Cool Sun Facts · The Sun among the stars
The Sun is a star: how does it compare?
The Sun is an ordinary star seen from very close. Here it is beside seven others, each number as its source gives it, ranges and disagreements included.
Eight stars side by side
| Star | Surface temperature | Radius (Sun = 1) | Luminosity (Sun = 1) | Distance | Magnitude (V) | Sources |
|---|---|---|---|---|---|---|
| The SunG2 main-sequence dwarf | 5,772 K | 1695,700 km (nominal) | 13.828 × 10²⁶ W (nominal) | 1 au (8.3 light-minutes) | −26.74 | IAU, NASA |
| Alpha Centauri AG2 main-sequence dwarf | 5,790–5,850 K | 1.21measured by interferometry | 1.52 | 4.32 light-years | −0.01A alone; with B, −0.28 (ESA) | Kaler |
| Proxima CentauriM5.5 red dwarf | 3,040 K | 0.15"15 percent the size" | 1/600including its infrared; about 1/600 of the Sunto the eye: 1/18,000 | 4.25 light-years | 11.05 | Kaler, NASA |
| Sirius AA1 main-sequence dwarf | 9,880NASA gives about 10,500 K: sources differ K | 1.75 | 26 | 8.6 light-years | −1.44 | Kaler, ESA |
| VegaA0 main-sequence dwarf | 9,500 (7,950–10,150)an average: 10,150 K at the poles, 7,950 K at the equator K | 2.26–2.75flattened by its spin: 2.26 at the poles, 2.75 at the equator | 36about 36; hard to pin down for a star seen pole-on | 25 light-years | 0.03slightly variable | Kaler, ESA |
| ArcturusK1 giant | 4,290 K | 2625 from its measured angular size | 215including its infraredto the eye: 113 | 37 light-years | −0.05median of a slightly variable star | Kaler, ESA |
| RigelB8 supergiant | 11,500 K | 7473 from its measured angular size | 85,000including its ultraviolet | 860 light-years | 0.18median of a slightly variable star | Kaler, ESA |
| BetelgeuseM1.5 red supergiant | 3,650about K | 667–9893.1 to 4.6 au by different methods and distances, converted here at 215 Suns to the au; its "surface" depends on the colour of light used | 85,000 (85,000–105,000)85,000 at 570 light-years, 105,000 at 640 | 570 (495–640)495 by parallax from space, 640 by radio; 570 a compromise light-years | 0.45 (0.30–1.10)median; it varies from 0.3 to 1.1 (Kaler) | Kaler, ESA |
Temperatures, radii, luminosities and distances are from Jim Kaler's STARS pages, one careful astronomer's summary of the research, each dated; magnitudes from ESA's Hipparcos list where it has them; the Sun's from the IAU's nominal values and NASA's Sun fact sheet. A catalogue value is a good figure at a date, not the last word, and some stars have no single answer: Vega's poles are hotter than its equator, and Betelgeuse's size depends on the colour of light used to measure it. A blank is never filled in.
Compare one with the Sun
Size
How bright it looks, and how bright it is
Both at the same distance
Radius, temperature and luminosity
Its light, as an ideal glowing body
Worked out here with the Stefan–Boltzmann constant and Wien's constant (NIST, CODATA 2022). None of it changes the published values in the table.
Sources
- International Astronomical Union IAU 2015 Resolution B3: nominal solar and planetary conversion constants (Mamajek et al.) (opens in a new tab) for nominal radius 695,700 km, irradiance 1361 W/m², luminosity 3.828×10²⁶ W, effective temperature 5772 K · checked 2 October 2026
- NASA Space Science Data Coordinated Archive Sun Fact Sheet (updated 9 May 2024) (opens in a new tab) for visual magnitude −26.74 at 1 au; luminosity 382.8 × 10²⁴ W; effective temperature 5772 K; radius 695,700 km · checked 2 October 2026
- Jim Kaler, STARS (University of Illinois) Rigil Kentaurus with Proxima Centauri (latest revision 7 November 2016) (opens in a new tab) for Alpha Cen A: G2, 5790 to 5850 K, 1.52 times the Sun, radius 1.21, 4.32 light-years, magnitude −0.01; Proxima: M5.5, 3040 K, 1/600 of the Sun's luminosity (18,000 times dimmer to the eye), 15% of its size, magnitude 11.05 · checked 2 October 2026
- NASA Our Nearest Celestial Neighbor? An Exotic 3-Star System (opens in a new tab) for Proxima Centauri 4.25 light-years away · checked 27 September 2026
- Jim Kaler, STARS (University of Illinois) Sirius (last updated 26 September 2009) (opens in a new tab) for A1 dwarf, 9880 K, 26 times the Sun's luminosity, radius 1.75, 8.6 light-years · checked 2 October 2026
- ESA Hipparcos: The 50 Brightest Stars (opens in a new tab) for V magnitudes: Sirius −1.44, Arcturus −0.05 (median), Vega 0.03, Rigel 0.18, Betelgeuse 0.45 (median), Alpha Centauri −0.28 combined · checked 2 October 2026
- Jim Kaler, STARS (University of Illinois) Vega (last revised 26 June 2009) (opens in a new tab) for A0 dwarf, about 9500 K (7950 at the equator to 10,150 at the poles), diameters 2.26 and 2.75 solar, about 36 times the Sun's luminosity, 25.0 light-years, seen pole-on · checked 2 October 2026
- Jim Kaler, STARS (University of Illinois) Arcturus (opens in a new tab) for K1 giant, 4290 K, 113 times the Sun to the eye and 215 with the infrared, 26 times the Sun's diameter, 37 light-years · checked 2 October 2026
- Jim Kaler, STARS (University of Illinois) Rigel (last updated 26 June 2009) (opens in a new tab) for B8 supergiant, 11,500 K, 85,000 times the Sun, radius 74 (73 measured), 860 light-years · checked 2 October 2026
- Jim Kaler, STARS (University of Illinois) Betelgeuse (last updated 25 January 2011) (opens in a new tab) for M1.5 supergiant, about 3650 K, 495 to 640 light-years, 85,000 to 105,000 times the Sun, radius 3.1 to 4.6 au, magnitude 0.3 to 1.1 · checked 2 October 2026
- NIST Stefan–Boltzmann constant (CODATA 2022) (opens in a new tab) for 5.670374419 × 10⁻⁸ W m⁻² K⁻⁴, exact · checked 2 October 2026
- NIST Wien wavelength displacement law constant (CODATA 2022) (opens in a new tab) for 2.897771955 × 10⁻³ m K, exact · checked 2 October 2026