{"id":"star-sizes","reviewedAt":"2026-10-01T00:00:00+00:00","minRatio":1.1,"start":"sun","items":[{"id":"uy-scuti","name":"UY Scuti","category":"Red supergiant","metres":2376511200000,"basis":"measured","dimension":"diameter","low":2109362400000,"high":2643660000000,"minRatio":2.5,"sizeLabel":"2.38 billion km","altLabel":"1,710 × the Sun’s diameter","measure":"Radius 1,708 ± 192 solar radii · depends on its uncertain distance","note":"Its size scales with its distance, which is uncertain, so it is only paired with stars less than 40% of its size.","source":"https://arxiv.org/abs/1305.6179","sourceLabel":"Arroyo-Torres et al. 2013, Astronomy & Astrophysics 554, A76","quote":"5.48 ± 0.10 mas (R=1708 ± 192 R⊙) for UY Sct","image":"/scale/stars/uy-scuti.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"vy-canis-majoris","name":"VY Canis Majoris","category":"Red supergiant","metres":1975788000000,"basis":"measured","dimension":"diameter","low":1808820000000,"high":2142756000000,"sizeLabel":"1.98 billion km","altLabel":"1,420 × the Sun’s diameter","measure":"Radius 1,420 ± 120 solar radii","source":"https://arxiv.org/abs/1203.5194","sourceLabel":"Wittkowski et al. 2012, Astronomy & Astrophysics","quote":"this estimate corresponds to a radius of 1420 +/- 120 Rsun","image":"/scale/stars/vy-canis-majoris.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"betelgeuse","name":"Betelgeuse","category":"Red supergiant","metres":1063029600000,"basis":"measured","dimension":"diameter","low":976762800000,"high":1224432000000,"sizeLabel":"1.06 billion km","altLabel":"764 × the Sun’s diameter","measure":"Radius 764 solar radii (+116/−62) · model estimate","source":"https://arxiv.org/abs/2006.09837","sourceLabel":"Joyce et al. 2020, The Astrophysical Journal 902","quote":"a precise prediction for the star's radius: 764 (+116/−62) R☉","image":"/scale/stars/betelgeuse.webp","imageSource":"https://commons.wikimedia.org/wiki/File:Betelgeuse_captured_by_ALMA.jpg","imageCredit":"ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella","imageLicense":"CC BY 4.0","imageFile":"Betelgeuse captured by ALMA.jpg","imageNote":"ALMA telescope image of its surface"},{"id":"antares","name":"Antares","category":"Red supergiant","metres":973980000000,"basis":"about","dimension":"diameter","minRatio":1.2,"sizeLabel":"About 970 million km","altLabel":"about 700 × the Sun’s diameter","measure":"About 700 times the Sun’s diameter","source":"https://www.eso.org/public/news/eso1726/","sourceLabel":"ESO","quote":"Antares now has a mass about 12 times that of the Sun and a diameter about 700 times larger than the Sun’s.","image":"/scale/stars/antares.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"deneb","name":"Deneb","category":"Blue-white supergiant","metres":282454200000,"basis":"measured","dimension":"diameter","low":258800400000,"high":306108000000,"sizeLabel":"282 million km","altLabel":"203 × the Sun’s diameter","measure":"Radius 203 ± 17 solar radii","source":"https://arxiv.org/abs/0712.0040","sourceLabel":"Schiller & Przybilla 2008, Astronomy & Astrophysics","quote":"R = 203 +/- 17 R_sun","image":"/scale/stars/deneb.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"rigel","name":"Rigel","category":"Blue supergiant","metres":109781460000.00002,"basis":"measured","dimension":"diameter","low":99485100000.0,"high":120077820000.0,"sizeLabel":"110 million km","altLabel":"78.9 × the Sun’s diameter","measure":"Radius 78.9 ± 7.4 solar radii","source":"https://arxiv.org/abs/1201.0843","sourceLabel":"Moravveji et al. 2012, The Astrophysical Journal 747, 108","quote":"yields R = 78.9 ± 7.4 R⊙","image":"/scale/stars/rigel.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"aldebaran","name":"Aldebaran","category":"Orange giant","metres":61499880000.00001,"basis":"measured","dimension":"diameter","low":60247619999.99999,"high":62752140000.0,"sizeLabel":"61.5 million km","altLabel":"44.2 × the Sun’s diameter","measure":"Radius 44.2 ± 0.9 solar radii","source":"https://arxiv.org/abs/astro-ph/0502181","sourceLabel":"Richichi & Roccatagliata 2005, Astronomy & Astrophysics","quote":"The corresponding limb-darkened value is 20.58+-0.03 milliarcseconds, or 44.2+-0.9 R(sun).","image":"/scale/stars/aldebaran.