July Paint and Sip Time: 6:30 pm - 9:30 pm (Doors open at 6 pm) Price: $126.25 per person As the evening says, you start out with a sip, end up with a paint and stare at the skies in wonder and faint. There will be wine, nibbles and painting. While you are waiting for your masterpiece to die, you'll get an exclusive Night Sky Tour and gaze at a minimum of 4 out of this world objects.

Image: pngtree.com

5th of AugustAstronomy 102 Course Time: 7 pm - 9:30 pm (Doors open at 6:30 pm) Price: $300 per person Curious about the vast expanse of space? Launch yourself into our 5-week astronomy 102 course run by the esteemed Jenny Gull. We cover a range of topics including light, astrobiology, galaxies, the physics of stars and the Big Bang.

Image Credit: brgfx at Freepik

Image: Moons, Rings, Shadows, Clouds: Saturn (Cassini) Credit: NASA, JPL-Caltech, Space Science Institute

Perth Sky Update: From Vision to On-Site Reality by Sandra Tinari Image credit: Sandra Tinari

After more than a year of steady progress, the Perth Observatory’s Perth Sky Sculpture Park is entering a defining phase as the project transitions from planning into physical delivery across the site. Many within our volunteer community have been part of this journey. What is becoming increasingly clear in 2026 is not just the strength of the original idea, but the scale, pace and professionalism with which it is now being realised. With the official opening date confirmed for 31 October 2026, Perth Sky is no longer a future vision — it is an active build toward a major new day-time cultural offering at Perth Observatory, which will help to diversify our activities, engagement with the community and stakeholders and our revenue streams. A Year of Momentum and Milestones The first quarter of 2026 has marked a significant acceleration across all areas of the project. A major milestone has been the national and international artist call-out for the Perth Sky opening exhibition, following the completion of artist information packs and a targeted outreach campaign spanning WA, interstate and global audiences through database marketing, press advertising and social media campaigns. The response has been exceptional: • • • •

More than 120 small and larger outdoor sculpture submissions received with around 60 selected. 90 indoor small work sculpture submissions received with around 45 selected. Artists represented from Western Australia, across Australia and internationally Many responded to the POVG’s mission with artwork themes of science and the cosmos.

For a first-time exhibition, this level of engagement signals that the POVG’s Perth Sky is already being recognised as a credible and ambitious platform for contemporary sculpture with the potential to significantly contribute to Western Australia’s cultural landscape.

At the same time, team governance has strengthened, with the expansion of the planning committee and the confirmation of a highly credentialled curatorial selection panel, including: • • • • • • •

Gemma Ben-Ary (City of Kalamunda Arts Officer) Kate Parker (Senior WA Public Art Consultant and Architecture Urban Design Lead at SLR Consulting) Sharyn Egan (Senior Noongar Artist & Cultural Advisor) David Horton (Head of Sculpture, National Art School Sydney) Johannes Pannekoek (POVG volunteer: Chair & Head Curator Perth Sky) Sandra Tinari (POVG Volunteer: Creative Director) Sam Hopkins (Artist and Sculpture Installer)

Volunteer-Led, Enabled by City of Kalamunda funding Perth Sky is a volunteer-led initiative, developed by the Perth Observatory’s Perth Sky volunteers—a group of local artists and arts-destination professionals working to expand the Observatory’s day-time experience. A critical enabler has been the financial generosity of the City of Kalamunda, following a formal funding request from this volunteer group. This support was realised through direct funding and by the City’s purchase of two donated artworks via its developer-funded public art program. These works will enter the City’s collection for display and long-term public benefit, while directly enabling the creation of the Perth Sky Sculpture Park. This early backing has proven catalytic—transforming a bold idea into a fast-advancing regional project that supports cultural tourism, place activation, community participation. This backing will help to expand and strengthen the Perth Observatory’s importance for Western Australia, making an already great destination even greater.

Designing the Daytime Experience at Perth Observatory Perth Sky is designed to complement Perth Observatory’s established night-time programs by introducing a curated daytime visitor experience incorporating art, heritage and nature. Current work is focused on how visitors will move through and engage with the site, including: • • • • •

Finalising the proposed sculpture trail across the Observatory grounds. Mapping artwork locations in response to landscape and heritage features. Assessing each work for engineering, safety, and installation requirements. Coordinating artist fabrication, freight and installation timelines. Tusk Installation: Installing the first of the donated artworks purchased by the City of Kalamunda, which will be displayed on loan at the Perth Observatory for an initial period. This sculpture, entitled ‘Tusk’ was donated by renowned New York artist, John Clement. Clement’s work is internationally collected and is located internationally in high profile public locations. See the artists work and further information here. Tusk is a vibrant yellow sculpture, that was refurbished and bought back to life by our volunteers.

The aim is to create a journey where artworks are encountered naturally through existing bushland paths, open sky and the Observatory’s historic setting. This represents a significant evolution for Perth Observatory, strengthening its role as a daytime tourism destination, while encouraging new visitors to return for its evening programs.

The inaugural Perth Sky Exhibition & Acquisitive Awards will open the Park on 31 October and include: • • •

Outdoor sculptures of various sizes installed across the grounds for up to 22 months. A Small Works Exhibition for two weeks inside the main building, offering a more intimate viewing experience. Sculptures across both categories available for sale, with commission reinvested directly into the maintenance and operations of the site.

Together, these elements create both an immediate exhibition moment and a lasting cultural layer embedded within the Observatory landscape. Behind the Scenes: Complex Delivery Underway This includes: • • • •

Engagement of site logistics and installation specialists. Coordination of sculpture installation across the park. Development and printing of a visitor guide, connecting Perth Sky with the heritage and science story of the wider Observatory. Planning of the official opening event and public program.

The project continues to operate with the discipline of a cultural start-up, combining volunteer energy with professional expertise.

Community Partnerships Bringing It to Life Community contribution is playing a tangible and visible role in shaping the visitor experience on site. •

•

Perth Sky’s team secured supported from Rotary Kalamunda, with fabrication support from the Kalamunda Men’s Shed. They are delivering beautifully crafted outdoor bench seating at the POVG, enhancing comfort and accessibility. Design is complete and the hand-crafting of the benches by the Men’s Shed is underway. This represents a significant donation of plus $30,000 to the POVG. KTrans has confirmed sponsorship support for logistics and transport, assisting with the movement and installation of sculptures from interstate to the Perth Observatory to the value of $40,000.

At the same time, the expanded Perth Sky planning committee continues to grow capacity across finance, operations, curation, installation and events—ensuring the project is supported by the right mix of skills as it scales. Looking Ahead: From Planning to Presence The coming months mark a clear transition point. With planning underway since March 2024, Perth Sky is now moving into physical presence on site: • •

Sculptures will begin arriving from winter onwards. Installation will commence.

Looking beyond October Planning is already underway for: • • • •

Artist residencies and education programs. Ongoing site maintenance. Future exhibitions and public programming. Long-term sculpture sales and commissions with the funds reinvested back into the POVG, site operations and maintenance.

A Collective Effort Worth Recognising Perth Sky represents something significant for Perth Observatory. It is: • • •

A Perth Observatory initiative driven by volunteers. Funded through the generosity of the City of Kalamunda. Supported by a growing network of partners, artists and community organisations.

The initiative is always on the search for more support—if you’d like to help or know of potential volunteers, please do let Nadia know! As the countdown to 31 October 2026 continues, Perth Sky stands as a powerful example of what this community has built together, transforming a shared idea into a real, visible and lasting addition to the Perth Observatory’s daytime experience.

Contact 14

Image: Yoda meme Image Credit: Imgflp

Image: Clouds against a night sky Image Credit: Google AI Mode

Image: Beacon of Light Image Credit: NASA

30 Doradus: NGC 2070 by Andre Lake GradCertSc (Astron) '...along came a spider...' —unknown authorship (1805) Who nicknamed 30 Doradus the Tarantula Nebula? This turns out to be a much harder question to answer than you’d think. It was a question asked by a Night Sky Tour guest, and as expected, one of the younger members of the group. A curve ball question, that I had no answer for. The ‘why’ it was unofficially labelled ‘Tarantula’ is something we can all parrot out in google search fashion ‘because its bright, dusty filaments, captured in long-exposure telescopic images, resemble the legs and spindly appearance of a spider.’ Furthermore, the general answer is that “the scientific astronomical community adopted the epithet, over a vague period somewhere between 1950 and 1960”. To me that sounds like a cop out. There must have been a first someone. To quote John Farnum, ‘One man to start the trouble…'1, bringing the question back to, who? The ‘who’ however is something even google doesn’t know. I’ll spare you the pitiful google response. Most people would guess it was John Herschel. Most people would be wrong. Herschel called it ‘the Great Looped Nebula’ for the similar reason of curly filaments, which led to the arachnid reference. Overall, the historical records related to this question are, generally non-existent. We do know that in 1801 Johann Bode2 catalogued it as 30 in the constellation Xiphias or Dorado3. Admiral William Henry Smyth, referred to 30 Doradus as ‘the True Lovers Knot’ in 1844. As mentioned, J. Herschel had his great loops, but the Tarantula seems to have crept in unannounced. Not wanting to be beaten so easily, I decided to look at this from a different angle. That being ‘when’ did it first appear in scientific publications? Then I thought I could narrow down the culprit by identifying the authors. Or woman. The guy who renamed Georgium Sidus, Uranus. To the amusement of nine-year-olds, both big and small. 3 The Swordfish, or the goldfish, or the Dolphin fish. Dorado means gold in Spanish, Xiphias means sword in Latinised Greek. In the Netherlands Dorado is the goldfish. There is also a fish called a Dorado (dolphin fish). Image: Squatting Tarantula in Space Image Credit: Google AI Mode 1

The ‘when’ it turns out is not much easier to figure out. The ‘Tarantula’ monicker doesn’t appear in scientific papers until the 1960’s. In fact, from personally reading a fair sample of those produced around this time. It seems likely, that the ‘Tarantula’ naming became ‘a thing,’ somewhere between 1961 and 1968. The two most likely sources of research during that period, related to 30 Doradus and the Large Magellanic Cloud (LMC) in general are the Radcliff observatory in Pretoria South Africa, Mt Stromlo Observatory in the ACT1 or later on in Siding Spring NSW. Being a big fan of the research and the researchers at Mt Stromlo/Siding Spring, I immediately assumed it was one of the more well-known researchers, at either place. Names like Bart Bok and S. C. B. Gascoigne2 seemed plausible as did the other 16 or so researchers active between 1960 and 19753. But, of course, Radcliff Observatory was in operation before Mt Stromlo and had just as many big names in the 1950’s and 1960’s, such as A. D. Thackery, M. W. Feast and A. J. Wesselink4. Radcliff was funded by Harvard and Oxford universities, and it had an association with the Lowell Observatory in Flagstaff Arizona5. When it came to southern hemisphere observations, Radcliff was the top facility.

