Size comparison: Betelgeuse vs Stephenson 2-18

Size comparison between two super giants, Betelgeuse and Stephenson 2-18.

Stephenson 2-18 is also a super red giant. This star is located in the constellation of the Shield of Sobieski, it is twice as large as Betelgeuse. We do not know its age, nor the gravity on its surface. It is one of the largest and most luminous stars known to date. It would take 9 hours to cross this star, considering that we are traveling at the speed of light.

Object	Betelgeuse	Stephenson 2-18
Type	Star, red supergiant	Star, red supergiant
Diameter	1,235,310,708 km	2,994,270,600 km
Mean radius	617,655,354 km	1,497,135,300 km
Mass	2.29 × 1031 kg	7.9 × 1031 kg
Surface temperature (average)	3,500 K 3,227 °C 5,840 °F	3,200 K 2927 °C 5300 °F
Surface gravity	-0.001 m/s²	0.04 m/s²
Circumference	1.2 billion km	9.4 billion km
Surface area	1.5 × 1018 km2	2.8 × 1019 km2
Volume	9.87 × 1026 km3	1.4 × 1028 km3
Atmosphere composition	hydrogen, helium	hydrogen, helium
Crust composition	hydrogen, helium	hydrogen, helium
Sun distance	724 light years	18,900 light years
Luminosity	5.73 × 1031 W	1.66 × 1032 W
Photosphere temperature	3,590 K	3,200 K
Spectral classification	M1–M2 Ia–ab	M6
Right ascension	05h 55m 10.29s	18h 39m 02.3709s
Declination	+07° 24′ 25.3″	−06° 05′ 10.5357″

Note: if one of the objects is not visible, it just means that it is too tiny to be displayed compared to the other one.