COACHELLA VALLEY INDEPENDENT // 13
AUGUST 2021
NEWS
CVINDEPENDENT.COM/NEWS
AUGUST ASTRONOMY V
The moon makes way for what could be a brilliant Perseid meteor shower
By Robert Victor
enus, Saturn and Jupiter are all easy to see in August’s early evenings. Jupiter and Saturn, up in nearly all of August’s dark hours, reach their closest and brightest points of the year. The best chance to see a fourth planet—Mercury—comes late in the month; faint Mars is unlikely to be seen through haze and bright twilight glow. If you enjoy a very thin crescent moon, watch at dawn on Aug. 7 and dusk on Aug. 9. The diminished moon should make for a great Perseid meteor shower this year, peaking on night of Aug. 11-12. Finally, the blue moon on the night of Aug. 21-22 may attract little media attention—because of a mistake in a respected astronomy magazine many years ago. In the evening sky: Three planets are well seen in all of August: Brilliant Venus, of magnitude -4, low in the west at dusk; Jupiter, of magnitude at dusk, with Spica 33 degrees to its lower -2.9, rising in the east-southeast; and Saturn, of left. Look for the Summer Triangle of Vega, magnitude +0.2, some 19 degrees to the upper Altair and Deneb high in the eastern sky at right of Jupiter. dusk. In mid-August, a line from Vega to Altair, Finding Mars is a challenge! At magnitude 34 degrees long, extended 31 degrees, locates +1.8, it’s as faint as it ever gets, and is mired very Saturn. Antares, red supergiant heart of the low in bright twilight. You’ll need binoculars, Scorpion, is in the south to south-southwest at very clear skies and an unobstructed view. Try dusk. The Milky Way is spectacular in August at for the red planet 11 degrees to the lower right nightfall when a bright moon is absent. of Venus on Aug. 1. On Aug. 9, look low, 17 Follow the moon at dusk as it waxes from a degrees to the lower right of Venus, for a thin thin crescent to full, Aug. 9-22. On Aug. 10, the crescent moon, 37.5 hours after new. Binoculars 8 percent crescent is 5 degrees to the right of may show Mars 3 degrees to the lower left of the Venus; on Aug. 11, the 14 percent crescent is 9 3 percent lunar crescent. That evening, Mars will degrees to Venus’ upper left. set less than an hour after sunset, and Jupiter As mentioned above, this should be an will rise less than a half-hour before Mars sets. excellent year for the annual Perseid meteor Mars and Jupiter are just 2 to 3 degrees above shower. On the evening of Wednesday, Aug. 11, opposite horizons 44 minutes after sunset the 15 percent crescent moon sets just 3/4 of on Aug. 9, so a sighting of all four planets an hour after twilight ends, leaving the sky dark simultaneously requires good low views toward and moonless. The greatest number of “shooting the east-southeast and 10 degrees north of west. stars” will occur during predawn darkness on Mercury (magnitude -0.5) emerges, passing Thursday, Aug. 12, until twilight begins, about only four arcminutes (1/15 of a degree) to the 90 minutes before sunrise. Meteors can be seen lower left of Mars on Aug. 18. A telescope will anywhere in the sky; what the shower meteors be required to split the tight, unequal pair. If have in common is their paths: All originate you succeed in spotting the pair, then you can from a common radiant, in the constellation see five planets simultaneously! After Aug. 18, Perseus in the northeast. Mercury climbs 2 degrees higher in twilight by At dusk on Aug. 12 and 13, the moon is 8 the month’s end, and is easier to find, though degrees from Spica. On Aug. 16, the two-thirds faded to magnitude -0.1. Find Mercury 20 to 16 gibbous moon is 5 degrees to the upper left of degrees to the lower right of Venus Aug. 19-31, Antares. On Aug. 20 at dusk, the 98 percent as both planets shift south of west. moon is 5 degrees below Saturn. On Aug. 21, Telescopic views: Watch Saturn’s rings for the moon at dusk is 5 degrees to the lower right several nights before and after its opposition of Jupiter. The full moon occurs the same night, on Aug. 1. The rings are currently tipped at 5:02 a.m. on Sunday, Aug. 22. It’s also called 18 degrees from edgewise, and extend 42 a blue moon—the third full moon of a season arcseconds in width. Follow Titan, Saturn’s with four full moons. What, you thought a blue largest moon, in its 16-day orbit around the moon meant the second full moon of a calendar planet. Jupiter, at opposition on Aug. 19, month? Not so! displays parallel belts of clouds on a disk 49 The moon passes just 4 degrees south of arcseconds wide. Venus this month shows a Jupiter about 3 a.m. on Aug. 22. Note Jupiter tiny gibbous disk, 82 to 73 percent illuminated, is still within 5 degrees of the “blue moon” as and 13 to 15 arcseconds across. dawn begins to brighten on Sunday. Other evening sights: Golden Arcturus At dusk on Aug. 22, the 99 percent moon begins the month high in the west-southwest rises within 13 degrees to Jupiter’s lower left.
August's evening sky chart. ROBERT D. MILLER
All the lunar and planetary groupings mentioned here are illustrated on the Sky Calendar. To subscribe for $12 per year, or to view a sample issue, visit www. abramsplanetarium.org/skycalendar. Morning planets: Jupiter, with Saturn to its lower right, is low in the southwest at dawn at the start of the month. The two giant planets drop lower each morning. Saturn is at opposition on the night of Aug. 1-2. Jupiter is at opposition on Aug. 19, as Earth passes between the sun and these planets. Bright stars in morning: They are plentiful— the same stars which adorn the evening sky in January. The last to rise is Sirius, the Dog Star. Follow Orion’s belt down to the east-southeast horizon to catch Sirius rising in the morning twilight glow in August’s second week. Over many years, I have often ended my Perseid meteor vigil waiting for Sirius to appear before
calling it a night. The moon wanes to a thin crescent through Aug. 7, and Aug. 22-Sept. 5. Watch the waning moon pass through Taurus (Pleiades, Aldebaran and horns) as a crescent Aug. 2-4 and again near last quarter phase, Aug. 29-31. Catch a beautiful crescent moon with earthshine among the stars of Gemini on Aug. 5 and 6 (near Pollux and Castor). On Aug. 7, catch the thin, 1 percent old crescent moon, 25.5 hours before new, rising 10 degrees below Pollux. Catch the waxing gibbous moon near Saturn most of the night of Aug. 20-21. Catch the full “blue” moon near Jupiter throughout the night of Aug. 21-22. Robert Victor was a staff astronomer at Abrams Planetarium at Michigan State University. When the coast is clear, he looks forward to sky-watching sessions, hopefully in time for the fine display of three planets in the evening sky in autumn 2021. CVIndependent.com