Our sky map for September 2016 is a free and printable star chart to see stars and constellations in the night sky, from The Old Farmer’s Almanac.
Discover the Summer Triangle
This article and sky map is by astronomer Jeff DeTray from AstronomyBoy.com.
Although the calendar says that we are only a few weeks from the beginning of autumn, it’s still summertime in the night sky. The distinctive Summer Triangle can help you to navigate the heavens on warm September nights.
Click-and-Print Sky Map
Just click here or on the image below to open the printable map—then bring outside!
When you face westward at this time of year, the night sky is dominated by three bright stars: Altair, Vega, and Deneb. These three form the Summer Triangle, as illustrated in purple on this month’s sky map.
Look nearly straight up to find the bright star Deneb, which sits at the top of the Northern Cross asterism (unofficial star pattern), itself a part of the large constellation Cygnus, the Swan. The Northern Cross is one of those asterisms that, once seen, is easily recognized in the future.
Directly below Deneb you’ll find the even brighter star Vega, in the constellation Lyra, the Lyre. Moviegoers were introduced to Vega by the 1997 film Contact, starring Jodie Foster. In the movie, a planet orbiting Vega was home to the first alien civilization to contact Earth. To the left of Vega is a small group of four stars that form the Lyre, a delicate, near-perfect parallelogram.
Look to the left to find Altair, the third member of the Summer Triangle, in the constellation Aquila, the Eagle. Altair is midway in brightness between Deneb and Vega. Its name derives from an Arabic phrase that translates as “the flying eagle.” So, both the star and its constellation have roughly the same name. As interstellar distances go, Altair is a close neighbor—a mere 17 light-years (99.9 trillion miles) from us!
The three stars of the Summer Triangle are helpful for guiding you to other celestial sights. Following the line from Altair rightward past Vega brings you to the head of Draco, the Dragon. Once you have spotted its head, try to follow the sinuous body of the Dragon that slants upward, then bends downward and curls under the Little Dipper.
Below Vega you will find the sprawling constellation Hercules, the mighty hero of Roman and Greek mythology. (The Greeks called him Heracles.) Four of the brighter stars of Hercules form the nicely symmetrical Keystone asterism. The Keystone is often visible even when most other stars in Hercules are obscured by streetlights and other manmade light pollution.
Just beneath the Keystone is the lovely constellation Corona Borealis, the Northern Crown. To me, Corona Borealis more closely resembles a tiara or, if you are a Harry Potter fan, the Lost Diadem of Ravenclaw. In Harry’s magical world, the Diadem was said to grant wisdom to its wearer and to carry the famous inscription: “Wit beyond measure is man’s greatest treasure.”
Just to the right of Corona Borealis and very near the horizon stands the kite-shape form of Boötes, the Herdsman. You will need a dark location that is free of trees and buildings to get a good view of the Kite and its brightest star, Arcturus.
September nights are among the most pleasant of the year. Plan to spend at least one of them enjoying the Summer Triangle and the many sights within and around it.
September 2016 Sky Map
Click here or on image below to enlarge this map (PDF).
Sky map produced using Chris Marriott’s Skymap Pro
Enjoy astronomy? Check out “This Week’s Amazing Sky” column!