
Star profile
Eta Herculis
What is Eta Herculis
Eta Herculis marks one corner of the keystone trapezium that forms the body of the hero in the summer sky. A yellow giant, broader and older than the Sun, it lies just over a hundred light-years away. Its warm light, having travelled since Napoleonic times, traces one of four points the ancients called the Falling Keystone, since it tips toward the zenith on the shortest nights of the year.
Where it is and when to see it
Eta Herculis lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is May, when it culminates around midnight.
- From London it never sets and culminates about 77° up.
- From New York it culminates about 88° above the horizon.
- From Sydney it culminates about 17° above the horizon.
It can be seen from anywhere north of 51° S.
It ranks no. 7 in brightness among the 136 stars of Hercules in our catalogue. To find it, start from Kornephoros, the brightest: it lies about 18° away (a fist at arm's length covers about 10°).
The light you see today left it about 110 years ago.
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Astronomical data for Eta Herculis
- Constellation
- Hercules
- Apparent magnitude
- 3.48
- Distance
- 108.7 light years
- Coordinates (J2000)
- RA 250.724° · Dec 38.922°
- Catalogue
- HIP 81833 · HD 150997
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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
- RasalgethiAlpha 1 Herculis2.78
- Zeta Herculis2.81
- SarinDelta Herculis3.12
- Pi Herculis3.16
- Mu Herculis3.42
- Xi Herculis3.70
- Gamma Herculis3.74