This is Dudley Observatory’s Skywatch Line for Friday, September 18, through Sunday, September 20, written by Alan French.
The Moon will reach first quarter very early Monday morning, so a waxing crescent will dominate the early evening skies this weekend. The Moon sets at 9:57 pm Friday, 10:38 pm Saturday, and 11:25 pm on Sunday.
Weather permitting; the Albany Area Amateur Astronomers, in association with NYS Parks, will hold a public star party at 7:30 pm on Friday, September 18, at the Deerfield Pavilion in Grafton Lakes State Park. At star parties telescopes are set up to provide guests with views of a variety of celestial objects – galaxies, nebular, star clusters, and double stars. Lovely ringed Saturn will be visible low in the southwest during the early part of the star party.
All ages are welcome and there is no admission charge. For directions visit this web site, call the Park office 279-1155, or use the address 100 Grafton Lakes State Park Way, Grafton, NY, 12082.
The star party will be canceled if the skies are mostly cloudy. If weather permits, it will be rescheduled for 7:30 pm on Saturday, September 19. In case of possible cancellation, or for more information, call one of the coordinators, Ray (658-3138) or Bernard (658-9144).
If you look fairly high in the southern sky around 9:00 pm you should spot the bright yellow-white star, Altair. If you’re looking at the right star, it has two fainter stars to either side, one roughly to the lower left and one at about equal distance away on the other side. Altair is the brightest star in Aquila, the Eagle, and its name means “the flying eagle.”
Like most of the brightest stars, Altair shines brightly because it is one of our nearer neighbors, lying at a distance of just under 17 light years. The light you see tonight, traveling 186,000 miles every second, left the star in 1998, the year many watched “Armageddon” and “Deep Impact.” The 1956 science fiction classic, “Forbidden Planet,” was about a visit to Altair 5, a planet orbiting Altair.
The star to the lower left of Altair, Alshain, lies almost 48 light years away, while the one to the upper right, Tarazed, is 390 light years from us. As you can imagine, Tarazed is inherently much brighter than Alshain, but its light is dimmed by its greater distance.
Don’t forget to check next weekend’s Skywatch Line for details on the total lunar eclipse on Sunday night, September 27.