Betelgeuse — Variable Star in Orion
HIP 27989; Alpha Orionis; 58 Orionis
About Betelgeuse
Description
Betelgeuse is a red supergiant of spectral type M1-2Ia-Iab at magnitude 0.5 (variable between about 0.0 and 1.6) in Orion. Located roughly 650 light-years from Earth, it is one of the largest stars known — with a diameter of roughly 1,000 times the Sun's, if placed at the center of our solar system its surface would extend beyond the orbit of Mars. It is a semi-regular variable star with multiple overlapping pulsation periods.
Observing Tips
Betelgeuse is the unmistakable orange-red star at Orion's upper-left shoulder. Its deep color contrasts dramatically with blue-white Rigel diagonally opposite. The color is obvious to the naked eye and striking in binoculars. Watch its brightness over months — it varies noticeably. Best observed December through March.
History
The name Betelgeuse is a corruption of the Arabic 'yad al-jawza,' meaning 'the hand of the central one.' Its enormous size was first measured interferometrically by Albert Michelson and Francis Pease in 1920, making it the first star (beyond the Sun) to have its diameter directly measured. The 'Great Dimming' of late 2019 to early 2020 made worldwide headlines.
Fun Facts
Betelgeuse is expected to explode as a Type II supernova sometime within the next 100,000 years. When it does, it will briefly outshine the full Moon and be visible in daylight. The Great Dimming of 2019-2020 was caused by a mass ejection that cooled into a dust cloud, temporarily blocking about two-thirds of the star's light.
Observe
1Physical Properties
2Position & Identifiers
3How easy to follow?
| Equipment | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| Naked eye Naked eye | Medium+ | Medium+ | Medium+ |
| 50 mm finder 50mm finder | Medium+ | Medium+ | Medium+ |
| 150 mm telescope 150mm scope | Medium+ | Medium+ | Medium+ |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Survey Image
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6Light Curve
7Comparison Stars for Betelgeuse (0.4–1.3)
Nearby stable stars for estimating brightness (AAVSO)
Explore
9
Size Comparison
10
Compare Stars
11
Spectral Classification
12
Hertzsprung-Russell Diagram
13
Stellar Lifecycle
14
Blackbody Spectrum
15
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
16
Stellar Fusion
Discover
17Stellar Notes
18
Light Travel Time Machine
19
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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