Blue-white supergiant · Orion

Alnilam

Also known as: ε Orionis (ε Ori), HIP 26311

mag 1.72,000 light-years

About

Alnilam (ε Orionis) is a blue-white supergiant of magnitude 1.7 in Orion, about 2,000 light-years away.

Alnilam is in the constellation Orion.
Best evenings: around late January it is highest at about 9 pm (10 pm in summer time); a month earlier, two hours later.
Where on Earth: it is seen well, at least 10° up, from south of 79° N.
Star patterns: Orion’s Belt and Sword.

When it rises and sets tonight, how high it climbs and how much the Moon gets in the way are worked out in your browser for your place.

EyesEasy, even from town. It looks blue-white.
Binoculars (10×50)A sharp point; binoculars bring out its colour and the fainter stars around it.
Telescope (6–8 inch)Still a point of light at any magnification — stars are too far away to show a disc. Low in the sky, bright stars twinkle and flash colours.

Stars look the same in any instrument: brighter and sharper, but never bigger.

Proper name	Alnilam
Designation	ε Orionis (ε Ori)
Hipparcos number	HIP 26311
Type	Blue-white supergiant
Spectral type	B0Ia
Colour	Blue-whiteB−V colour index −0.18
Magnitude	1.7The smaller the number, the brighter.
Distance	2,000 light-yearsThe light you see left it around AD 0. Distances this large are uncertain by 10% or more.
Proper motion	0.002″ per year across the sky
Constellation	Orion
Right ascension (J2000)	05h 36m 12.8s
Declination (J2000)	−01° 12′ 07″