Image: Tarantula Nebula (NIRCam image) Image credit: NASA, ESA, CSA, STScl, Webb Ero Production team (PD) The currently famous South American Observatories were still either being planned or under construction. With the exception of Cerro Tololo which early on, was involved in other observational research. 2 Bart Bok and S. C. B. Gascoigne are my favourite astronomers, from back when I was ten years old, when I read books like ‘The Southern Universe’ by Lennard Bickel. A book which I still own. 3 Including Bart Bok’s wife Priscilla. She was responsible for a lot of the photographic interpretation and was a respected astronomer in her own right. 4 Not to be confused with B. E. Westerlund, like I often have in the past. 5 Just like Perth Observatory back in the day. 1

The naming for example of R136 originally RMC1361 is a Radcliff designation. The R stands for Radcliff. The first discovery of and subsequent research of R136 and of course the identification of R136a1 and R136a2, etc., was at Radcliff. Although Mt Stromlo and Siding spring observatories were involved and continued this work, after Radcliff was closed and the facility grounds, were given to South African military intelligence2. I digress. Unsurprisingly, the scientific papers about 30 Doradus, from 1960 to 1969, are more commonly authored by Radcliff Astronomers3. The main suspect in fact being Professor Michael William Feast (1926 to 2019), he was at the Radcliff observatory from 1952 until 1974 and wrote several scientific papers on the LMC and R136, as well as Luminous Blue Variable (LBV) and Wolf Rayet stars related to 30 Dor and the LMC in general. I was pointed in the direction of M. W. Feast after I emailed this question to one of the writers of the now discontinued Astronomy Australia Peter Northfield. He also happens to be a really nice bloke. Peter’s reply referred to …‘Jeff Kanipe's Annals of the Deep Sky, Vol 9 (2023). I quote from page 334.’

"The name ‘tarantula’ arose in the late 1950s and early 1960s after photographs made with large-scale reflecting telescopes revealed the nebula's complicated internal structure, which some authors said resembled a tarantula (Feast 1961). It was also sometimes referred to as the ‘Loop’ nebula by Shapley and others. In the end, the arachnid appellation won the day, although, frankly, I don't see it." ‘The reference he made (Feast 1961), I believe, refers to Michael William Feast (1926– 2019), a British-South African astronomer. I don’t have access to any of his papers to check.’….4 (end of Peter's response).

RMC – is an acronym for Radcliff Magellanic Cloud. Referring to objects studied in either the LMC or the Small Magellanic Cloud (SMC). 2 Why this happened is a “cold war’ mystery, for another day. (see references Glass L. S.,) 1

3 4

Although some of the guys and girls from Mt Stromlo spent short periods of time at Radcliff. Excerpt from Peter Northfields email to me.

Image: Oil Painting of Tarantula Image Credit: Google AI Mode

Well, I checked M. W. Feast’s papers. Havard Astrophysics Data System (ADS) and SIMBAD Astronomical Database got a thorough searching. I have now read a lot of his Monthly notices to Royal Astronomical society and twenty or more of his papers, including those he contributed to. I read his Wikipedia entry and even his obituary. He might be the guy. However, definitive proof still alludes me, since that paper referencing ‘some authors’ was actually written by M. W. Feast himself1. Who was he referring to, or was this just a sideways personal plug for his own work? The name ‘Tarantula’ is now endemic throughout any publication about 30 Doradus, be it for the general reader, the latest scientific offering to be found on Arxiv or Harvard ADS. Robert Burnham, within the three tomes of ‘Burnhams Celestial Guide’, refers to 30 Doradus as Tarantula, in such as casual manner that it seems to have been normalised by 19772. I have often offered a reward of five dollars of my own money, to anyone who can name, the person(s) responsible and can prove it. So far, no one has come forward. For now, then, the Tarantula can scuttle off to the corner and hide behind that loose piece of carpet. It seems happy in its cognomen of anonymity.

Image: Abbé Nicolas-Louis de Lacaille who recognised 30 Doradus as a nebula. Image credit: Melle Le Jeuneux - Stoyan R. et al. Atlas of the Messier Objects: Highlights of the Deep Sky.

1 2

Referenced paper 1961MNRAS.122….1F (S.C.B. Gascoigne is directly referenced in the text) Burnhams Celestial Guide, Volume 2, page 848, The Tarantula Nebula

References (for brevity not the complete list)

•

Burnham R., “Burnhams Celestial Guide, Volume 2, Chamaeleon Through Orion”, pg. 848.

•

Bickel L., “The Southern Universe”, Macmillan 1975, ISBN 0 333 17578 6. (Awesome pictures, no photoshop back in 1975.)

•

Feast M. W., “A study of the 30 Doradus region of the Large Magellanic Cloud”, Monthly Notices of the Royal Astronomical Society, Vol. 122, No. 1, (Communicated by the Radcliff Observer), (Received 1960 August 3), 1961MNRAS.122….1F

•

Feast M. W., “Interstellar Lines in the Nuclear Star of the 30 Doradus Nebula”, December 1953, Notes from Observatories, 255, 1953Obs…73...255F

•

Feast M. W., et all, “A Study of the Bright Members of the Magellanic Cloud”, 216 Bright members of the large Magellanic Cloud, No. 888, 1950Obs…75.216F

•

Glass L. S., “Andrew David Thackery at the Radcliff Observatory”, South African Astronomical Observatory and Centre for Astronomy, James Cook University, Townsville, Queensland, Australia., April 13, 2009.

•

Jones K. G., “The Search For The Nebulae – VI”, 1969 JBAA…79

•

Westerlund B. E., & Smith L. F., “Wolf Rayet Stars in the large Magellanic Cloud” MNRAS (received 1964 Marcg 10), 1964MNRAS. 128..311W

Image: Tarantula Steampunk Style Image Credit: Google AI Mode

Join our School Day Tours Team Looking to volunteer and make a difference in the lives of primary school children? If you have free time during the day and a passion for learning about space and our solar system, we invite you to join our School Day Tours Team as a volunteer! As a member of our team, you will have the opportunity to share your knowledge and enthusiasm with young students while learning from experienced educators. No prior experience is necessary, as we provide all the training you need. If you enjoy working with children, this could be the perfect opportunity for you! All you need to bring is your enthusiasm, a friendly demeanour and the ability to communicate with children. To learn more about how you can get involved, click below and let’s start making a difference in the lives of young students today.

Image: Karntama Viewing

Starry, Starry Nights in the Pilbara Story and Photos by Mara Leisavnieks I’m an amateur astronomer volunteer with the Perth Observatory and recently was lucky enough to do an offsite star gazing visit in the Pilbara. The Fortescue Mining Group Cloudbreak and Karntama Village mining camps near Nullagine were the setting. For those who indulge in social media, you would be aware of ‘expectation vs reality’. OK, this was the expectation: • • • •

Provide driver’s licence for ID purposes 2-hour flight from Perth to Cloudbreak with a Dobsonian telescope and Seestar s50. Stay 2 nights at Cloudbreak Village and conduct a 2-hour session on the oval for the first night there. Then the same for the second night at Karntama Village approximately 25km away. Finally, returning to Cloudbreak that night. Transport to Christmas Creek airport next morning for the 2-hour flight to Perth.

I was looking forward to this opportunity to share the wonders of the night sky with those who do long shifts in often harsh conditions. The reality was far more interesting and memorable. It went something like this: • • • • • • • • • • •

Attend a full functional fitness test, fill in medical questionnaire and endure an assessment by a doctor. Pick up the large bag and carton containing the Dobsonian telescope and its stand, peripherals and Seestar s50 with tablet from the Observatory. Get up at 4am to go to the airport for a 5.55am departure. Check in telescope and stand in oversize baggage and have breakfast in the Qantas Club (glad I kept up my membership after retiring from work!). Board a Fokker 100 aircraft, slight delay while engineers check an issue. Depart 15 minutes late, doze off until 35 minutes after departure when the crew announce that coffee and refreshments will shortly be served. 40 minutes after departure, the captain advises we must return to Perth due to a technical issue. Safely land and revised departure time is now 9am (could have had a sleep in!). Depart Perth in a different Fokker 100, doze some more until crew announce coffee and refreshments will be served. Second announcement 2 minutes later advising the coffee station is out of order, only refreshments will be served. Luckily, we won’t have to go back to Perth for this malfunction. Arrive safely at Cloudbreak 3 hours later than originally planned.

