Star profile

Propus

Eta Geminorum · Gemini

Variable star

3D likeness based on its real data · class M · ~3,200 K

What is Propus

Propus, in the constellation of Gemini, is a variable red giant 385 light-years from the Earth, one of the more capricious stars of the winter sky in the northern hemisphere. Its name, taken directly from ancient Greek, means «the foot set forward»: it marks with quiet symbolic precision the stride of one of the two celestial twins in their endless joint march. Its light fluctuates slowly, and until a few decades ago it was one of the stars that amateur astronomers patiently watched, with exemplary care, for the smallest shifts in brightness from the balcony at home.

Where it is and when to see it

Propus lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is December, when it culminates around midnight.

From London it culminates about 61° above the horizon.
From New York it culminates about 72° above the horizon.
From Sydney it culminates about 34° above the horizon.

It can be seen from anywhere north of 67° S.

It ranks no. 7 in brightness among the 74 stars of Gemini in our catalogue. To find it, start from Pollux, the brightest: it lies about 21° away (a fist at arm's length covers about 10°).

The light you see today left it about 380 years ago.

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Astronomical data for Propus

Constellation: Gemini
Apparent magnitude: 3.31
Distance: 384.7 light years
Coordinates (J2000): RA 93.719° · Dec 22.507°
Catalogue: HIP 29655 · HD 42995

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Other stars in Gemini

Gemini has 74 stars in Stelvia's catalogue. Here are a few of them.

See all 74 stars in Gemini