What’s Up in the Sky – September, 2015
Eclipse of the Harvest Moon Highlights September
September has always been one of my favorite months for observing. Often the skies are clear, there are numerous objects of interest to observe, and it’s the month of the harvest moon. Personally, I have many fond memories of taking my astronomy students out for their first observation. Beginning-of-school enthusiasm along with interest in a brand new subject resulted in enthusiastic students who shared my excitement when looking through the telescope. It helped, of course, that there were many interesting items to observe. I will share some of my favorites with you and encourage you to look for them yourself.
Let’s start with naked-eye objects. The first task is to find an observing site that has a pretty good view of at least one horizon and is away from lights. Look straight up and you will see the Summer Triangle, consisting of Vega, Deneb, and Altair. Use a field guide or your favorite app to identify the constellation each star is in. Looking northwest and you will see Ursa Major, the “Big Dipper”, lower in the sky. Find the three stars that make up the handle of the Dipper and test your eyesight on the middle one by seeing if you can spot its nearby, dim companion. For a very cool sight, aim your telescope at that middle star. I will let you discover this for yourself, but I will say you will be seeing double.
Other good telescopic sights include the double star at the head of Cygnus, the Swan, M57, the Ring Nebula in the constellation Lyra, and M31, the Andromeda Galaxy visible in the eastern sky just to the left of the Great Square of Pegasus. Again, field guides and star charts are available at many bookstores and there are a number of apps to help you in your search. At least now you know what to look for.
The main attraction in September’s sky is, however, the Harvest Moon which is special this year because we will be able to watch as it passes through Earth’s shadow for a total lunar eclipse, the fourth of the current tetrad of four total eclipses of the Moon within two years. Plus, this will be the biggest eclipse you will ever see! That’s because the Moon will be the closest to Earth it has been all year and will appear thirteen percent larger than than it did last April during the last eclipse.
The action begins around 9 p.m. when the Moon first starts to move into the umbra, the dark inner portion of the Earth’s shadow, where the Sun would be totally blocked for a viewer on the Moon. This is the partial eclipse stage of the event and is followed about an hour later by the total eclipse stage, when the Moon is completely engulfed in Earth’s shadow.
During totality, the Moon may appear to be deep red or orange in color. This is due to sunlight being scattered by Earth’s atmosphere, just like during a sunset. An observer on the Moon would see a black Earth ringed by a thin, red glow which lights up the lunar landscape. Don’t miss this beautiful sight up in the sky.
This month in history:
Sept. 1: Pioneer 11 is first spacecraft to fly past Saturn – 1979
Sept. 3: Last two Apollo Moon landings canceled by NASA – 1970
Sept. 8: Voyager 1 launched – 1977
Sept. 20: Wernher von Braun arrives in US – 1945
Sept. 23: Carolyn Herschel discovers NGC 253 – 1783
Sept. 30: End of daily communication with Pioneer 11 – 1995