On arrival, I was greeted by Toni, the Health and Wellbeing Coordinator (HWC), and after being shown around and getting some lunch, I went to check out the oval where the star gazing would occur. I was hoping the surrounding lights would not interfere with the viewing. Back in the accommodation, I got the tools out and put together the base for the telescope. Second announcement 2 minutes laterImage: advising theNebula coffeeM42 station is out of order, only Background Orion's refreshments will be served. Luckily, we won’t have to go back to Perth for this malfunction. 25

Around 5.45pm Toni arrived to help transport and set up the telescope and Seestar s50 on the oval. Groups would come through for viewing every half hour from 6.30pm to 8pm. I pointed the 8-inch telescope towards Jupiter to focus it and have it ready for the first group. No matter what I did, I couldn’t get a crisp image while adjusting focus on the 25mm lens. I checked the telescope to make sure the mirror and other parts were not damaged. I changed to the second lens and voila! Jupiter and the 4 main moons came into crisp view. Phew! Meanwhile, the Seestar wasn’t having a bar of it, refusing to get GPS coordinates and asking for a reset. I did a reset, it still didn’t want to find where it was, even with me trying to manually input the coordinates. I was starting to think I was in a Bermuda triangle situation. I have my own s50 and have gone to different locations and never had it ‘spit the dummy’. I shut it down. As it was almost 6.30pm, just went with the telescope. 35 interested people came along over the next two hours to view and learn about Jupiter, Alpha Centauri and the Jewel Box open cluster. I was limited in what I could show because we were surrounded by blazing floodlights which couldn’t be turned off. Everyone still enjoyed the experience learning about the night sky. I showed them how to find the south celestial pole, talked about the moon, how far away objects really were and the reality of trying to traverse over 40 trillion kilometres to get to our nearest stars. Quite a few people downloaded the Stellarium mobile app. There was a lot of interest in smart telescopes. I had my tablet with me and was able to show participants some interesting deep sky objects previously captured with the Seestar and how easy the process is to find objects. The Orion nebula was a crowd favourite. I loved the interaction and interest shown by all on the night. Everything had to be dismantled and repacked at the end of the night as Cherie (Cloudbreak Village Supervisor) said I was now going to go to and stay at Karntama Village the next day. I did some troubleshooting of the Seestar when I got back to my accommodation and finally got it working properly. After a hearty breakfast, I was picked up mid-morning and taken to Karntama Village which is near the Christmas Creek mine. Jessica (HWC) arrived to check me in, gave me a tour, made sure I got some lunch and took me to my accommodation. I put together the base once again in readiness for the night viewing. The oval here was in a better location being at the edge of the village. I did a check with the Stellarium app to see where the best spot would be to set up to view the Moon, Jupiter and other objects later. 5.45pm saw Jess and Ihead off to the oval to set up. She said that they were expecting around 50 people to attend for the 4 sessions. Everything went smoothly this time. The telescope was set up on the Moon as we had almost a quarter showing. It would only be good for the first 10 minutes before disappearing behind trees but would allow for some viewing. Jupiter was sitting nicely to take over. I managed to show Alpha Centauri, Jewel box, Eta Carinae and moved to Sirius and Herschel’s lovely double (145 Canis Majoris) when some clouds rolled in.

Background Image: Cloudbreak Village

The Seestar behaved itself and I set it to capture Eta Carinae and the surrounding nebulosity. The participants were able to see the difference between what the telescope showed and what the Seestar could capture. The telescope view was the main binary stars (not able to separate the two) with a bit of pale white ‘haze’ around it. The Seestar showed lots of gas and dust of surrounding nebula. I also demonstrated how it moved to objects by selecting the Southern Pinwheel galaxy. From almost nothing, it started ‘appearing’ after the first minute. Once again, downloading Stellarium and interest in smart telescopes was quite popular amongst the groups. When I mentioned on both nights that the Seestar smart telescopes cost less than $1000AU, there were a lot of surprised looks. Most thought they would cost a lot more. I encouraged all on both star gazing nights to check out the Perth Observatory website, book and come along for a night sky tour or special event, or if they were interested, look at becoming a volunteer with us. After packing up, it was time for sleep as I had to get up at 5am to have breakfast, check out and be ready to catch the bus to the airport to return to Perth. I can happily say the aircraft was fine, the coffee station was working and we landed on time. A big thank you to Matt (Perth Observatory), Cherie, Toni and Jessica for the opportunity to share the night sky and looking after me. I hope I can get to do this again in the future. Wishing you all clear skies.

Background Image: Stargazing Sign

Image: The Black Eye Galaxy Image Credit: NASA

Telescopes Under Western Australia’s Skies

Looking for an unforgettable night under the stars? Look no further than Perth Observatory’s offsite astronomy nights! As Western Australia’s leading Observatory, our experienced volunteers are dedicated to sharing the beauty and wonder of the night sky with people across the state. Our team will bring their top-of-the-line telescopes and expertise to your town, suburb or school, providing you with a unique and immersive journey through the Southern Hemisphere’s celestial wonders. We will also guide you through the night sky with the help of our green lasers, teaching you about the stars, planets, nebulas, dying stars and enormous star clusters that populate our universe. Whether you are an astronomy enthusiast or simply looking for a fun and educational experience, our offsite astronomy nights are the perfect way to explore the beauty and complexity of our universe. Request your night under the stars below and discover the magic of Perth Observatory!

Kaylan Reynolds. Why? For being the second trainee to graduate on the astrograph! Lindsey jones. Why? For being an amazing day time gatekeeper of the universe!

Kyna Shrick. Why? For being the youngest host ever!

Matt mulder. Why? For being a long time volunteer! Jenny Mikucki. Why? For writing the grants that bring in the additional funding that keeps our lights on!

Image: The Howard Grubb Astrograph Perth Observatory Image Credit: Norma Bertram

Graduating to AA by Kaylan Reynolds

Image: Kaylan Reynolds setting up the 16-inch Meade Image Credit: Louise Kaestner

After being an active trainee at the observatory for over 6 months, numerous suggestions were made to me that I should stop slacking off and graduate as an Amateur Astronomer (AA). This spiel is, therefore, not so much about how I’m the most brilliant and motivated astronomer out there; rather, it’s dedicated to those who willingly got the ball rolling for me time and time again…and time and time again.

My first nights at the Perth Observatory were certainly unique in the sense that I attended 10 or so training nights before I even stepped foot in a Night Sky Tour (NST). Now the precise reason for that might be publicly stated as, ‘I wanted more practice and technical knowledge before I gave presentations,’ though I will neither confirm nor deny if it was to spend time with a girl I would go on to date later on… you didn’t hear that from me. Nevertheless, those nights were incredibly insightful under the guidance of Steve Webb, an absolute legend regularly soloing the Wednesday training sessions. Steve initially, and continues, to go out of his way to send me informative messages, offer training and provide motivation, allowing me to become proficient in both the Astrograph and 16-inch. In terms of the success of our trainees, the observatory is extremely fortunate to have Steve spearheading Wednesday night sessions.

My first tours were spent in the Astrograph dome, diving in headfirst on a Full Moon Tour—co-presenting with Steve. After trying to snag a spot on the same telescope during a particular NST, I noticed that Louise Kaestner fought for the Astrograph just as hard as me. I was fortunate enough that, although they won the ‘graph that night, I continued to witness one of the most exciting and brilliant presenters the observatory has to offer. For the sake of preserving that idea… I won’t provide the video of their ‘Vogon Poetry’ during the Towel Night Sky Tour, for it was truly torturous. For all future trainees, it’s important to mention that although telescope operation is pivotal to your role as an astronomer, spending tours watching and observing other volunteers is just as important. Establishing a mental ‘library’ of diverse presenting techniques will benefit you greatly—both as a trainee and an AA later.

I guess to touch on the weirdness of my path to an AA, my graduation came during the Innovator’s Tea Party Exclusive Night Tour. Initially short-staffed, I dual-wielded the Astrograph and 16-inch domes, setting both up under the supervision of Louise. If that wouldn’t induce stress on you enough, Louise also invited my family to observe my presentation in the Astrograph afterwards. Along with another trainee Jason, we manoeuvred the telescope from the Jewel Box to the Southern Beehive—ending the night by eyeballing moon and setting it against the interchangeable opaque plate.

Upon writing this, I’ve become a fully-fledged AA participating in outreach tours and regular NST events. This speal would hardly be complete without a quick thanks to Nadia, our irreplaceable Volunteer Engagement Officer. From inadvertently positioning me in work experience to being a friendly face as a new trainee—Nadia, you’re awesome. A massive thank you to every other trainee who helped me along the way; you’re all amazing. Image: Cinematic Moon Image Credit: Google AI Mode

Image: Orion Nebula Credit: Joel Brajkovich

A Tale of Two Transits … by Arthur Harvey Images supplied by Arthur Harvey

‘Have Perth Observatory cap—will travel’ We all know that in 1769 a certain sailor sailed a certain ship halfway around the world to observe a certain transit of a certain planet across the face of our star. This is not about that transit. But the same sailor, sailed the same ship eastwards until he made landfall in Aotearoa; the Land of the Long White Cloud. There, at Mercury Bay on Nov 9, 1769, he and Astronomer Charles Green observed a transit of Mercury.

Transits of Mercury are more common than those of Venus; they occur about 13 to 14 times per century. Commemorations of this event commonly refer to it being significant insofar as it enabled Cook to determine his longitude. However, Cook’s log does not specially mention the transit being used for this purpose. Green did not survive the voyage and some of his papers have been lost. Modern historians accept that Cook’s used other methods, and particularly the ‘lunar distances’ technique, to determine his longitude. It’s worth taking a closer look at what happened. Here, I refer to Bill Keir’s paper entitled ‘Captain Cook’s longitude determinations and the transit of Mercury— common assumptions questioned.’