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"arcturus","name":"Arcturus","category":"Orange giant","metres":35341560000.0,"basis":"measured","dimension":"diameter","low":35063280000.0,"high":35619840000.0,"sizeLabel":"35.3 million km","altLabel":"25.4 × the Sun’s diameter","measure":"Radius 25.4 ± 0.2 solar radii","source":"https://arxiv.org/abs/1109.4425","sourceLabel":"Ramírez & Allende Prieto 2011, The Astrophysical Journal 743, 135","quote":"R = 25.4+/-0.2 Rsun","image":"/scale/stars/arcturus.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"vega","name":"Vega","category":"White main-sequence star","metres":3792956400.0,"basis":"measured","dimension":"diameter","low":3347708400.0,"high":3801304800.0000005,"sizeLabel":"3.79 million km","altLabel":"2.73 × the Sun’s diameter","measure":"Equatorial radius 2.726 solar radii · 2.418 at the poles","source":"https://arxiv.org/abs/1211.6055","sourceLabel":"Monnier et al. 2012, The Astrophysical Journal Letters 761, L3","quote":"R pol (R⊙) 2.418 ± 0.012 … R eq (R⊙) 2.726 ± 0.006","image":"/scale/stars/vega.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"procyon-a","name":"Procyon A","category":"Yellow-white star","metres":2849587200.0,"basis":"measured","dimension":"diameter","low":2814802200.0,"high":2884372200.0,"sizeLabel":"2.85 million km","altLabel":"2.05 × the Sun’s diameter","measure":"Diameter 2.048 ± 0.025 times the Sun’s","source":"https://arxiv.org/abs/astro-ph/0309148","sourceLabel":"Kervella et al. 2004, Astronomy & Astrophysics 413, 251","quote":"this gives a linear diameter of 2.048 +/- 0.025 D_sun","image":"/scale/stars/procyon-a.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"sirius-a","name":"Sirius A","category":"White main-sequence star","metres":2380685400.0,"basis":"measured","dimension":"diameter","low":2362597200.0,"high":2398773600.0,"sizeLabel":"2.38 million km","altLabel":"1.71 × the Sun’s diameter","measure":"Diameter 1.711 ± 0.013 times the Sun’s","source":"https://arxiv.org/abs/astro-ph/0306604","sourceLabel":"Kervella et al. 2003, Astronomy & Astrophysics 408, 681","quote":"this translates into a linear diameter of 1.711 +/- 0.013 Dsun","image":"/scale/stars/sirius-a.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"alpha-centauri-a","name":"Alpha Centauri A","category":"Yellow main-sequence star","metres":1702238760.0,"basis":"measured","dimension":"diameter","low":1694864340.0,"high":1709613179.9999998,"sizeLabel":"1.7 million km","altLabel":"1.22 × the Sun’s diameter","measure":"Radius 1.2234 ± 0.0053 solar radii","source":"https://arxiv.org/abs/1610.06185","sourceLabel":"Kervella et al. 2017, Astronomy & Astrophysics 597, A137","quote":"we derive linear radii of RA = 1.2234 +/- 0.0053 Rsun (0.43%) and RB = 0.8632 +/- 0.0037 Rsun","image":"/scale/stars/alpha-centauri-a.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"sun","name":"The Sun","category":"Yellow main-sequence star","metres":1391400000,"basis":"measured","dimension":"diameter","sizeLabel":"1.39 million km","altLabel":null,"measure":"Diameter, from the volumetric mean radius","source":"https://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html","sourceLabel":"NASA Sun Fact Sheet","quote":"Volumetric mean radius (km) 695,700","image":"/scale/sun.webp","imageSource":"https://images.nasa.gov/details/GSFC_20171208_Archive_e002035","imageCredit":"NASA/GSFC","imageLicense":"Public domain (NASA)","imageNote":"Ultraviolet observation"},{"id":"alpha-centauri-b","name":"Alpha Centauri B","category":"Orange main-sequence star","metres":1201056480.0,"basis":"measured","dimension":"diameter","low":1195908300.0,"high":1206204660.0,"sizeLabel":"1.2 million km","altLabel":"0.863 × the Sun’s diameter","measure":"Radius 0.8632 ± 0.0037 solar radii","source":"https://arxiv.org/abs/1610.06185","sourceLabel":"Kervella et al. 2017, Astronomy & Astrophysics 597, A137","quote":"we derive linear radii of RA = 1.2234 +/- 0.0053 Rsun (0.43%) and RB = 0.8632 +/- 0.0037 Rsun","image":"/scale/stars/alpha-centauri-b.