Star profile
Rasalgethi
Alpha 1 Herculis · Hercules
Variable starWhat is Rasalgethi
Rasalgethi, «the head of the kneeling one», crowns the figure of Hercules in the deep red of its M class. It is a supergiant several times wider than the orbit of Mars and one of the broadest variables in the sky: its brightness breathes over months as its huge atmosphere pulses in slow waves. Its light crosses 359 light years to reach earthly telescopes.
Where it is and when to see it
Rasalgethi lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is June: the Sun sits at the opposite point of the sky and the star culminates around midnight. How high it climbs above the horizon depends on the latitude you watch from.
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Astronomical data for Rasalgethi
- Constellation
- Hercules
- Apparent magnitude
- 2.78
- Distance
- 359.6 light years
- Coordinates (J2000)
- RA 258.662° · Dec 14.390°
- Catalogue
- HIP 84345 · HD 156014
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Other stars in Hercules
Hercules has 136 stars in Stelvia's catalogue. Here are a few of them.
- KornephorosBeta Herculis2.78
- Zeta Herculis2.81
- SarinDelta Herculis3.12
- Pi Herculis3.16
- Mu Herculis3.42
- Eta Herculis3.48
- Xi Herculis3.70
- Gamma Herculis3.74