Keir notes that on 3 November, Green logged five lunar distance measurements taken over a period of about 25 minutes around 3 pm (Wales Citation1788, 43). The ship was then at sea about 10 kilometres east-southeast of the south head of Mercury Bay. These observations yielded a mean longitude for the ship's position of 175° 37′ E. Today's value for the same position is 175° 53′ E. It is clear from these records that when Cook entered Mercury Bay on 3 November he already had a good grasp of the longitude from his position history over the previous two weeks to an accuracy within the uncertainty range he would have expected (+/- 15 arcminutes). Tripping between transit locations we passed through Napier where we spotted the Kirk sundial. Somewhat the worse for wear and with three mottos, it was erected after [and mounted upon rubble from] the 1931 earthquake. ‘Time is swift, much is to be done’.

After Cook’s observation of the transit of Venus, the next transits were in 1874 and 1882. By that time photography has been applied to astronomy and was used to take pictures of the transit. As before, the main purpose was to refine the measurement of the AU, the distance from the Earth to the Sun. A US expedition to Queenstown in the South Island of NZ was one of many sent to observe and record the transit. [Imagine the coincidence of looking out our Queenstown hotel window and seeing the commemoration cairn for this event!]

The Queenstown transit team was led by Chief Astronomer Dr C H F Peters. The fixed horizontal telescope known as a photoheliograph, in which a weight-driven heliostat directs the Sun’s rays through a lens, which focuses the image onto a photographic plate 38.5 feet away. This method was used by American and French observers. The photographic method required the evolving angular distance between the centres of the Venusian and solar discs to be measured. This would yield the angular distance of closest approach, which like all transit phenomena, is affected by parallax. Values from different sites would then yield the solar distance.

A total of 237 photographs were obtained, 178 of the ingress contacts and 59 of Venus on the Sun's disk (Newcomb Citation1881:439–440). Observing with the Clark refractor, Peters obtained a series of micrometric measures of Venus's position relative to the Sun's limb. Orchiston concludes ‘The 1874 and 1882 transits of Venus ‘marked the end of one astronomical era and the birth of another. They were the last transits used in a serious attempt to resolve the solar parallax problem, before other methods gained favour. They also marked the first internationally co-ordinated assault on a major astronomical problem using the emerging technology of photography.’ To be able to place yourself at the exact locations of historical, scientific [and military] events hold a certain fascination for me so to be able to stand near the site of not one but two transit observations in NZ was an opportunity I did not miss!

Image References: • • • •

Image of Captain Cook taken at the Cook Lighthouse, Auckland. Image Dimensional sketch of HMB Endeavour by Francis Joseph Bayldon. Reference: “The 1874 transit of Venus: New Zealand's first foray into international astronomy.” W Orchiston.

HR Diagrams …not so scary

Article and images supplied by Michael Davey 40

When I first looked at an HR Diagram, I was a little intimidated—lots of dots, numbers, a strange letter system and a pair of axes that made no sense. Thankfully, I had a few very patient people to explain it to me. The Spectral Class—What’s along the bottom? First, let’s get some basics done. When we heat things up, the colour changes— starting from red all the way to blue—just like a gas stove top is hotter than a candle. For those interested, this is known as Wien’s Law. Stars are no different and the fancy name for this temperature-colour system is the Spectral Class (the letters along the horizontal axis, at the bottom of the diagram). But what’s with the letters? In the 1880s, Williamina Fleming classified stars based on the strength of the hydrogen absorption lines (lines observed by looking at the ‘spread’ of starlight). However, when a star is very hot (like a blue star), the lines in the visible spectrum weaken or change, so a new system needed to be developed. Annie Jump Cannon revised the system in the early 1900s by classifying stars by their temperature. Instead of redesigning a whole new system, Annie simply rearranged the old one. So instead of a normal alphabetical sequence, we now have: O, B, A, F, G, K, M. A very accomplished astronomer, Annie classified over 500,000 stars in her lifetime! So, we now have a system of classifying stars by their temperature, starting with O (Blue stars), which are the hottest, all the way to M (Red stars). The number after the letter in a subclass also relates to temperature. For example, a B0 star is hotter than a B9 star. In summary: letters denote the broad temperature group, and the number refines it further. Stars are hottest at Blue (O) and get progressively cooler all the way to Red (M).

Note: The letter K denotes the temperature unit, Kelvin. 0˚ Celsius = 273 Kelvin.

Luminosity—What’s up the side? So, we’ve sorted the horizontal axis, which shows us the temperature of stars—hot on the left as a Blue (O-type) star, getting cooler as we move to the right toward Red (Mtype) stars. Now let’s look at the vertical axis: luminosity. Luminosity is simply how much light a star produces. As you might imagine, the further a star is from Earth, the dimmer it appears—but that’s our problem, not the star’s. (This is known as the Inverse Square Law for those interested.) Think of a torch: luminosity measures how much light the torch is producing, not how bright it looks from where you’re standing. The scale of luminosity is enormous, spanning from stars hundreds of thousands of times brighter than our Sun, all the way down to stars barely keeping the lights on. To compress this huge range onto a page, we use a logarithmic scale (each step is a big jump). Don’t worry about the maths, just remember up = bright and down = dim.

Putting it all together Around 1910, two astronomers independently had the same idea: what if you plotted every star on a graph with temperature on one axis and luminosity on the other? Ejnar Hertzsprung in Denmark and Henry Norris Russell in America did exactly that—and what they found was remarkable. Instead of a random scatter of dots, the stars arranged themselves into distinct groups. The diagram was named after both of them: the Hertzsprung-Russell Diagram, or HR Diagram for short. A star’s position on the HR Diagram is mainly determined by two things: its mass and its stage of evolution. Given that much of the foundational classification work was done by Fleming, Cannon and their colleagues at Harvard Observatory—often working as ‘human computers’ at a time when women were rarely given full credit—it’s worth noting that the HR Diagram truly stands on the shoulders of some very talented women.

The Main Sequence The main diagonal band running across the diagram is known as the Main Sequence. It’s simply where a star spends roughly 90% of its life, happily fusing hydrogen into helium in its core. Along the main sequence, the hotter the star, the more luminous it tends to be—which is why the band runs diagonally from hot-and-bright in the upper left, down to cool-and-dim in the lower right. Our Sun sits comfortably in the middle of the Main Sequence, and has been there for about 5 billion years, with another 5 billion or so to go. Once a star runs out of hydrogen fuel in its core, it is said to ‘move off the Main Sequence’ and follows a sequence of events depending on its initial mass. The groups of stars to the upper right (giants and supergiants) and lower left (white dwarfs) of the Main Sequence tell the story of where stars end up. To explain this, let’s look at two very different examples.

Betelgeuse—A life lived fast Not to be confused with the legendary 1988 film, Betelgeuse sits in the Orion constellation and can easily be spotted as the red/orange star beneath the ‘shopping trolley’ asterism. It is one of the largest and most luminous stars visible to the naked eye. Betelgeuse likely began life as a very hot, blue O-type star or early B-type star, 16 times more massive than our Sun, furiously burning through its hydrogen fuel for about 8 million years on the Main Sequence. About 40,000 years ago (roughly the Stone Age here on Earth), Betelgeuse ran out of hydrogen fuel in its core, cooled down, and ‘moved off’ the Main Sequence. As it cooled, it lost its blue colour and ‘puffed up’ into the enormous red supergiant we see today. This is why Betelgeuse plots in the upper right of the HR Diagram—still enormously luminous, but noticeably cooler and red. Inside, the situation is urgent. Having already burned through its hydrogen, Betelgeuse is thought to be in a late stage of stellar evolution, likely burning heavier elements beyond helium. Each successive fuel burns faster: from millions of years on hydrogen, to thousands on carbon, to potentially just weeks on silicon before the core becomes iron—at which point fusion stops, the core collapses in less than a second, and the result is a supernova. When it goes, Betelgeuse will be visible in broad daylight and bright enough to cast shadows at night—a once-in-a-civilisation event. Astronomers consider it one of the best candidates for the next galactic supernova (a supernova inside our own Milky Way, as opposed to those we regularly observe in distant galaxies). The last one seen from Earth was in 1604, observed by Johannes Kepler. Note: Betelgeuse is about 700 light-years away, meaning the light we see left the star around the time of the Canterbury Tales. The ‘real’ Betelgeuse, right now, is 650 years further along in its story and we won’t know what has happened for another six and a half centuries. Sirius B—A gentler end Sirius B orbits its famous companion, Sirius A—the brightest star in the entire night sky—about once every 50 years. Sirius B is so dim that its existence is something of a ‘just trust us, it’s there’ situation. The Hubble Space Telescope photographed it by deliberately overexposing Sirius A just to reveal the tiny dot of Sirius B beside it. This wasn’t always the case. For roughly a hundred million years, Sirius B was happily burning fuel on the Main Sequence as a hot, blue B-type star, 5 times the mass of our Sun. After exhausting the fuel in its core, it became a red giant, then shed its outer layers as a beautiful expanding shell of glowing gas called a planetary nebula, leaving the hot core behind as a white dwarf. What remains is extraordinary: the mass of a star compressed into a ball roughly the size of the Earth, still glowing at around 25,000 K despite being only 2% as luminous as our Sun. Sirius B now sits in the lower left of the HR Diagram—hot, but very dim— slowly cooling over billions of years. Unlike Betelgeuse, Sirius B’s story ended not with a bang but a quiet sigh. It simply wasn’t massive enough to explode.

Image: Sirius A and B Image Credit: NASA

A tale of three stars The pattern is clear: the more massive the star, the shorter and more dramatic the life. Our Sun will outlast Betelgeuse by a factor of over a thousand.

