What is Betelgeuse? The Star That Might Explode
TL;DR Summary
Betelgeuse is one of the largest stars visible to the naked eye. Learn about its massive size, its mysterious dimming, and when it might go supernova.
Betelgeuse (Alpha Orionis) is one of the largest stars visible to the naked eye and one of the most studied objects in modern astronomy. Located approximately 700 light-years away in the constellation Orion, it serves as the "right shoulder" of the hunter and blazes with an orange-red hue that stands out dramatically against the winter sky.
How Big Is Betelgeuse?
With a radius roughly 700 times that of our Sun, Betelgeuse is classified as a red supergiant — one of the most massive types of stars in the universe. If placed at the center of our solar system, its surface would extend past the orbit of Jupiter.
This immense size makes it one of the most luminous stars we can observe, shining approximately 126,000 times brighter than our Sun. Despite being 700 light-years away, it ranks as the tenth-brightest star in the night sky.
The Great Dimming of 2019-2020
In late 2019 and early 2020, astronomers observed Betelgeuse dramatically fading in brightness — an event dubbed "The Great Dimming." Its apparent magnitude dropped from its usual ~0.6 to about 1.6, making it noticeably dimmer to the naked eye.
This triggered widespread speculation that Betelgeuse was about to go supernova. However, follow-up studies showed that the dimming was caused by a massive ejection of stellar material that cooled and condensed into dust, temporarily obscuring the star.
When Will Betelgeuse Explode?
While Betelgeuse is in the final stages of its life on astronomical timescales, "final stages" still means tens of thousands to hundreds of thousands of years. Current models suggest it will explode as a Type II supernova sometime in the next 100,000 years — possibly much sooner.
When it does, the supernova will be visible from Earth in daylight for weeks, rivaling or exceeding the full Moon in brightness at night.
Observing Betelgeuse
Betelgeuse is best viewed from November through March in the Northern Hemisphere. Look for the bright reddish star forming the upper-left corner of Orion's distinctive rectangular shape. It's one of the easiest stars to identify due to its distinctive orange-red color.
Use Astroneo to explore an interactive 3D model of Betelgeuse and check tonight's visibility from your location.