Betelgeuse vs Rigel
Orion carries a blue supergiant at one corner and a red supergiant at the other. Rigel is the B-type star at magnitude 0.18; Betelgeuse the M-type at 0.45, a difference of just over a quarter of a magnitude and about 1.3 times the light. The gap widens once distance enters the account. Rigel lies 862.85 light-years off against 497.95 for Betelgeuse, and its absolute magnitude of −6.93 exceeds Betelgeuse's −5.47 by 1.46 magnitudes — close to four times the intrinsic output. Rigel is therefore both farther and more luminous, and the two only appear comparable because those two facts happen to cancel.
Property comparison
| Property | Betelgeuse | Rigel |
|---|---|---|
| Designation | 58Alp Ori | 19Bet Ori |
| Constellation | Orion | Orion |
| Spectral Class | Class M — M-type (Red) | Class B — B-type (Blue-White) |
| Apparent Magnitude | +0.45 | +0.18 |
| Absolute Magnitude | -5.47 | -6.93 |
| Distance | 498 ly | 863 ly |
| Mass | N/A | N/A |
| Radius | N/A | N/A |
| Temperature | N/A | N/A |
| Luminosity | N/A | N/A |
Full data for each star: Betelgeuse · Rigel
Key differences
Key Differences
- ◆ Rigel is a blue supergiant (spectral type B); Betelgeuse is a red supergiant (spectral type M).
- ◆ Rigel's surface temperature is ~12,100 K — more than three times hotter than Betelgeuse at ~3,600 K.
- ◆ Betelgeuse has a far larger radius (~887 R☉) than Rigel (~79 R☉).
- ◆ Both are in Orion and both are supernova candidates — among the most massive naked-eye stars.
- ◆ Rigel is slightly more intrinsically luminous at ~120,000 L☉ versus Betelgeuse's ~126,000 L☉.
When to Observe
Betelgeuse
Rigel reaches midnight culmination in early December and dominates evening skies from December to March. Its declination of −8° makes it near-universal, visible from almost any inhabited latitude.
Rigel
Betelgeuse culminates at midnight in mid-December, a week after Rigel, and shares the same evening season. At declination +7° it favours northern observers marginally, though it too rises from nearly everywhere.