So what does it all mean? When Hertzsprung and Russell first plotted those dots back in 1910, they had no idea they were drawing a map of stellar life and death. What looked like a simple graph of temperature versus brightness turned out to be one of the most powerful tools in all of astronomy. From it, we can look at any star and ask: Where are you in your life? A hot blue dot in the upper left of the Main Sequence is young and burning furiously. A star drifting to the upper right is ageing, cooling and swelling. A tiny, faint dot in the lower left has reached the end of the road. Our two examples bookend the story nicely. Betelgeuse—massive, dramatic, living fast—blazed through 8 million years on the Main Sequence and is now a swollen red supergiant ticking toward one of the most violent events in the universe. Sirius B— more modest in mass —burned steadily for over 100 million years before quietly shedding its outer layers and retiring as a white dwarf, a glowing cinder that will slowly cool over billions of years. And our own Sun? It sits contentedly in the middle of the Main Sequence, about halfway through a 10-billion-year life, with no plans to cause any drama for a very long time. The HR Diagram started as a curiosity—a pattern nobody expected to find. It became the cornerstone of how we understand stars: where they come from, how they live, and how they die. Not bad for a graph with some funny letters along the bottom. Not so scary after all. Author’s Note: This article is intended for general interest and enjoyment. While every effort has been made to ensure accuracy, it is not a peer-reviewed or academic resource. For an in-depth study, please refer to a recognised astronomy textbook or journal.

Image: Stages of Star Formation Image Credit: NASA

Volunteer Spotlight: The Jazzy Joel Brajkovich By Louise Kaestner Photo credit: Joel Brajkovich and Louise Kaestner Frame Credit: Image by pngtree.com

Tonkin Highway stretches out before me. The Ellenbrook turn off looms. I realise then that I should have been on Roe highway to get to the classy BMT Garden Café to meet up with the jazzy Joel Brajkovich for our bruncheon interview. I reroute, via my mind, and arrive 10 minutes late. Joel is waiting for me in the restaurant. We head out to the manicured garden and sit down next to the table: Mimosa. The fragrant scents of unidentified flora mixed with the nebulous aroma of breakfast cooking lull me under the gentle May sun. It turns out that Joel is as much of a jewel box as the open cluster next to the second brightest star in Cruxis. What inspired you to volunteer at the Perth Observatory? Well, it's kind of funny. My uncle had left us this old Luminar telescope, just a little refracted telescope. He still hasn't asked for it back. I figured one day I'll just play with it, because it was gathering dust in the garage. So, I wheeled it out, and I pointed at the first bright star I saw. It turned out to be Saturn. That's how I saw the rings for the first time. It's just a tiny, tiny little image, but it still blew my mind. Eventually, this is 2021, I think, or 22, we went on a tour at the Observatory and then asked how do I volunteer. They said, oh, there's an intake coming up. I got all excited for that. I can't remember why but I think I forgot the day that the intake was. I didn't realise until the week after. I arranged a meeting with Julie, and I brought a bunch of my old newspaper clippings as well, just to show how much I cared about astronomy, and I was in.

'I've been doing it ever since'. What challenges do you face as a volunteer? I would say a common one I get is when people ask me questions that I don't know the answer to, or about things that aren't exactly my topic. Like, for example, about a month ago, I had someone ask about that asteroid or comet when it was coming past Jupiter. I hadn't been informed about that as of that point. I decided, sometimes you just got to improvise on the spot, and just either try to weave into something that you do know and are familiar with, or if you're absolutely desperate, just make something up. I try to avoid doing that if I can. Although I try to be as factual as possible. What is easy about being a volunteer? There is a good support base. You've got a lot of like-minded people, and if you need info about something, you can always talk to them about anyone else. You get all sorts of support for whatever you need.

Image: Joel Brajkovich using his Dobsonian Credit: Joel Brajkovich

Credit: Joel Brajkovich

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What do you enjoy about being a volunteer? Getting to hang around with people who all like the same thing that you do. You get to enjoy looking at telescopes. You get to do stuff that ordinary people don't normally get to do, or at least not easily.

Do you have any previous volunteer experience? No. This is the first real volunteer experience I've done. I've done like casual work in other fields, but this is the first proper volunteer organization I've done. What are your hobbies? Collecting is the big one. I love all things old and interesting. So it's cameras, books, vacuum tubes. It was military stuff. I recently salvaged an old player piano from going to landfill. My granddad used to own a camera repair shop, so I picked up a lot from him. I've got a bunch of old books and some other nice Kodak pocket cameras that he restored. They're all still working. I've been meaning to use them at some point. I've also got the books that teach me how to fix them. I haven't gone as in-depth with them yet. I know vaguely how to repair the old objects. They are quite tricky, but there are lots of resources online and that that you can find as well. What's your favourite planet, star system, nebula, cluster, galaxy, black hole? I'd say my favourite planet would be Saturn since that's the first one I saw, and it's always a crowd pleaser. No one ever expects to see the rings. And favourite galaxy, or nebula I should say, that's a toss-up between Eta Carina or Orion. They're both nice. And favourite galaxy, probably Centaurus A, because it looks the most interesting to me. Do you have a favourite telescope? My current favourite is my 8-inch Dobsonian telescope. It's collapsible. That's the one you see in the March photo on this year's Perth Observatory calendar. Anything else you want to add? It's fun hobby getting to use telescopes and cameras all the time. It does get expensive, but it can be very rewarding.

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Do you have a quote?

Always keep moving forward. Don't get held up on the past. 57

Western Australia: A Meteorite Impact Structure Wonderland by Siobhán Nims With the return of Mankind to the Moon with the recent Artemis missions, the exciting exploration of our pock-marked lunar neighbour by China’s Chang-e sample return missions and the new analysis of Apollo 17 core samples returned to Earth in the 1970’s but opened for the first time as part of the Apollo Next Generation Sample Analysis (ANGSA) program (Shearer et al, 2024) in recent years, you’d be forgiven for thinking that the Moon is planetary science flavour of the month. Impact craters on the Moon are studied and dated to within a few million years of uncertainty (e.g. Snape, et al 2019) and the promise of evaluating more geologically diverse areas of the Moon, (see, for example, Joy et al 2023), means there has been an increased focus on impact cratering of the Moon. Scientific enquiry aside, any interested observer on a clear night can see the extensive impact cratering on the Moon and the ways it has visibly modified the lunar surface. The Earth, of course, is a much larger body than the Moon. With not only a significantly larger surface area to present as a target for incoming extraterrestrial objects, and a much stronger gravitational pull than the Moon, it stands to reason that over the course of the Earth’s 4.54-billion-year history, it must have been the subject of some pretty impressive meteorite impacts. But where is the evidence of this today? Why don’t we see the very visible and dramatic impact of this on Earth, that we can see on the Moon? Plate tectonics on Earth (which are absent on the Moon), and the consequences of erosion and other phenomena that act on the Earth’s surface and beyond, progressively erase our impact history into the geologic past (Erickson, et al 2020; Huber et al 2023; Hergarten et al 2015). Subduction zones created by plate tectonics can pull meteorite impact craters into the Earth’s mantle, and melt and reform structures. Erosion from wind, moving water or glacial ice wears down the impact structures that might otherwise be left on the surface, and the textbook signs of a meteorite impact—rims and ejecta blankets —are worn away from sight. Likewise, the basins—depressions created by impact structures—present ideal conditions for sedimentation processes to occur, with bodies of water depositing layers of rock and soil, covering over what was once evidence of a meteorite impact. Volcanic activity allows lava to flow into impact basins concealing evidence of shockmetamorphic activity and the earlier topology of the post-meteorite impact area.

Image: Meteorite Impact Crater Moon Credit: Google AI Mode

Image: Stock image of a water droplet and rebound occurring. Large meteorites impacting the ground—on the Moon or Earth—normally result in drastic changes to the body it collides with. Huge circular cratering is a given, but shock waves produce a curtain of ejecta, shaped like an ice cream cone, pushed out of the depression in the ground. With particularly large impactors over a kilometre wide, not only is there a large circular crater left in the ground, but there is also a central uplift in the middle of the depression. That occurs because of elastic rebound from the shocked rocks, just as water droplets rebound on a pond and create a raised central point from which ripples radiate out (Baratoux, D & Reimold W 2016, McSween 2019). Our geological processes on Earth mean that these clues that there has been a giant meteorite impact in the past may not always be easily detected now. Despite these difficulties however, some fascinating research and continued scientific enquiry have led to astonishing discoveries about meteorite impact structures in our own backyard, here in Western Australia.

Yarrabubba Impact Structure The Yarrabubba impact structure lies about 100km south-east of Meekatharra on Yarrabubba Station. The impact structure is an eroded remnant of a former meteorite impact crater. This is located on the Yilgarn Craton. The Yilgarn Craton is one of the most ancient parts of the Earth’s crust. The area was mapped by the Geological Survey of Western Australia (GSWA), and geological samples collected and examined in 1979. Even then, there were features of the samples that geologists concluded were consistent with shock metamorphism (Libby 1979). But what is ‘shock metamorphism’ and what does this have to do with meteorite craters? When meteorites large enough to pass through Earth’s atmosphere without significantly decelerating hit a target rock on Earth, the velocity and mass of the meteorite can result in extraordinarily energetic impacts. For context, when a projectile just a few metres in diameter hits the Earth at high velocity, that object can carry the kinetic energy of an atomic bomb (McSween 2019).

Image: Complex Impact Crater Formation Credit: Eblamble, CC BY-SA 3.0, Wikimedia Commons

These petrologic effects were observed as far back as 1979 in Yarrabubba samples: shock produced forms of quartz and deformation within the minerals were discovered. There is no circular crater left visible at Yarrabubba. But in 2001, aeromagnetic images of the area were processed at Geoscience Australia. They suggested an elliptical aeromagnetic anomaly at the site measuring approximately 20 km north to south, and 11km east to west (MacDonald 2003; Erickson 2020). Although no rim or central uplift were preserved anymore, the magnetic anomaly likely represents the remnant of the deeply buried central uplift of the structure. That, in turn, is consistent with an original crater diameter spanning some 70 km (MacDonald 2003; Erickson 2020). Later in 2002, shatter cones were identified in the area (MacDonald 2003). As the name suggests, shatter cones are cone shaped objects – picture a badminton shuttlecock without the rounded end, and made out of rock. Shatter cones can range in size from millimetres to up to several metres long. Often they will have a conical pattern of lineations or striations—the so called ‘horse tail’ pattern of markings (Baratoux, D & Reimold W 2016). Usually, but not always, the apex of a shatter cone points in the direction of the centre of the impact crater (MacDonald 2003). Shatter cones tend to lie in a distinct pattern of orientation. That’s important, because changes in that pattern can tell us whether something might have interfered either at the time of impact or much later to re-orient the shatter cones (see e.g. Brenner 2025).

