Bright stars · Orion
Betelgeuse
Alpha Orionis
Details
Magnitude
0.50
Spectral type
M1-M2Ia-ab
Bayer
Alpha Orionis
Distance
640 ly
A vast red supergiant — one of the largest stars visible to the naked eye.
BeginnerWhat is it?
Betelgeuse is a red supergiant star roughly 700 times the diameter of the Sun. If placed at the centre of our Solar System it would engulf the orbit of Jupiter. It is nearing the end of its life and will one day explode as a supernova.
Why observe it?
Betelgeuse is one of the few stars whose surface has actually been resolved by telescopes on Earth. Its brightness varies noticeably over months and years.
What will I see?
Naked eye
A distinctly orange-red bright star in the shoulder of Orion. The colour contrast with blue Rigel below is striking.
Binoculars
The reddish colour is unmistakable — one of the reddest bright stars easily visible.
Reference imagery from long-exposure photography usually shows far more colour and structure than the human eye can see through a telescope.
Observing tips
- Compare Betelgeuse with blue-white Rigel (Orion's foot) to see the temperature difference between stars.
- Best observed in northern-hemisphere winter / southern-hemisphere summer, when Orion is above the horizon.
Interesting facts
- About 650 light-years away.
- Roughly 700 times the Sun's diameter.
- Expected to end its life as a supernova within the next ~100,000 years — likely visible in daylight when it does.