Star profile

Epsilon Herculis

3D likeness based on its real data · class A · ~8,500 K

What is Epsilon Herculis

Epsilon Herculis is one of the four corners of the Keystone, the luminous trapezoid that defines the torso of Hercules in the northern summer sky. The faintest of the four, it is a white A0 star at 155 light-years, in fact a spectroscopic binary whose components reveal themselves only through the sway of their spectral lines. Without it, the celestial hero's geometry would collapse.

Where it is and when to see it

Epsilon 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 culminates about 69° above the horizon.
From New York it culminates about 80° above the horizon.
From Sydney it culminates about 25° above the horizon.

It can be seen from anywhere north of 59° S.

It ranks no. 15 in brightness among the 136 stars of Hercules in our catalogue. To find it, start from Kornephoros, the brightest: it lies about 12° away (a fist at arm's length covers about 10°).

The light you see today left it about 160 years ago.

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Astronomical data for Epsilon Herculis

Constellation: Hercules
Apparent magnitude: 3.92
Distance: 155.0 light years
Coordinates (J2000): RA 255.072° · Dec 30.926°
Catalogue: HIP 83207 · HD 153808

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Other stars in Hercules

Hercules has 136 stars in Stelvia's catalogue. Here are a few of them.

See all 136 stars in Hercules