Image: Scatter Cones from Neereno Hill, Three Springs, Western Australia Credit: Siobhan Nims

The presence of shatter cones is a very distinctive feature of impact structures (Cavosie, 2026; Baratoux, D & Reimold W 2016). In fact, it is determinative—if you have shatter cones at a site, you have an impact structure caused by a high velocity impact of a bolide such as a large meteorite. So, with the identification of shatter cones at Yarrabubba in 2003, there was confirmation that the site was indeed an ancient impact structure. But the million-dollar question remained—just how ancient an impact structure was Yarrabubba? For many years this remained unknown, and the subject of ongoing debate. The Yarrabubba impact structure was previously estimated to be somewhere between 2640 Ma (2640 million or 2.64 billion years old) and 1200-1075 Ma (1200-1075 million or 1.2-1.075 billion years old) (Erickson 2020). Finally, in 2020, there was a breakthrough. Yarrabubba was established as the oldest recognised meteorite impact structure in the world. An impact age was constrained to 2229±5Ma (between 2224–2234 million or 2.224–2.234 billion years old) using U–Pb testing of shock-recrystallised monazite and neoblastic zircon samples. These samples were specifically taken from impact-generated melt rock, meaning that researchers could have some confidence it likely originated from the large, high speed meteoritic impact whose age they were trying to pin down (Erickson 2020). The samples also came from the same area as the shatter cones that confirmed that an impact had occurred there. The study used a method called U–Pb geochronology by secondary ion mass spectrometry (SIMS) to analyse recrystallised monazite and zircon (Erickson 2020). This method measures the decay of Uranium (U) and Thorium (Th) isotopes into Lead (Pb) and the proportion left of each in a sample. Zircon and monazite are both materials that have some Uranium and Thorium in them. By assessing the ratios of each element left in a sample using the formula below, we can assess the extent to which Uranium/Thorium has radioactively decayed into Lead, and therefore determine how old the sample is (Vermeesch 2022).

Image: Function to determine radioactive decay and age of samples. Credit: P Vermeesch

In this instance, the results showed that material produced in the impact event was about 2229±5Ma (2.229 billion years old). With that finding, Yarrabubba, in Western Australia, established itself as the oldest preserved impact structure in the world.

Image: Meteorite Impact Crater Antarctica at Sunset with Moon on the Horizon Credit: Google AI Mode

Miralga Impact Structure The Miralga Impact Structure can be found in the North Pole Dome on the East Pilbara Terrance (EPT) as part of the Pilbara Craton, about 1500km from Perth, Western Australia (Kirkland et al 2025; Brenner et al 2025). The impact structure has been provisionally named ‘Miralga’. This was the name for a nearby creek and the surrounding area in Nyamal language, the language spoken by the local Indigenous traditional owners (Brenner et al 2025). Two main groups of researchers have focused on dating the Miralga impact structure. Two sets of very different conclusions emerged. Initially, the first researchers contended that the Miralga impact structure was the oldest discovered in the world. They claimed it was created by a high velocity impact some 3.47 billion years ago (Kirkland et al 2025). If that was the case, that would mean it was older than the Yarrabubba impact structure, by over a billion years. This was a bold claim, and one that made the headlines in popular media, social media, podcasts and scientific journals alike, including the prestigious journal Nature. It was claimed that there was ‘unequivocal evidence for a hypervelocity meteorite impact 3.47 billion years ago’ because both spherules and shatter cones were found in the rocks that age. Granted, shatter cones are clear, determinative evidence of a high velocity impact, and likewise, spherules are consistent with that. A spherule is formed when a projectile hits rock at high speed, transferring such vast amounts of energy into the rock, that the rock actually vaporises. As the vaporised rock rises into the air, it begins to cool and then molten droplets of rock condense into spheres, and fall to the ground. So, a spherule also indicates strongly a that a high velocity impact has occurred. The reason why researchers initially thought the impact structure was around 3.47 billion years old was because the spherules and shatter cones were found in rocks containing zircon that age. Moreover, underlying felsic rocks and overlying felsic volcanic rocks in the area were also found to be around 3.47 billion years old. They concluded that if the rocks were about 3.47 billion years old, then surely the meteorite impact that created these spherules and shatter cones must have been too.

Image: Shatter cones from the Pilbara Craton discovered in 2021 (and the subject of research published in March 2025) showing the telltale ‘horse tail’ striations down the conical structure.

Image: Shatter cones examined in 2023 and 2024 by another research team who refute the claim that the Miralga Impact Structure is 3.47 billion years old. The images show how well preserved the shatter cones are. The arrows indicate selected shatter cone apices and point in the direction of shock propagation. Credit: Alec Brenner & Aaron Carvosie

Credit: Kirkland, C.L. et al

However, a separate group of researchers carried out their own investigations into the claims. Following field work in 2023 and 2024, those researchers published their own conclusions a few months in 2025 after the first group had published. They found that the Miralga impact structure could not be anywhere near as old as the previous researchers claimed. But why? First, the Miralga shatter cones were not only found in rocks dated at 3.47 billion years old. More extensive searches found the shatter cone pattern extended to much younger rocks and structures. In fact, the youngest rocks shatter cones were found in were rocks only 2.77 billion years old. Those rocks had to have already existed when the impact event occurred leaving them with the shatter cone striations, forming them into a cone shape – and that was far more recently than 3.47 billion years ago (Brenner et al 2025). The evidence continued to build. A large number of shatter cones were found in strongly chloritised fault zones within metres of faults that cut through basalt in the area. This was an important clue. If the basalts had become chloritised by faulting after shatter cone formation, the action of the faults would likely have destroyed any pre-existing shatter cones. But instead shatter cones overprinted these rocks. What was more, their usual pattern of orientation hadn’t been changed or displaced by the faults. That meant that the shatter cones must have been produced after the fault zones and strong chloritisation came into existance at 2.71Ga (2.71 billion years ago).

Shatter cones were also found in basalt rock created after the eruption of lavas that flowed at 2.77Ga. That provided yet another hint that the shatter cones – and the impact that almost instantaneously created them – must have occurred much later than 3.47 Ga. So, despite all the fanfare of earlier announcement, the Miralga impact structure would appear to not, in fact, be the oldest in the world. For now, that title remains with the Yarrabubba, albeit still within Western Australia. For the time being researchers have constrained the Miralga impact to have occurred from 2.7 to 0.4 billion years ago, well short of the original claim of 3.47 Ga (Brenner et al 2025). What’s next? There are still plenty of questions as to exactly how old the Miralga impact structure is, given how broadly constrained its age remains. Hopefully in the future, radiometric dating using U-Pb analysis, like the type carried out on the Yarrabubba rocks, can be carried out to see what shock-reset minerals such as zircons in the Miralga rocks can reveal. Investigations using paleomagnetism may also yield some interesting results. Paleomagnetism relies on the fact that some magnetic minerals in rocks can ‘lock in’ and record the direction and intensity of a magnetic field when they form. If impactrelated magnetisation is ‘locked in’, that information can be compared to other paleomagnetic results obtained from Pilbara Craton over geologic time, and thereby further narrow down when the possible time of impact was. Further fieldwork will hopefully also yield more impact evidence such as finding impactites—types of rocks created by the immense heat and pressure of a high-speed meteorite impact. Testing any impactites found may also reveal further exciting information about the impact, and when it might have happened. Humans have long watched the skies, fascinated by meteorites and the prospect of what might happen when one collides with the Earth. We look to the Moon, intrigued by the massive meteorite impacts we see the effects of there. And yet beneath our own feet, in our own backyard in Western Australia, we have the oldest evidence of some of the most ancient and interesting meteorite impact events to have occurred on the planet we call home.

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Baratoux, D & Reimold WU (2016), The current state of knowledge about shatter cones: Introduction to the special issue. Meteorit. Planet. Sci. 51, 1389–1434 (2016) doi: 10.1111/maps.12678 Brenner AR et al (2025) Geology and Mars analog potential of the <2.7 billion year old Miralga impact structure, North Pole Dome, Pilbara Craton, Australia, Sci Adv 11, eadu5379 (2025) doi: 10.1126/sciadv.adu5379 Cavosie, A.J et al (2026), Impact-diagnostic criteria for use in confirming a meteorite impact origin of terrestrial geological structures: Recommendations by the Impact Cratering Committee of the Meteoritical Society. Meteorit Planet Sci. https://doi.org/ 10.1111/maps.70163 Erickson, T.M., Kirkland, C.L., Timms, N.E. et al. Precise radiometric age establishes Yarrabubba, Western Australia, as Earth’s oldest recognised meteorite impact structure. Nat Commun 11, 300 (2020). https://doi.org/10.1038/s41467-019-13985-7 Hergarten, S. & Kenkmann, T. The number of impact craters on Earth: any room for further discoveries? Earth Planet. Sci. Lett. 425, 187–192 (2015) Huber, M. S., Kovaleva, E., Rae, A. S. P., Tisato, N., & Gulick, S. P. S. (2023). Can Archean impact structures be discovered? A case study from Earth's largest, most deeply eroded impact structure. Journal of Geophysical Research: Planets, 128, e2022JE007721. https://doi.org/10.1029/2022JE007721 Joy KH et al (2023) Lunar Meteorites. Reviews in Mineralogy and Geochemistry 89: 509-562, doi: 10.2138/rmg.2023.89.12 Kirkland, C.L. et al. A Paleoarchaean impact crater in the Pilbara Craton, Western Australia. Nat Commun 16, 2224 (2025). https://doi.org/10.1038/s41467-025-57558-3 Libby WG (1979), Petrography of 35 rocks from the Sandstone 1:250,000 Sheet, Geological Survey of Western Australia, Petrology Report No. 1007 (unpublished) MacDonald FA et al (2003) Yarrabubba – A Large Deeply Eroded Impact Structure in the Yilgarn Craton, Western Australia. Earth Planet. Sci. Lett. 213, 235–247 (2003) McSween HY et al (2019) Planetary Geoscience Cambridge University Press, 194, 197, 200. ISBN: 9781316535769 DOI: 10.1017/9781316536769 Shearer CK et al (2024) Apollo Next Generation Sample Analysis (ANGSA): an Apollo Participating Scientist Program to Prepare the Lunar Sample Community for Artemis. Space Science Reviews 220: 62, doi:10.1007/211214-024-01094-x Vermeesch P (2022) An Algorithm for U-Pb Geochronology by Secondary Mass Ion Spectrometry. Geochronology, 4, 561–576, 2022 https://doi.org/10.5194/gchron-4-5612022

