April 27, 2017
Look up with the May 2017 sky map to navigate the stars and constellations in the night sky. On this page is both a color sky map and a black and white printable map to bring outside!
Just click here or on the image below to open the printable map—then bring outside!
The night sky is divided into 88 constellations, per an agreement by the member countries of the International Astronomical Union (IAU). The constellation boundaries were formalized by the IAU in 1922, and every star in the sky lies within one of the 88 regions.
Sometimes, stars within constellations form distinctive patterns or shapes that have earned them unofficial names of their own, apart from the name of the constellation. These entirely unofficial star patterns are known as “asterisms,” and this month’s Sky Map is loaded with them.
In May, the sky is not fully dark until about 11:00 P.M. Because it takes your eyes 20 to 30 minutes to become fully dark-adapted, you should go outside at about 10:30 to prepare for stargazing. To preserve your night vision, avoid streetlights and conventional flashlights. Veteran stargazers use red light only, which does not harm your night vision like other colors of light. You can fashion a red flashlight by placing red plastic or a red balloon over the end of a regular flashlight.
When you are fully prepared, look due east and find the four-sided Keystone asterism in the constellation Hercules. The Keystone is so named because its shape resembles the keystone at the center of an arched doorway or stone bridge. The Keystone asterism will be the center of our asterism tour.
To the left of the Keystone is a smaller four-sided asterism comprising the head of Draco the Dragon. Below the Head of the Dragon, near blazing Vega, is yet another four-sided figure, the exquisite Parallelogram in Lyra, the Lyre.
May Sky Map
Click here or on image below to enlarge this map (PDF).
Sky map produced using Chris Marriott’s Skymap Pro
Draco is not the only reptile on this month’s map. Look to the right of the Keystone for the small triangle that forms the head of Serpens, the Serpent, whose body slithers to the right and downward. Serpens is unique among the 88 constellations because it is split into two parts. If you look near the bottom of the map, you’ll see Serpens’s other half—its tail. For a better look, stay up until 1:30 or 2:00 a.m., when the tail of Serpens will rise higher in the sky and be much easier to see.
To the upper right of the Keystone sits the constellation Corona Borealis, the Northern Crown. Its brightest stars form a lovely semicircle that I call the Tiara. In a dark sky, the Tiara is a beautiful, delicate sight. In mythology, the stars that comprise the Tiara are the diamonds of a royal crown worn by the Cretan princess Ariadne.
Directly above the Tiara is the Kite asterism in the constellation Boötes, the Herdsman. It’s a lopsided Kite, to be sure, and it’s lying on its side from our point of view. Nevertheless, once you recognize the shape, you always see a Kite when you gaze in the direction of Boötes.
Also lying sideways, in the lower left near the horizon, is the Northern Cross asterism. The Northern Cross forms the main body of Cygnus, the Swan. Like all objects on the eastern horizon, Cygnus will rise higher in the sky as the night wears on. In fact, by about 2:00 a.m., the Northern Cross will be located right where the Keystone sits at 11:00 p.m.!
Enjoy astronomy? Check out Bob Berman’s column, “This Week’s Amazing Sky.”