Since Betelgeuse began dimming again, readers have asked us which of Orion’s two supergiants will go supernova first. Betelgeuse is a red supergiant about 750 times wider than the Sun and roughly 550 light-years away; Rigel is a blue supergiant about 74 times wider, 18 to 24 solar masses and around 850 light-years away. Rigel’s pulsations hint it may already have been a red supergiant, while its chemistry says it is still on the way, and its luminosity estimates range from 61,500 to 363,000 Suns. Our take: nobody can name a winner yet, and both are safely far away.
750 vs 74times the Sun’s radius
550 / 850light-years away
≈ 160 lya supernova must be closer than this to harm Earth
Orion holds two of the brightest massive stars in our sky: orange-red Betelgeuse at the Hunter’s shoulder and blue-white Rigel at his foot. Both are supergiants that will one day end as supernovae. Since Betelgeuse started dimming again in August 2026, many of you have asked us the same thing: which one goes first?
The honest answer is that nobody can say yet. But the reasons why are a great way to see how astronomers read the lives of stars.
The question came from a viewer under our Betelgeuse Reel on Instagram, who bet on Rigel: it may already be past its red-supergiant phase, may have lost more than 30% of its birth mass, shows non-radial pulsations and could emit around 363,000 Suns in total. Good points, and none of them settled; we go through each one below.
Betelgeuse: huge, restless, and probably not in a hurry
Betelgeuse is a red supergiant about 750 times wider than the Sun, with 16.5 to 19 solar masses, roughly 550 light-years away. It pulsates with periods of about 400 and 185 days, on top of a long cycle of about 2,100 days (5.8 years) that is now linked to its faint companion Siwarha, imaged in 2025. Most models (Joyce et al. 2020) put it early in helium burning, more than 100,000 years before collapse. A 2023 study argued it might already be burning carbon, which would bring the end much closer, but that idea is disputed.
Betelgeusered supergiant · ≈ 750 R☉ · ≈ 550 ly
Rigelblue supergiant · ≈ 74 R☉ · ≈ 850 ly
Mass16.5–19 M☉ vs 18–24 M☉
Rigel’s luminosity61,500–363,000 × the Sun
Rigel’s age≈ 8 million years
Danger zoneonly within ≈ 160 ly
Two giants side by side, and Rigel’s two possible life stories
Original Astrometrik animation. Left: Betelgeuse and Rigel drawn to scale (radii about 750 and 74 times the Sun). Right: a simplified temperature–luminosity diagram. Rigel may be on its first trip from the main sequence towards the red supergiants (route 1) or already on its way back after a red-supergiant phase (route 2). The bar on Rigel shows the spread of published luminosities.
Rigel: the bigger mystery
Rigel is a blue supergiant about 74 times wider than the Sun, with 18 to 24 solar masses and an age of about 8 million years, roughly 850 light-years away. It is an Alpha Cygni variable: its brightness shifts slightly between magnitude 0.05 and 0.18 as its unstable atmosphere pulsates, with periods from about one day to several weeks.
The puzzle is where it stands in life. Its pulsations match a star that has already been a red supergiant and has turned back towards the blue, shedding a lot of mass on the way. Its surface chemistry, with about twelve times more nitrogen relative to carbon than at birth, fits a star still on its first trip towards the red. Studies (Georgy et al. 2013, Saio et al. 2013) call this contradiction unresolved.
Why Rigel’s power ranges from 61,500 to 363,000 Suns
Published luminosities for Rigel differ by a factor of almost six. Most of that spread comes from distance and method: Hipparcos puts Rigel about 850 light-years away, while Gaia places its companions near 1,010 light-years. Because the light we receive drops with the square of the distance, a star thought to be 20% farther must be about 40% more luminous to look the same.
Why does Rigel look brighter?
Seen from Earth, Rigel usually outshines Betelgeuse even though it is farther away, so it must send out much more visible light: its absolute visual magnitude is about −7.8. In total power, counting infrared and ultraviolet too, the two are closer than they look. Cool Betelgeuse emits most of its energy as infrared, while hot Rigel shines strongly in visible and ultraviolet light; both come out at roughly 100,000 Suns or more.
A quick check with the Stefan–Boltzmann law, which holds for any star: Rigel’s radius of about 74 Suns and temperature of 12,100 K give about 105,000 times the Sun’s power, close to the often quoted 120,000. Rigel’s variability changes its brightness by only about 10%, far too little to explain the spread between estimates; distance and method do that.
So who goes first?
Both stars are burning helium in their cores, the last long phase before the end, but the exact stage cannot be measured from outside. More massive stars live faster, which slightly favours Rigel, while a post-red-supergiant Rigel would be even further along. Betelgeuse’s age estimate also depends on disputed models. Either way, both are far beyond the roughly 160 light-years within which a supernova could harm Earth: whichever explodes would simply give us the brightest star show in recorded history.
Our short animated video compares Orion’s two supernova candidates.
Slide the distance: how luminous must Rigel be?
The farther away Rigel really is, the more light it must emit to look as bright as it does. Slide to compare with the Hipparcos distance of about 850 light-years.
Compare them tonight
In mid-October Orion rises around 22:30–23:00 and is best seen before dawn. Orange Betelgeuse sits at the upper left, blue-white Rigel at the lower right; right now Rigel is clearly the brighter of the two. Our sky map shows where to look from your location.
Nobody knows. Both are supergiants in their helium-burning phase; Rigel is a little more massive, but the exact stage of either star cannot yet be measured.
How big is Rigel compared with Betelgeuse?
Rigel is about 74 times wider than the Sun, Betelgeuse about 750 times, so Betelgeuse is roughly ten times wider. Rigel is much hotter and far brighter in visible light, while in total power both are around 100,000 Suns or more.
Why do Rigel’s luminosity estimates differ so much?
Mainly because its distance is uncertain and different methods are used. Published values range from about 61,500 to 363,000 times the Sun.
Would a Rigel or Betelgeuse supernova be dangerous?
No. A supernova would have to be within about 160 light-years to harm Earth; Betelgeuse is about 550 and Rigel about 850 light-years away.
Sources and calculation
Sources: Wikipedia, “Rigel” (read 16 October 2026; distance, luminosity range, mass, radius, temperature, absolute magnitude, age, variability); Georgy et al. 2013 and Saio et al. 2013 on blue supergiants and Rigel’s pulsations; Moravveji et al. 2012 (asteroseismology of Rigel); Przybilla et al. 2010 (Rigel’s mass and abundances); Joyce et al. 2020, The Astrophysical Journal (Betelgeuse); NASA and NOIRLab/Gemini on Siwarha (2025); EarthSky on supernova safety distance. A viewer’s comment under our Betelgeuse Reel on Instagram prompted this article.
Positions and times were recalculated with Astronomy Engine, the sky-calculation library Astrometrik uses; times for Vienna and Istanbul are local time. The artwork on this page was drawn by Astrometrik.