Star profile

Alnilam

Epsilon Orionis · Orion

Variable star

3D likeness based on its real data · class B · ~15,000 K

What is Alnilam

Alnilam is the central pearl of Orion's Belt, a blue B-type supergiant whose brilliance travels nearly two thousand years before reaching us. The light seen tonight set out while Rome was still deciding the fate of the Mediterranean. Its Arabic name, «An-Nizam», means «the string of pearls», a nod to the three aligned stars that for centuries guided sailors and desert caravans. It is also subtly variable, a slow pulse cloaked in a faint reflection nebula of cosmic dust.

Where it is and when to see it

Alnilam 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 37° above the horizon.
From New York it culminates about 48° above the horizon.
From Sydney it culminates about 57° above the horizon.

It can be seen from anywhere south of 89° N.

It ranks no. 4 in brightness among the 128 stars of Orion in our catalogue. To find it, start from Rigel, the brightest: it lies about 9° away (a fist at arm's length covers about 10°).

The light you see today left it about 2,000 years ago.

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Astronomical data for Alnilam

Constellation: Orion
Apparent magnitude: 1.69
Distance: 1977.0 light years
Coordinates (J2000): RA 84.053° · Dec -1.202°
Catalogue: HIP 26311 · HD 37128

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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