Measuring the Solar System: A Collaborative Global Student Program Mike Simmons1, Arvind Paranjpye2, Rosa Doran3,4,5, Manoj Pai (1) Astronomers Without Borders, California, USA, (2) Inter-University Centre for Astronomy and Astrophysics, Pune, India, (3) Galileo Teacher Training Program, Lisbon, Portugal, (4) Núcleo Interactivo de Astronomia, Lisbon, Portugal, (5) Global Hands-On Universe, California, USA
SUMMARY The transit of Venus on 5 June, 2012 provides the opportunity to replicate an entire chain of solar system measurements from the ancient Greeks’ determination of the Earth’s diameter to the SunEarth distance in kilometers. A yearlong program of simple hands-on classroom projects, culminating with Venus transit, will be organized, disseminated and managed by Astronomers Without Borders.
INTRODUCTION Measurements of the dimensions of the Earth and inner solar system began in Greece 2300 years ago when Eratosthenes noted the Sun’s shadow at different latitudes, from which he determined the Earth’s diameter. By the 17th century the invention of the telescope permitted measurements to be made during planetary transits of the Sun, giving a relative scale to the inner solar system. Transits of Venus, occurring only six times in the 400 years since the telescope’s invention, allowed for the scale of the solar system to be measured in terrestrial units, prompting observing expeditions to sites around the world during the 18th and 19th century events in order to obtain the most precise results possible. These historic observations are recreated in some classrooms. The transit of Venus on 5 June, 2012 – the last such event until the 22nd century – provides the opportunity to replicate this entire chain of measurements. New technologies available for the first time during this rare event provide an unparalleled opportunity for worldwide education. Students in different locations can collaborate to obtain the multiple, widely-separated observations needed for many of these measurements without the travel required earlier. Real-time communication between classrooms provides a unique opportunity for first-hand experience of the Earth’s shape and size through shared observations. Attention from science organizations and media assure that the Venus transit will be a high-profile event.
1. Measuring the size of Earth and one’s location on it • Measure the radius of the Earth by observing the minimum gnomon shadow on the same day at various latitudes. • Classes at the same longitude work together on the same day, sharing observations in real time. • Observation of the disappearance of a gnomon’s shadow on “zero shadow day” (tropical locations only). • Measurement of the minimum length of a gnomon’s shadow on the dates of the solstices and equinoxes to determine locaion. • Cardinal points of the compass. Students in Poland taking part in the Eratosthenes Project of Ellinogermaniki Agogi. Calculating the difference in latitude based on shadow observations.
4. The Venus transit: Measuring the absolute size of the solar system • Two steps 1. Measure the Earth-Sun distance relative to Earth’s diameter by making observations from two or more locations 2. Calculate the actual distances between the Earth, Venus and the Sun in kilometers. • Two methods 1. Time the contacts of the Venus transit from different locations on Earth 2. Measuring the angular velocity of Venus during transit (Halley's method). • Classes at different locations work together, combining their measurements to obtain the results. • A phone app and website applet for use in making timing measurements and sending them to a central site is being developed (see below).
2. Measuring the relative scale of the solar system • Measurement of the ratio of the orbital radii of Earth and Venus. • Method 1, measure the maximum angular separation of Venus and the Sun. • Method 2, measure the parallax of Venus as observed from different locations on Earth. • Simplest with schools on the same latitude or longitude but more advanced classes can adjust for differences on both coordinates. • Classes at different locations work together, combining their measurements to obtain the results.
The Venus Transit Phone App Developed by Steven Van Roode This app will be used by classrooms as well as amateur astronomers and others worldwide contributing to a global project.
Venus before and after greatest elongation when the relative scale of the solar system can be measured. © Tunc Tezel / TWAN
PROGRAM DESCRIPTION A yearlong program of classroom projects, culminating with the Venus transit, will be organized, disseminated and managed by Astronomers Without Borders. Classrooms worldwide will be engaged in these measurements and encouraged to collaborate with other classrooms in distant locations. The program consists of a series of simple, hands-on projects making measurements of the size of the Earth and inner solar system using instrumentation created with common, easily obtained materials augmented by instructional materials disseminated by Astronomers Without Borders and others. This program will be the first to bring together all of these projects under a single program open and readily available to classrooms anywhere in the world where an Internet connection is available. The program will continue with all the experiments except the Venus transit observation, with the network and infrastructure created in the run-up to the transit remaining in place to serve an ever-increasing number of schools as the Internet reaches more sites. The program will also be expanded to create international observing programs in education at all levels, and including amateur astronomers, as Astronomers Without Borders has been doing. These observational programs will include not only the objects and phenomena that are always available (stars, planetary motion, solar motion, etc.) but also transient events such as lunar occultations, variable stars, meteor showers, comets, near-Earth asteroids, solar phenomena and other transient events.
3. Measuring the relative size of the Sun and observing its phenomena • Angular diameter of the Sun measured directly. • Solar phenomena observed including sunspots, solar rotation, limb darkening. • Prominences and flares observed in H-alpha light, where possible. • Solar constant measured directly. • Simple spectrographs made in the classroom from paper and a CD to observe the solar spectrum. Schoolgirls observing the Sun in H-alpha light in Iraq (R) and directly with solar filters in Afghanistan (L).
Additional projects based on multiple observations by collaborating classrooms will be added beginning with the 2012-13 school year.
REAL-TIME, INTERACTIVE GIS DATA SYSTEM ESRI Geographic Information Systems (GIS) online tools will be used to manage, display and analyze data. These new interactive web-based tools will provide real-time access to all participating classrooms.
OUTCOME The Venus transit and the expanding use of online communications technologies combine to provide a unique opportunity to engage classrooms around the world without regard to location or cultural differences. Students will gain not only scientific knowledge and an understanding of simple scientific methodology through inquiry-based learning, but also knowledge of the wider world, and the Universe, in which they live.
Example of GIS map of communities including data on each, interactive (clickable) and updated in real time on the website as data is added and modified by the users. A map of classrooms will be similar.
FURTHER INFORMATION This program is a global, collaborative project open to institutions worldwide. Significant exposure for appropriate institutional and corporate sponsors is available. For information on participation contact AWB President Mike Simmons. Mike Simmons email@example.com (or firstname.lastname@example.org ) Astronomers Without Borders www.astronomerswithoutborders.org
PARTICIPANTS Galileo Teacher Training Program Rosa Doran Portugal
Sofoklis Sotiriou Ellinogermaniki Agogi Research and Development Department Greece
Global Hands-On Universe USA
The Inter-University Centre for Astronomy and Astrophysics India
Michael Zeiler ESRI USA Steven van Roode www.transitofvenus.nl