Betelgeuse: how big and far it is, and when it will explode

Betelgeuse is the orange-red star at Orion's shoulder: a red supergiant so big that, in place of the Sun, its surface would reach beyond the orbit of Mars. One day it will explode as a supernova, but NASA says that is not likely for about another 100,000 years. You can see it with your own eyes on winter evenings. The quick facts:

What is Betelgeuse?

Betelgeuse is a red supergiant: a huge, cool star in a late stage of its life. NASA says it is about 15 times more massive than the Sun and about 7,500 to 14,000 times brighter. Its surface is cooler than the Sun's, about 3,300 degrees Celsius against the Sun's roughly 5,500, which is why it looks orange-red.

It is also young. At roughly 10 million years old, according to NASA, it is much younger than our nearly 5-billion-year-old Sun. How can a young star already be near its end? NASA explains that because Betelgeuse is much more massive, it burns through its fuel much faster, so it lives a much shorter life.

In 1995 the Hubble Space Telescope took the first direct picture of the surface of a star other than the Sun, and that star was Betelgeuse. The ultraviolet image, released in 1996, shows a huge atmosphere with a hot spot.

How to find Betelgeuse

1. On a winter evening, face southeast (later in the night: south). 2. Find Orion's Belt: three bright stars close together in a short, straight line. Our Orion guide explains this step in detail. 3. Look up and to the left of the belt, about 9.8 degrees away (our calculation). The bright orange star there is Betelgeuse. The blue-white star on the other side of the belt is Rigel. 4. To check, find the Winter Triangle: Betelgeuse, Procyon and Sirius, the brightest star of the night sky, form a big triangle with sides of about 26 to 27 degrees (our calculation).

The colour is the easiest clue: Betelgeuse looks clearly orange, while Rigel and Sirius look blue-white. (Aldebaran, higher up, is orange too, but it is outside Orion.) The real sky has no lines; the picture in the FAQ shows the same view in Stellarium with the lines switched off. You can also check the sky for your own location with Stellarium Web.

When can you see Betelgeuse?

The main evening season is autumn to spring. In November it rises in the evening, in January and February it is high in the south around 9 or 10 p.m., and by May it sets soon after the Sun. From about May 8 to July 31, 2027, Betelgeuse does not meet our observing test from New York: at least 10 degrees above the horizon while the Sun is more than 12 degrees below it (our calculation). It is closest to the Sun in our sky around June 19. After that summer gap it returns in the early morning sky before dawn, and by autumn it is back in the evening.

Betelgeuse from New York, for the night that begins on each date (local clock time; heights in degrees above the horizon, where 0° is the horizon and 90° is straight overhead; our calculation):

At its highest, Betelgeuse is about 57 degrees up from New York. In spring its highest point falls in daylight, so look in the evening, before it sets. Because it sits close to the celestial equator, it can be seen from almost everywhere on Earth, in the Southern Hemisphere too.

How big is Betelgeuse?

Enormous. A 2020 study by Meridith Joyce and colleagues found a radius of about 764 times the Sun's, with a range of about 702 to 880 times. Turned into distances (our conversion), that is about 3.55 times the distance from Earth to the Sun, between 3.26 and 4.09 times. Placed where the Sun is, Betelgeuse would swallow Mercury, Venus, Earth and Mars, and its surface would end well short of Jupiter, which orbits about 5.2 times farther from the Sun than Earth (NASA fact sheet). See our article on how far the Sun is from Earth for that basic distance.

By volume, about 446 million Suns would fit inside a star of that radius (our calculation).

NASA's explainer gives a rounder picture: about 700 times the size of the Sun, stretching past Jupiter's orbit. NASA's Hubble page explains part of the difference: the star's thin outer atmosphere, seen in ultraviolet light, would extend past Jupiter's orbit. A star like this has no sharp edge, so the size depends on what you measure.

How far away is Betelgeuse?

Several hundred light-years, but astronomers do not fully agree. The four published estimates below have central values between about 427 and 724 light-years, each with its own uncertainty. A light-year is the distance light travels in one year. Different methods give different answers: some use the tiny yearly shift in the star's position as Earth goes around the Sun (parallax), others use models of how the star works.

Four published estimates (our conversion to light-years):

NASA's explainer rounds it to about 700 light-years. Whatever the exact number, the light you see tonight left Betelgeuse centuries ago: with the 2020 estimate, around the year 1478 (our calculation).

What was the Great Dimming?

In late 2019 Betelgeuse suddenly faded. NASA says that within months it had dimmed by about 60%, and by April 2020 it was back to normal. People wondered if it was about to explode.

It was not. Images from ESO's Very Large Telescope show the star's southern part getting darker during the dimming. ESO and NASA explain what happened: the star threw a large bubble of gas from its surface out into space; when it cooled, the gas turned into dust that blocked some of the star's light. What exactly set off the huge ejection is still not known.