Image: Aurora Australis Credit: NASA/Jessica Meir

Project Hail Mary

Image: Ryan Gosling in Project Hail Mary (2026) Credit: IMBd Fair Use

Movie Review by Julie Mathews A few years ago, I reviewed the book Project Hail Mary for this newsletter, so I was more than excited to see what the movie adaptation would be like. My enthusiasm increased even further when I heard that Ryan Gosling was going to play the lead role. With high expectations, I booked hubby and myself into the fancy lounge at Hoyts Midland, where food is delivered straight to your seat and you can relax in luxurious recliners while enjoying the movie. From the opening scenes, I was hooked. Ryan wakes up with amnesia aboard a spaceship hurtling through space—completely alone, apart from two corpses. I was glued to the screen as the mystery slowly unfolded. Gosling is outstanding as Ryland Grace, the rumpled, slightly bewildered high school teacher who just so happens to have a background in molecular biology. His scientific knowledge is crucial to saving Earth from a catastrophic freeze, yet there is one puzzling question: he was never meant to be on the mission. So why is he there? As his memories gradually return, the pieces of the story fall into place, revealing both the enormous stakes and the personal sacrifices involved. Once again, author Andy Weir demonstrates his remarkable talent for creating compelling stories that blend science, survival, humour and humanity. Directed and produced by Phil Lord and Christopher Miller, the film benefits from a team that clearly understood both the heart and the scale of Weir's novel. Ryan Gosling also served as a producer, alongside Amy Pascal, Aditya Sood, Rachel O'Connor and Andy Weir himself. Their combined efforts have resulted in a film that remains faithful to the spirit of the book while creating a cinematic experience all its own. The filmography is superb, creating a space environment that feels both believable and breathtaking. The visual effects are stunning without overwhelming the story. The sense of isolation and wonder is beautifully captured throughout. One of the things that impressed me most was learning why Gosling wanted to make the film. In an interview, he explained that he was drawn to Project Hail Mary because he wanted to create an epic, hopeful movie that he would be proud for his own children to grow up with. That sense of optimism shines through the entire film and sets it apart from many darker science-fiction stories. At its heart, however, Project Hail Mary is more than a science-fiction adventure. It is a story about friendship, courage and self-discovery, with a poignant and deeply satisfying ending that left me both smiling and emotional—even hubby was raving about it. Whether you've read the book or are coming to the story for the first time, Project Hail Mary is a thoroughly entertaining and surprisingly heartfelt film. For me, it lived up to the excitement I felt when I first heard it was being made—and that's no small achievement.

Julie's Rating: 69

Image: Screenshot Credit: Louise Kaestner

Book and Movie Review by Paul Fisher Warning: Spoilers ahead! ‘What is your name?’ An astronaut wakes on a space ship, after an indeterminate time in a coma. He has no memory—doesn’t even remember his own name—doesn’t know where he is or what he’s meant to be doing. But gradually his memory returns. And his mission—to save the Earth! Project Hail Mary is the third space novel by Andy Weir, following The Martian and Artemis, and the second (after The Martian) to become a hit movie. And like The Martian, it is very much a one-hander, told in the first person by the main protagonist. In the movie, Ryan Gosling plays Ryland Grace, the reluctant saviour. The movie closely follows the structure of the book, with Grace gradually regaining his memories, telling the full back story through a series of flashbacks. Grace is a high school science teacher, but in a former life he was a brilliant scientist who got forced out of academia because of a radical paper claiming that life could exist in the absence of water. Because of this background, Grace is approached by Eva Stratt, a hard-bitten European technocrat who has been nominated to run a project to counteract an existential threat to the Earth and its inhabitants. In the book, Stratt is abrupt, hard-edged and arrogant, with seemingly unlimited powers to command whatever resources she needs for the task. The movie version is a lot more relatable, but still ruthless when necessary. Stratt sees in Grace the skills and mind-set ideally suited to investigate and solve the mystery: something is removing energy from the Sun, reducing its luminosity by a measurable amount. Unless something is done, the Earth will enter a new ice age, with catastrophic effects on our civilisation. Grace discovers that the problem is caused by microorganisms (astrophage) which thrive at ultra-high temperatures. They store incredible amounts of energy, which not only allows them to attack the Sun, but allows them to be an amazing rocket fuel. Astronomers have noticed similar dimming of all nearby stars with one exception—Tau Ceti—so an expedition is mounted to Tau Ceti to investigate and hopefully solve the mystery of why this star is immune to the problem. The ship (the Hail Mary) is powered by astrophage and has a crew of three specialists. But before launch, a key crewman is killed in an accident, leaving a vacancy that can only be filled by Grace. Despite his opposition, Grace is drugged and dragged onto the ship, where he and two companions are placed into induced comas for the long trip to Tau Ceti. Only Grace survives the journey.

Book Rating: 70

Shortly after arrival at Tau Ceti, Grace is joined by an alien space ship. After much trial and error, he achieves communication with the alien—a five-legged creature apparently made of stone, with no face. Grace names his new friend Rocky. Rocky comes from a planet orbiting Epsilon Eridani—which is shortened to Erid in the story. The movie heavily promotes the comedic and cutsie aspects of Rocky, while the book plays up his intelligence and engineering skills. Together, Rocky and Grace study the astrophage at Tau Ceti, finding it migrates between the star and an inner planet with a carbon dioxide atmosphere strikingly similar to that of Venus. In one of the few action sequences of the movie (and also the most spectacularly beautiful), Grace obtains a sample of the atmosphere. In doing so, he is seriously injured but rescued by Rocky, who is himself seriously damaged. After their recovery, the pair isolate a microbe that feeds on astrophage—they call it Taumoeba. The Taumeba in the planet’s atmosphere eats astrophage, thus keeping it from destroying the star. If they can return samples of Taumeba to Earth and Erid, it may be possible to save both planets. Grace and Rocky start off for their respective home planets, but more twists and turns await before the story comes to an end. Project Hail Mary is the story of an everyman, who—against his will—finds himself on a mission to save his planet. He meets a fellow traveller whose own planet is suffering the ravages of astrophage. An unlikely friendship ensues, with a surprising ending. Various commentators have considered whether one should read the book before seeing the movie, or vice versa. I read the book first (twice) and I’m glad I did. The book is quite long and includes a lot of in-depth discussion of the science and logistics of the quest—much of which is glossed over in the movie. I think reading the book first allows one to better understand the movie, without detracting from it in any way. The movie is 2½ hours long and still misses most of the science that the book contains. There is supposedly a four-hour director’s cut coming, which would definitely be worth seeing. I rate the book very highly. I like Weir’s style which combines humour with hard science. On the other hand, the movie probably has a broader audience reach. The characterisation of Grace by Ryan Gosling is sometimes a bit slapstick but otherwise is a very solid effort, with his interactions with Rocky particularly well done. The cinematography by Australian Greig Fraser is masterful and very likely to be nominated for an Oscar.

Movie Rating: 71

Sunday Guided Day Tours

Discover the secrets of the universe and the rich history of Perth Observatory on our Sunday guided day tours! Nestled in the stunning bush settings of Bickley, our Observatory is the perfect place to explore the wonders of the cosmos. Our knowledgeable guides will take you on a journey through time, from the Observatory’s humble beginnings in 1896 to its move to Bickley in 1966 and beyond. You’ll get to tour the Meridian, Astrograph & Calver Telescopes, learn about timekeeping and explore the museum to discover fascinating stories about the Observatory’s past and present. If the weather permits, you’ll have the opportunity to safely observe the Sun and its sunspots. It’s an experience you won’t want to miss! There is no need to book, simply come up between 1 and 4 pm and pay in our shop. Our Sunday day tours are the perfect way to spend a relaxing afternoon with family and friends, surrounded by the beauty of nature and the mysteries of the universe.

Perth Observatory Night Cameras

Perth Observatory is a member of the Global Meteor Network, and we now have seven cameras recording the night sky. These state-of-the-art cameras capture meteors, satellite passes and other celestial events, providing us with a unique view of the Solar System’s formation and evolution. The footage captured by these cameras is not only valuable for scientific research but also for public viewing. You can watch live images from the cameras at night, which update every three minutes during the night. Additionally, we’ve made available condensed footage from the previous night, highlighting every meteor detection. Be warned, it’s hard not to get hooked on watching these videos.