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"epsilon-eridani","name":"Epsilon Eridani","category":"Orange main-sequence star","metres":1029636000.0,"basis":"measured","dimension":"diameter","low":1015722000.0,"high":1043550000.0,"sizeLabel":"1.03 million km","altLabel":"0.74 × the Sun’s diameter","measure":"Radius 0.74 ± 0.01 solar radii","source":"https://arxiv.org/abs/1112.0447","sourceLabel":"Baines & Armstrong 2012, The Astrophysical Journal 748, 72","quote":"calculate the star’s physical radius: 0.74 ± 0.01 R⊙","image":"/scale/stars/epsilon-eridani.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"proxima-centauri","name":"Proxima Centauri","category":"Red dwarf","metres":214553880.0,"basis":"measured","dimension":"diameter","low":186447600.0,"high":220815180.0,"sizeLabel":"215,000 km","altLabel":"0.154 × the Sun’s diameter","measure":"Radius 0.1542 ± 0.0045 solar radii · interferometry: 0.141 ± 0.007","source":"https://arxiv.org/abs/1611.03495","sourceLabel":"Kervella et al. 2017, Astronomy & Astrophysics 598, L7","quote":"The radius-MKs relation gives R Prox = 0.1542 ± 0.0045 R⊙, which is slightly larger (+1.6σ) than the interferometrically measured value of R Prox = 0.141 ± 0.007 R⊙","image":"/scale/stars/proxima-centauri.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"jupiter","name":"Jupiter","category":"Planet","metres":142984000,"basis":"measured","dimension":"diameter","sizeLabel":"142,984 km","altLabel":"0.103 × the Sun’s diameter","measure":"Equatorial diameter","source":"https://nssdc.gsfc.nasa.gov/planetary/factsheet/","sourceLabel":"NASA Planetary Fact Sheet","quote":"Diameter (km) … 142,984","image":"/scale/jupiter.webp","imageSource":"https://images.nasa.gov/details/PIA04866","imageCredit":"NASA/JPL/Space Science Institute","imageLicense":"Public domain (NASA)","imageNote":"Cassini spacecraft"},{"id":"trappist-1","name":"TRAPPIST-1","category":"Red dwarf","metres":165854880.0,"basis":"measured","dimension":"diameter","low":164046060.0,"high":167663700.0,"sizeLabel":"166,000 km","altLabel":"0.119 × the Sun’s diameter","measure":"Radius 0.1192 ± 0.0013 solar radii","source":"https://arxiv.org/abs/2010.01074","sourceLabel":"Agol et al. 2021, The Planetary Science Journal","quote":"R [R⊙] 0.1192 ± 0.0013 This paper","image":"/scale/stars/trappist-1.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"earth","name":"Earth","category":"Planet","metres":12756000,"basis":"measured","dimension":"diameter","sizeLabel":"12,756 km","altLabel":"1/109 of the Sun’s diameter","measure":"Equatorial diameter","source":"https://nssdc.gsfc.nasa.gov/planetary/factsheet/","sourceLabel":"NASA Planetary Fact Sheet","quote":"Diameter (km) … 12,756","image":"/scale/earth.webp","imageSource":"https://images.nasa.gov/details/PIA18033","imageCredit":"NASA","imageLicense":"Public domain (NASA)","imageNote":"Satellite mosaic"},{"id":"sirius-b","name":"Sirius B","category":"White dwarf","metres":12000000,"basis":"about","dimension":"diameter","minRatio":1.2,"sizeLabel":"About 12,000 km","altLabel":"about 1/116 of the Sun’s diameter","measure":"Diameter measured with the Hubble Space Telescope","source":"https://esahubble.org/news/heic0516/","sourceLabel":"ESA/Hubble","quote":"Sirius B has a diameter of 12,000 kilometres, less than the size of Earth","image":"/scale/stars/sirius-b.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true},{"id":"psr-j0030","name":"PSR J0030+0451","category":"Neutron star","metres":25420.0,"basis":"measured","dimension":"diameter","low":23040.0,"high":27700.0,"sizeLabel":"25.4 km","altLabel":"1/54,700 of the Sun’s diameter","measure":"Equatorial radius 12.71 km (+1.14/−1.19)","source":"https://arxiv.org/abs/1912.05702","sourceLabel":"Riley et al. 2019, The Astrophysical Journal Letters 887, L21 (NASA NICER)","quote":"The inferred mass M and equatorial radius R_eq are, respectively, 1.34 (+0.15/−0.16) M⊙ and 12.71 (+1.14/−1.19) km","image":"/scale/stars/psr-j0030.svg","imageNote":"Illustration · colour suggests the surface temperature","illustration":true}]}