Betelgeuse (Alpha Orionis), is a red supergiant star located in the constellation Orion, has long captivated scientists and astronomers. This massive star is typically the second-brightest star in Orion and among the ten brightest stars in the sky. Its distinctive reddish glow makes it a familiar sight, but its fascinating nature of variability goes well beyond its color. At 10 million years old, Betelgeuse is much younger than our Sun (4.6 billion years old), which also offers crucial insights into the final stages of massive stars.

If it were to replace our Sun, it would be staggeringly large, extending beyond Jupiter’s orbit and engulfing planets Mercury, Venus, Earth, and Mars within it. Betelgeuse is cooler on its surface, despite being much larger and more luminous than the Sun, and it is also far shorter-lived. This provides evidence of the diversity of stellar evolution pathways.

Studying Betelgeuse is crucial for several reasons; it offers a very remote laboratory of understanding how massive stars die, including the mechanisms behind supernovae (a star explosion which produces and seeds the universe with heavy elements necessary for living organisms); Its stellar variability serves as real-time evidence for stellar behavior which benefits astrophysics and astronomical calibration standards; and its impending fate.

Betelgeuse is expected to undergo a supernova within the next 100,000 years. This event will become a model and inform us about the fate of many massive stars.

The Great Dimming

Image Credit: ESO/J. Drevon et al.

Betelgeuse’s brightness fluctuates over time, making it a semi-regular variable star with a main period of nearly 400 days. In late 2019 and early 2020, Betelgeuse showed an unprecedented drop in brightness known as the “Great Dimming”. It dimmed by a factor of 2.5, making it fall outside the top 20 brightest stars. This also sparks speculation of an imminent supernova.

Research revealed that the dimming was likely caused by an enormous surface mass ejection that produced a dense cloud of dust, which partially obstructed the star’s view from Earth.

Shockwaves and mass loss episodes were evident as driving factors based on High-resolution spectroscopic studies. This provides concrete evidence for the dynamic and turbulent nature of the lives of red supergiants.

In July 2025, an international team of astronomers finally confirmed the existence of

“Betel-Buddy,” a nickname of Betelgeuse’s companion, using the advanced speckle imager ALopeke (Hawaiian for “fox”) with the Gemini North telescope via using short exposures to remove the distortions caused by Earth’s atmosphere. Betel-Buddy is about 1.5-1.6 times more massive than the Sun and six magnitudes fainter than Betelgeuse. A likely young star that has not begun hydrogen fusion. It orbits Betelgeuse’s extended atmosphere, comparable to four times the distance of Earth from the Sun.

Betel-Buddy (left) Betelgeuse (right)

Image Credit:International Gemini Observatory / NOIRLab / NSF / AURA / M. Zamani, NSF’s NOIRLab.

So, what lies ahead for Betelgeuse and its companion? For the next few millennia, it is set to bring dramatic changes. Tidal forces between Betelgeuse and Betel-Buddy will cause the smaller star to spiral inward and will eventually merge with Betelgeuse. Moreover, a fiery supernova is expected of Betelgeuse; this event will scatter heavy elements formed from its core and will shine as bright as a half-moon. No worries, since we have enough distance from this star, it will pose no danger to Earth.

Betelgeuse is not just a bright dot in the sky. It is a dynamic laboratory for studying the evolution of massive stars. Discoveries from the Great Dimming to the revelation of its companion add a new chapter to our understanding of the cosmos. These studies ripple into our daily lives, fueling technologies reliant on astrophysical principles, inspiring the arts and sciences, and reminding us how tiny yet meaningful we are in the universe. Betelgeuse’s story prompts us to ask profound questions about our origins and the fate of stars everywhere.