Star profile

Sigma Orionis

Hot blue star

3D likeness based on its real data · class O · ~30,000 K

What is Sigma Orionis

Sigma Orionis presides over a young cluster of several hundred forming stars, just southeast of Orion's Belt and a stone's throw from the Horsehead Nebula it helps to backlight. Its primary is one of the rare O-type stars within naked-eye reach—a hot blue lantern marshalling a swarm of still-young suns around it. The light crosses more than a thousand years before it reaches the eye.

Where it is and when to see it

Sigma Orionis lies in the southern 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 36° above the horizon.
From New York it culminates about 47° above the horizon.
From Sydney it culminates about 59° above the horizon.

It can be seen from anywhere south of 87° N.

It ranks no. 15 in brightness among the 128 stars of Orion in our catalogue. To find it, start from Rigel, the brightest: it lies about 8° away (a fist at arm's length covers about 10°).

The light you see today left it about 1,100 years ago.

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Astronomical data for Sigma Orionis

Constellation: Orion
Apparent magnitude: 3.77
Distance: 1073.0 light years
Coordinates (J2000): RA 84.687° · Dec -2.600°
Catalogue: HIP 26549 · HD 37468

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Other stars in Orion

Orion has 128 stars in Stelvia's catalogue. Here are a few of them.

See all 128 stars in Orion