Here’s Heads UP! for August, from my Almanac column in the Westchester Astronomers newsletter. The newsletter is on http://www.westchesterastronomers.org/ – check out the great articles and photos there.
The story goes that August has 31 days because Caesar Augustus stole a few days from February so that his month would have as many days as his next-door-month neighbor, Julius Caesar. It’s just a story, but no matter whose fault it is, the 31 days in August lets us have two full moons – on the 1st and 31st.
There’s lots of planetary activity in the dawn and the dusk skies. Let’s start with our Prime Time skies, where Mars, Spica and Saturn make a striking group low in the west after dark, competing with the Olympics during the Neilson ratings’ summer sweeps month. On the 13th and 14th, Mars slips between Saturn and Spica, forming a mis-ordered stop light, with yellowish Saturn on top, reddish Mars in the middle and bluish Spica standing in for green on the bottom. Get your camera – even if you don’t get the focus just right – sometimes the colors come out stronger with an out-of-focus time exposure. On the 21st, the Moon joins the scene, completing a keystone formation. While you don’t need optical aid to enjoy this view, binoculars can enhance the color differences and gathering up so many bright objects into one binocular view is exhilarating.
As Saturn gets lower in our evening sky, we’ll see fewer details in the rings and fewer of its moons as we look sideways through our thick atmosphere, but it’s still a crowd-pleaser. We tried 200x on Mars at the Starway in July – just a fuzzy dot, so not much to see there.
Sagittarius’ classic teapot shape low in the south after dark is at its highest at this time of year. Follow the ‘steam’ from the teapot spout with binoculars or a wide-field telescope to some neat star clusters. A star map makes the trip even more enjoyable. The gibbous Moon overwhelms the view of our fainter friends during the last week of the month.
Meanwhile, in the morning sky, Mercury makes a move to copy Venus’ race into the morning sky. Mercury’s move is just like Venus’, except Venus is brighter (magnitude minus 4 1/2 vs zero), higher in the sky (at 40 degrees vs 16) and larger in a telescope (at 24 arc seconds vs 7.4). But mid-month is a great time to find Mercury. Both Venus and Mercury come to their greatest distance from the Sun in our sky at mid-month at 46 degrees and 19 degrees away from the Sun. It’s a great time to see the members of our inner solar system – a rare event for many people.
In the early morning sky, your telescope will show that Jupiter’s belts have made some changes since it was part of the super show in the evening sky, which rewards the 4am observer.
Telescopic targets, asteroids Vesta and Ceres play near the horns of the bull Taurus, near Jupiter and Venus. Vesta is easier to find at magnitude 8.2 and passing within a half degree of Aldebaran on the 5th and 6th. They’ll come into the evening sky in December. The Dawn spacecraft is completing its examination of Vesta and will leave for Ceres on September 8th. (JPL invites you to host your own “Hasta la Vesta” celebration that day.)
Venus’ distance from the Sun in the sky is good for those who want to see the crescent Moon pass in front of Venus on the afternoon of Monday the 13th. The occultation occurs just about 4:37pm, just before moonset here in the northeast United States and higher in the sky further west of us. When Venus goes behind the Moon, they will be only 4 degrees above the WNW horizon. It may be easier and still very cool to find the Moon and Venus close together when they reach their highest point in the southern sky between 9 and 10am. Which of them will be easier to see? Compare the intense brightness of the tiny, highly reflective Venus and the closer, larger, less reflective lunar crescent.
Everyone’s second favorite summer shower (after showering off beach sand and salt) is the Perseids meteors. They are best in the post-1am darkness on the 12th, when 60 or so bright ‘falling stars’ can streak across the sky. But you can watch a satisfying show any time after 10 or 11pm. If you can’t make the morning shift, you can catch several bright meteors per hour in the evening skies on the 11th or 12th. The fewer evening meteors is similar to how fewer raindrops hit the back window of a moving car. The morning side of the Earth faces the direction the Earth is moving and sweeps up more meteors.
The as-big-as-a-family-car Curiosity rover gets dropped off in Gale Crater on Mars just after midnight on the 5th/6th. Everything – aerobraking, parachutes, rockets, and then a long cable to winch the rover down to the surface – has to work during what JPL is calling “7 minutes of terror” – for its one chance to land on the rusty planet.