Betelgeuse also has a small companion. In July 2025 NASA announced that a team led by Steve Howell had spotted a very faint companion star with the Gemini North telescope in Hawai'i. Its proposed name is Siwarha, meaning "her bracelet". In January 2026 NASA reported that Hubble and two ground-based observatories had found a wake of gas that the companion leaves in Betelgeuse's outer atmosphere; it crosses in front of the star about every six years, or about 2,100 days. NASA predicts the companion will next be at its widest separation from Betelgeuse in November 2027, giving big professional telescopes another chance to image it. You cannot see the companion yourself.

When will Betelgeuse explode?

There is no known date. Betelgeuse will end its life as a supernova, a huge explosion of a dying star, but NASA says that "isn't likely to happen for about another 100,000 years". The 2020 study by Joyce and colleagues places the star in the stage where it burns helium in its core.

So the Great Dimming was not a sign of the end. Betelgeuse is not expected to go supernova within a human lifetime, although its brightness will keep changing.

What would the Betelgeuse supernova look like from Earth?

A very bright point of light in Orion. Simulations by Jared Goldberg and Evan Bauer at the University of California, Santa Barbara, reported by Astronomy magazine in 2020, found that the supernova would shine about as bright as the half Moon for more than three months, according to the magazine. It would be visible in daylight for about a year and to the naked eye at night for several years before it fades.

Our brightness chart puts that in perspective. In astronomy, a smaller magnitude means a brighter object. As an example, the first-quarter (half) Moon of November 2026 is about magnitude -10.1 (Astronomy Engine): roughly 3,000 times as bright as Sirius and roughly 16,000 times as bright as Betelgeuse's catalogue value in SIMBAD (our calculation).

Would it be dangerous? No. NASA says a supernova would have to be less than 50 light-years away to damage Earth's ozone layer. With the four distance estimates above, Betelgeuse is roughly 9 to 14 times farther away than that (our calculation).

Betelgeuse FAQ

Is Betelgeuse in the Orion constellation? Yes. It marks Orion's shoulder, up and to the left of Orion's Belt as seen from the US on winter evenings.

How much bigger is Betelgeuse than the Sun? Its radius, the distance from its centre to its surface, is about 764 times the Sun's radius, according to a 2020 study; NASA rounds it to about 700 times the size of the Sun. In place of the Sun, its surface would reach past Mars.

How many Suns can fit inside Betelgeuse? About 446 million, by volume, using the 2020 radius (our calculation).

Has Betelgeuse already gone supernova? We cannot be completely sure, because its light takes centuries to reach us: we see it as it was hundreds of years ago. But scientists expect about another 100,000 years before it explodes, so the chance that it already happened in the last few centuries is very small (our reasoning from NASA's estimate).

How many years does Betelgeuse have left? There is no known explosion date. NASA says it is not expected for roughly another 100,000 years.

How long would the supernova be visible? In the 2020 simulation, about as bright as the half Moon for more than three months, visible in daylight for about a year, and visible at night for several years.

Which is brighter, Sirius or Betelgeuse? Sirius. It is magnitude -1.46 against Betelgeuse's 0.42 (SIMBAD), so Sirius looks about 6 times brighter (our calculation).

Why does Betelgeuse flicker? Like other stars, it twinkles because its light passes through moving air, most of all when it is low in the sky. That twinkling is separate from the star's own, slower brightness changes. These include a pulsation of about 400 days (NASA) and a cycle of about 2,100 days, roughly six years, that NASA's 2026 report links to the companion star.

Is Betelgeuse older than our Sun? No. NASA gives Betelgeuse an age of roughly 10 million years, against nearly 5 billion years for the Sun.

Would a Betelgeuse supernova harm Earth? No. NASA says a supernova would have to be within 50 light-years to damage the ozone layer; Betelgeuse is hundreds of light-years away.

What does the name Betelgeuse mean? Writing in Saudi Aramco World in 2010, Robert W. Lebling explains that experts trace the name to the Arabic yad al-jawza', "the hand of the giant", the giant being Orion. A copying mistake between two similar-looking Arabic letters later turned it into the form we use today.

How do you pronounce Betelgeuse? BAY-tel-jooz, according to NASA's Night Sky Network.

Another winter target: the Big Dipper and the North Star.

How we checked

Star positions and brightness (V magnitudes) and Betelgeuse's parallaxes come from the SIMBAD database (CDS, Strasbourg), queried on 1 November 2026 through its official Harvard mirror because the main server did not respond. The other distance estimates and the radius come from the published papers by Harper et al. (2017) and Joyce et al. (2020); we converted parsecs to light-years (1 parsec ≈ 3.26156 light-years) and solar radii to distances from the Sun. Rise times, heights from New York, the nights when Betelgeuse misses our New York observing test (checked every ten minutes) and the brightness of the Moon and Venus are our calculations with the Astronomy Engine library; we checked the sky of 15 December 2026 in Stellarium, which gave the same heights for five stars to within 0.01°. Facts and images come from NASA and ESO, listed under Sources. We checked all sources on 1 November 2026.

The brightness chart and the size animation show values from the sources and our own conversions; we did not run our own supernova simulation. None of the images or videos is AI-generated.