Tonight, try locating one of the coolest constellations up there. The constellation Hercules the Kneeling Giant can be seen ascending in the east-northeast on these Northern Hemisphere spring evenings. You can find Hercules in between two brilliant stars: Arcturus and Vega, which, by the way, lies near the radiant point for the ongoing Lyrid meteor shower. The chart at the top of this post shows the sky for around 10 to 11 p.m. local time, when the constellation Hercules, and the two bright stars so essential for finding it, are well up in the northeastern to eastern sky.
Arcturus is in the constellation Bootes, and Vega is in the constellation Lyra. A line between them passes through what is known as the Keystone in Hercules.
At nightfall, Vega may still be below in your horizon. If so, look for Hercules below the star Arcturus.
The Keystone in Hercules is a squarish figure in the center of the constellation. This sky pattern is an asterism, or noticeable pattern within a larger constellation.
The Keystone is a helpful pattern for more reasons than one. First, it’s noticeable on the sky’s dome, so can lead your eye to Hercules.
Also, the Keystone in Hercules can help you find the most fascinating telescopic object within the boundaries of this constellation. This object is a globular star cluster known to stargazers as M13 or the Great Cluster in Hercules. It’s barely visible the eye alone in the darkest of skies.
Binoculars show M13 as a nebulous star-like patch of light. And telescopes show stars both on the periphery of the cluster and toward its center.
This beautiful object is one of the galaxy’s oldest inhabitants. It’s a tightly packed spherical collection of about one million stars.
Remember, Vega closely marks the radiant point of the Lyrid meteor shower. This annual April shower is active between April 16 and 25 each year. In 2015, the peak is expected to peak on the mornings of April 22 and 23.
Bottom line: Use the brilliant stars Arcturus and Vega to find the constellation Hercules tonight!