Hercules
Origin
Hercules is a northern hemisphere constellation but it is visible to many observers south of the equator as well. Hercules is named after the hero of Roman mythology (the Greek version is Heracles). Hercules is one of the 48 constellations cataloged by the second-century astronomer Ptolemy. Hercules is the fifth-largest constellation by size. Hercules is best observed in the northern hemisphere from late spring until early fall.
Bright Stars
Alpha Herculis, or Rasalgethi, is a triple star system that varies from magnitude 2.7 to 4.0. Two of the stars can be resolved in small telescopes (the third is only detectable through spectroscopy). The system is located 359 light-years from Earth. Kornephoros (Beta Herculis) is the brightest star in Hercules. Kornephoros is a yellow giant shining at magnitude 2.8 and located 148 light-years distant. Delta Herculis is a double star that can be resolved in small telescopes. The primary is a magnitude 3.1 blue-white star with a much dimmer magnitude-8.2 companion. Gamma Herculis is another good double star for small telescopes. The primary is a white giant of magnitude 3.8, 195 light-years from Earth, with a 10th-magnitude secondary star.
Photo of the constellation Hercules produced by NOIRLab in collaboration with Eckhard Slawik, a German astrophotographer.
The annotations are from a standardized set of 88 western IAU constellations and stick figures from Sky & Telescope. Please find here a non-annotated version of the image.
Credit: E. Slawik/NOIRLab/NSF/AURA/M. Zamani
Latin name
English name
Hercules
Pronunciation
HER-kyou-lee
Abbreviation
Her
Notable Objects
Hercules is home to one of the best globular clusters in the sky, Messier 13. Messier 13 shines at 6th magnitude and is visible to the naked eye from a dark site. Messier 13 contains 300,000 stars and covers an area of the sky almost as big as the full Moon! Messier 13 is 25,000 light-years distant. A more compact globular cluster in Hercules is Messier 92. Messier 92 shines at magnitude 6.4 and lies 26,000 light-years from Earth. NGC 6229 is a 9th-magnitude planetary nebula 4000 light-years from Earth and visible through small telescopes.
