Herculesis a large but not prominent constellation depicting the hero of Greek Myth, Hercules lies between the bright stars Arcturus and Vega. The body of Hercules is inverted in the sky, the head being marked by Alpha Herculis, in the south, and the feet by the stars to the north. Hercules was ordered by King Eurystheus of Mycenae to perform 12 labors, one of which was to slay a dragon (marked by adjacent Draco). Hercules is depicted resting on his right knee, with his left foot on the dragon's head. The constellation features the brightest globular cluster in northern skies, M13, and some notable double stars. Its brightest star is Beta Herculis, magnitude 2.8.
Highest in the Sky: June to August
Size Ranking: 5th
Coverage Area: 1,125 Sq. Degrees
Right Acension: 17 hours
Visibility: 90°N to 39°S
Alpha Herculis: Double star
Rho Herculis: Optical Double star
M13: Hercules Cluster
The Propeller: Multiple star system
M92: Globular cluster
NGC 6207: Spiral galaxy
NGC 6210: Planetary nebula
95 Herculis: Red giant star
Ras Algethi, Alpha Herculis
Rutilicus, Beta Herculis
Sarin, Delta Herculis
Marfik, Kappa Herculis
Maasym, Lambda Herculis
Kajam, Omega Herculis
Best Viewed Objects/Stars
Alpha Herculis (Rasalgethi)
A red giant of variable brightness. It ranges between 3rd and 4th magnitudes, with no set period, as a result of fluctuations in its size. A small telescope shows a companion of magnitude 5.4. Hercules is depicted kneeling, and the name Rasalgethi is derived fron an Arabic term meaning "the kneelers head."
A optical double star. The two components of magnitudes 4.6 and 5.4 can be separated with a small telescope with high magnification.
A silver and gold pair of stars of magnitudes 5.0 and 5.2, divisible through a small telescope.
A pair of almost identical white stars, both of magnitude 5.8, that can be separated with a small telescope. The two stars do not form a true binary.
The brightest globular cluster in the northern sky. Under dark skies, it appears to the naked eye like a hazy star. Binoculars show it clearly, about half the apparent size of the full Moon, and a small telescope shows its brightest stars. It is 25,000 light-years away.
A globular cluster, fainter and smaller than M13 but still worthy of attention. Binoculars are needed to find it, and a telescope of moderate aperture will show its stars.