Image: VLTI reconstructed view of the surface of Antares Image Credit: ESO

Antares

What’s In July’s Skies

by Louise Kaestner; Co-author Google AI Mode The Rose Cluster—M5, NGC5904: Sitting high in the constellation of Serpens, this cosmic snowball is a breathtaking spectacle that looks like a burst of celestial glitter frozen in time. Discovered by Gottfried Kirch in 1702, The Rose Cluster (M5) is one of the oldest and largest globular clusters in our Milky Way galaxy, packing over 100,000 stars into a sphere roughly 165 light-years across. Unlike its younger, rebellious open-cluster cousins who tend to drift apart after high school, the stars in M5 are tightly bound by an intense gravitational hug, staying together like a fiercely loyal, ancient family. Gazing at it through a telescope at the Perth Observatory, the dense, blazing core unfurls into delicate, glittering chains of stars that look exactly like the petals of a shimmering cosmic rose blooming against the velvet dark of space. When you look at M5, you are quite literally looking back in time to the dawn of the universe itself. At an estimated age of nearly 13 billion years, these stars are galactic senior citizens, born long before our own Sun was even a thought in a nebula's mind. Because it is so old, most of its massive, short-lived stars are long gone, leaving behind a beautiful retirement village of low-mass yellow and red giants, alongside a fascinating population of "Blue Stragglers"—stellar vampires that have merged or stolen material from their neighbours to cheat death and look deceptively young again. It sits about 24,500 light-years away from Earth, but it shines so brightly that on a crisp, perfectly dark night away from the city lights, you can just catch a glimpse of this ancient stellar city with the naked eye, a humbling reminder of the universe’s enduring majesty.

Antares—Alpha Scorpii: Anchored deep in the chest of the celestial scorpion is Antares. This fiery red supergiant is a real showstopper in our winter night skies. Its name literally means ‘Anti-Ares’ or the ‘Rival of Mars’, and it isn’t hard to see why; its brilliant, pulsing orangered hue has been confusing skywatchers for millennia, giving the God of War a serious run for his money. Antares is an absolute monster of a star—if you swapped it with our Sun, it would swallow Mercury, Venus, Earth, and stretch all the way out past Mars. It’s also living on the edge. As a cosmic heavy-hitter nearing the end of its life, it’s constantly puffing out its outer layers into a beautiful, dusty reflection nebula, blowing off steam before it inevitably goes out in a spectacular supernova explosion that will briefly give Earth a second moon. It’s a beautifully dramatic cosmic beacon, and looking at it through the telescope is like staring straight into the beating, glowing heart of the universe itself.

What’s In August’s Skies

by Louise Kaestner; Co-author Google AI Mode The Lagoon Nebula—M8, NGC6523: Floating majestically within the star-studded bands of the Milky Way core in Sagittarius, this cosmic masterpiece is a bustling stellar nursery that truly lives up to its serene name. Discovered by Giovanni Hodierna before 1654, the Lagoon Nebula is a colossal cloud of interstellar gas and dust spanning a massive 110 light-years across. When you peer at it through a telescope at the Perth Observatory, a striking, dark lane of dust cuts right through the glowing heart of the nebula, mimicking a tranquil channel of water winding through a glowing celestial island. This lagoon is anything but quiet, though; it is a violent cauldron of creation fueled by intense ultraviolet radiation from hot, young stars—including the blistering powerhouse Herschel 36. This radiation sculpts the surrounding hydrogen gas into turbulent, twisting dust pillars and cosmic waves, making it one of only two star-forming nebulae faintly visible to the naked eye from mid-southern latitudes, a breathtaking portrait of cosmic birth painted across the velvet dark.

The Wild Duck Cluster—M11, NGC6705: Perched elegantly within the shield of the Scutum constellation, this spectacular open cluster is one of the most densely packed star cities in our galaxy. Discovered by Gottfried Kirch in 1681, the Wild Duck Cluster earned its delightful nickname from Admiral William Henry Smyth, who noticed that through a smaller telescope, its brightest, burning stars form a distinct, V-shaped wedge that looks exactly like a flock of wild ducks flying in formation. Unlike its loose, laid-back open-cluster cousins, M11 jams around 2,900 hot, young stars into a tightly compressed cosmic neighborhood, making it look almost like a globular cluster trying to pass as an open one. Gazing upon it through a telescope is a dazzling experience; it is a compact, glittering vault of blue and yellow diamonds scattered across the velvet dark, a celestial flock frozen midflight on an eternal journey through the cosmos.

NGC6523 Lagoon Nebula

Image: Lagoon Nebula Image Credit: Wikimedia Commons

M55 Sagittarius Globular Cluster

Image: Sagittarius Globular Cluster

Image Credit: ESO/J. Emerson/VISTA

What’s In September’s Skies by Louise Kaestner; Co-author Google AI Mode Ring Nebula—M57, NGC6720: Suspended gracefully within the summer constellation of Lyra, is the Ring Nebula. This ethereal cosmic donut is the universe’s ultimate wedding band—though it’s a bit of a tragic romance. Discovered by Antoine Darquier de Pellepoix in 1779, this planetary nebula is actually a giant, glowing shroud of gas cast off by a dying star that ran out of fuel roughly 4,000 years ago. At the very altar of this ring sits a tiny, blisteringly hot white dwarf star, the exposed corpse of the original star, acting like a cosmic diamond under a spotlight. It screams out ultraviolet light that makes the surrounding gas shells glow in brilliant concentric rings, looking exactly like a spectral diamond engagement ring dropped on the velvet black floor of the celestial reception. Peering at it through a decent size telescope, you'll remember that even stars like to put a ring on it when their time is up.

Sagittarius Globular Cluster—M55, NGC6809: The Sagittarius Globular Cluster pours beautifully into the eastern side of the Sagittarius constellation. It is the bright celebratory explosion of starlight cosmic reception party that you never want to leave. Finding it is a delightful game of celestial connect-the-dots with everyone’s favourite asterism, the Teapot. If you imagine the Teapot brewing a fresh batch of cosmic tea, look over at its handle on the left side. Grab the two stars that make up the outer edge of the handle (Ascella and Kaus Media) and extend a line curving eastward and slightly south for about 17 degrees—right out past where the steam is rising—and you will land smack-bang on this shimmering open-air ballroom of stars. Unlike its uptight, densely packed globular cousins who crowd the dance floor like eager youth, M55 is famously one of the loosest, most relaxed clusters in the sky. Spanning about 100 light-years across, its 100,000 ancient stars are spaced out beautifully, giving everyone plenty of elbow room to socialize. When you gaze at it through a telescope, it doesn't look like a blurry smudge; instead, it resolves into a gorgeous, grainy scatter of glittering diamonds that looks exactly like a handful of silver confetti thrown high into the air to celebrate a happily-ever-after against the velvet dark.

Other images credit: ChatGPT, Copilot, Perplexity.ai, Google AI Mode

Amateur Astronomer Cheat Sheet The Rose Cluster

The Wild Duck Cluster

M5, NGC5904

M11, NGC6705

Constellation: Serpens

Constellation: Scutum

Object type: Globular Cluster

Object type: Open Cluster

Right Ascension: 15.18 hours

Right Ascension: 18.51 hours

Declination: 02.04 North

Declination: 06.16 South

Distance: 24,500 light years

Distance: 6200 light years

Magnitude: +6.7

Magnitude: +6.3

Width: 165 light years

Width: 25 light years

Age: 13 billion years

Age: 220 million years

Stars: 500,000

Antares Alpha Scorpii

Lagoon Nebula M8, NGC6523 Constellation: Sagittarius Object type: Nebula Right Ascension: 18.04 hours Declination: 24.23 South Distance: 4100 light years Magnitude: +6 Width: 110 x 50 light years

Constellation: Scorpius Object type: Binary star Right Ascenion: 16.29 hours Declination: 26.26 South Distance: 550 light years Magnitude: +1.1 Absolute Magnitude: -5.28 Mass: 12 solar masses Width: 1 billion kilometres

Download printable PDF Cheet Sheat

Cosmic Cursors Images are screenshots by Louise Kaestner

We spend so much time glued to our technology these days—I know I definitely do! Somewhere between the end of 2025 and the start of 2026, I stumbled upon this brilliant site packed with all kinds of cursors— yes, even planetary ones. Hidden away in my Windows Solid State Drive (C: > Users > lcmckwd > Pictures > Mouse Pointers), I now have a little galaxy of unusual cursors I’m still getting used to—and absolutely love. If you want to give your mouse pointer a bit of space flair, check out RealWorld Designer. Download the set you like and save it somewhere you can find easily. Then, hop into your computer settings: in Windows, go to Accessibility > Mouse Pointer and Touch, and choose 'Customise Pointer Image.' Browse to where you saved your new cursors and pick your favorites. Once that’s done—Venus is your aunty! Enjoy your new cosmic cursor adventure.

A Quick Look In The Astroshop!

Image: Hand painted watercolour night sky background

Image Credit: kjpargeter on Freepik

SUPPORT PERTH OBSERVATORY

CONTAINERS FOR CHANGE Help Perth Observatory through the Containers for Change scheme. Please take glass, plastic, aluminium, steel and paper-based cartons between 150ml and 3L to your local refund depot and use the Perth Observatory (Scheme ID: C10424615). The Perth Observatory Volunteer Group will receive 10 cents for each container. Save the ID on your phone for every time you recycle your containers. Find your local refund depot and get more info on what containers are eligible for refunds. here:

containersforchange.com.au/wa Can’t get to a refund centre? We have a dedicated and labelled bin on-site for you to add your clean container donations when you next visit the observatory. Our maintenance volunteers collect donated containers and take them to the refund centre. Thank you for helping the POVG promote sustainable and environmentally conscious practices and diversifying ways for us to raise much-needed funds. Your help supports the continuing upkeep and running of Western Australia’s oldest observatory!

The Funny Side

Memes by Imgflp and Google AI Mode

Image: The Little Gem Nebula Image Credit: NASA

Contact Us Perth Observatory 337 Walnut Road 6076 Bickley, WA (08) 9293 8255 newsletter@povg.org.au perthobservatory.com.au