The Sky This Week August 23 – 25
The night sky offers many amazing sights for backyard astronomers at every level. Whether your just starting out or your a seasoned veteran, The night sky always has something to see. This week we focus on three things to see in the night sky, with a little help from our friends at EarthSky.0rg.
August 23. 2016’s great Mars and Saturn conjunction
Tonight and tomorrow night – Tuesday and Wednesday, August 23 and 24, 2016 – the red planet Mars is passing in between the planet Saturn and the bright star Antares. That’s after seeing them for months in a triangle pattern on our sky’s dome, then watching the triangle get narrower and narrower as Mars has shifted eastward. Over the next couple of nights, the threesome form a straight line (or very nearly so) on the sky’s dome as darkness falls.
A conjunction is an alignment of objects on the sky’s dome. Mars and Saturn are said to be in conjunction wherever these two worlds lie due north and south of one another in our sky. This happens on August 24.
Conjunctions of Mars and Saturn aren’t particularly rare. Mars’ orbit around the sun takes about two years, so conjunctions happen about that often. The last conjunction of Mars and Saturn happened on August 27, 2014, and the next one will take place on April 2, 2018.
August 24. Great Square of Pegasus points to Andromeda galaxy
Tonight, look for the nearest large spiral galaxy to our Milky Way. It’s becoming well placed for evening viewing from Northern Hemisphere locations. The Great Square of Pegasus is a great jumping off point for finding the famous Andromeda galaxy, also known to astronomers as Messier 31.
As seen from mid-northern latitudes, the Great Square of Pegasus looks like a … well … a big square. Go figure. The Great Square of Pegasus sparkles over the eastern horizon at about 9 p.m. daylight-saving time in mid-August. A month from now – around mid-September – the Great Square returns in the same place in the sky some 2 hours earlier. By autumn, people at northerly latitudes will see the Great Square of Pegasus at nightfall.
August 25. Constellation Cepheus looks like a house
Tonight, see if you can find the constellation Cepheus, which represents a King. This constellation is faint, but its distinctive shape makes it easy to locate if you look in the north on August and September evenings.
At nightfall Cepheus appears to the upper right of Polaris, the North Star. Then this constellation rotates around Polaris in a counter-clockwise direction during the night. It swings high over Polaris after midnight, and then sweeps to the left side of Polaris around dawn.
Cepheus resembles the stick house we all drew as children – and that children today still draw – with a square for the base and a triangle for the roof. In the case of Cepheus, the tip of the roof (a star known as Gamma Cephei, or Errai) points generally northward.
That a wrap for now. Short and sweet, I know, but, the dark window is coming up later this week and I need to get out and collect some photons!