Level 1 — Absolute Beginner

Betelgeuse is a very big star. It is in the sky, in a group of stars called Orion. Betelgeuse is a supergiant. This means it is much, much bigger than our sun.

In 2019 and 2020, Betelgeuse got dim. People were surprised. Later, scientists learned why. The star pushed out a big cloud of dust. The dust blocked some light.

Now, astronomers used a big telescope in Chile. It is called ALMA. They looked at the surface of Betelgeuse. They found hot spots. The hot spots are not new. They have been there for seven years.

Scientists think a small star near Betelgeuse may cause the hot spots. One day, Betelgeuse will explode. But that will not happen soon. It could take thousands of years.

star

A giant ball of hot, glowing gas in space.

supergiant

A star that is extremely large, much bigger than the sun.

telescope

A tool that helps people see faraway things in space.

astronomer

A scientist who studies stars, planets, and space.

hot spot

A small area that is hotter than the area around it.

dust cloud

A group of tiny bits of matter floating together in space.

companion star

A second, smaller star that orbits close to a bigger star.

explode

To burst suddenly with great force.

Level 2 — Elementary

Betelgeuse is one of the biggest and most famous stars that astronomers study. It is a red supergiant located in the constellation Orion, and it sits close enough to Earth that scientists can study its surface in unusual detail.

Betelgeuse became famous in late 2019 and early 2020 when it suddenly grew much dimmer than usual. At first, nobody knew why. Scientists later worked out that the star had thrown off a giant cloud of dust, and that cloud blocked some of the starlight from reaching Earth.

A team of astronomers, led by Bill Dent at the University of Manchester, recently used ALMA, a powerful radio telescope array in Chile, to look closely at Betelgeuse's inner atmosphere for the first time since the dimming event. They discovered that the atmosphere is uneven, with an average temperature of about 2,300 Kelvin and at least two hotter regions, forming glowing hot spots shaped by huge movements inside the star.

What surprised the astronomers most was that these hot spots are not new or temporary. When they compared their new pictures to older ALMA data from 2015, they found the same hot spot in almost the same place, meaning it has lasted for at least seven years, far longer than scientists expected such features to survive.

supergiant

An extremely large and bright type of star, much bigger than the sun.

constellation

A group of stars that forms a recognizable pattern in the night sky.

radio telescope

A telescope that detects radio waves from space instead of visible light.

atmosphere

The layer of gas surrounding a star or planet.

asymmetric

Not evenly balanced or shaped the same on all sides.

companion star

A smaller star that orbits closely around a larger star.

persistent

Continuing to exist for a long time without stopping.

supernova

A powerful explosion that happens when certain large stars reach the end of their lives.

Level 3 — Intermediate

Betelgeuse, the red supergiant marking the shoulder of the constellation Orion, ranks among the closest and most intensively studied giant stars to Earth. Its scale and proximity make it a natural laboratory for scientists trying to understand how massive stars behave as they approach the ends of their lives.

The star drew worldwide attention in late 2019 and early 2020 when it dimmed dramatically and unexpectedly, sparking speculation that it might be nearing a supernova explosion. Researchers eventually determined that the dimming was caused by a giant dust cloud the star had ejected, which temporarily obscured part of its light rather than signaling an imminent collapse.

A team led by Bill Dent at the University of Manchester has now used the Atacama Large Millimeter Array, or ALMA, a radio telescope array in Chile, to examine Betelgeuse's inner atmosphere in detail for the first time since that event. The observations revealed an asymmetric atmosphere with an average temperature near 2,300 Kelvin, punctuated by at least two markedly hotter regions to the northeast and southwest of the star's visible disk, forming irregular hot spots shaped by enormous convective motions churning within the star.

The most striking finding was persistence. When the team compared their recent observations with ALMA data gathered in 2015, the same northeastern hot spot reappeared in nearly the same location with comparable intensity, indicating the feature has endured for at least seven years, a duration current models of convection struggle to explain. Astronomers now suspect that a much smaller companion star, for which strong evidence emerged in July 2026, may be influencing the direction and pattern of these hot spots, offering a new thread to pull on as researchers work out how Betelgeuse will evolve on its way toward an eventual, though likely still distant, supernova.

supergiant

A star of enormous size and luminosity, vastly larger than the sun.

asymmetric

Lacking symmetry, with parts that differ notably from one another.

convective

Relating to the movement of heat through the rising and sinking of hot material.

radio telescope array

A network of linked antennas that observe radio wavelengths from space to build detailed images.

persistent

Lasting or continuing over an unusually long period without fading away.

companion star

A secondary star gravitationally bound to and orbiting near a larger star.

supernova

The violent explosion marking the death of certain massive stars.

obscured

Hidden or made difficult to see, often by something blocking the view.

Level 4 — Advanced

Few stars have been scrutinized as closely, or for as long, as Betelgeuse, the red supergiant that anchors Orion's shoulder. Its combination of immense scale and relative proximity has made it a touchstone for astronomers seeking to understand the turbulent final act of a massive star's evolution, and a new study built on that legacy is challenging assumptions about how stable, or unstable, a dying giant's surface actually is.

The star's most recent brush with global attention came in late 2019 and early 2020, when an unforeseen and precipitous dimming fueled speculation that Betelgeuse might be approaching core collapse. That episode was later attributed to a substantial dust cloud the star had expelled, a phenomenon that temporarily veiled its light rather than heralding an imminent supernova, but it left astronomers eager to examine the star's inner workings more closely once conditions allowed.

A team led by Bill Dent of the University of Manchester has now done precisely that, deploying the Atacama Large Millimeter Array, ALMA, a radio telescope array sited in Chile, to resolve Betelgeuse's inner atmosphere in unprecedented detail for the first time since the dimming episode. The resulting maps depict a markedly asymmetric atmosphere, averaging roughly 2,300 Kelvin, punctuated by at least two conspicuously hotter regions to the northeast and southwest of the visible stellar disk, irregular hot spots evidently sculpted by vast convective currents churning beneath the surface.

What distinguishes this finding from a routine snapshot of stellar turbulence is durability. Cross-referenced against ALMA observations from 2015, the northeastern hot spot recurs in almost the identical position and at comparable intensity, implying a persistence of at least seven years, considerably longer than prevailing convective models would predict for such a feature. Astronomers now propose that a diminutive companion star, for which corroborating evidence surfaced in July 2026, may be orchestrating the orientation and structure of these hot spots, a hypothesis published in Astronomy & Astrophysics in 2026 and covered by outlets including Sci.News, phys.org, and the ALMA Observatory in early September. The eventual supernova that awaits Betelgeuse remains, by every current estimate, millennia away, yet studies like this one sharpen scientists' understanding of the convective processes that will govern the star's final stretch.

supergiant

A star at the extreme upper end of size and luminosity, dwarfing ordinary stars such as the sun.

asymmetric

Characterized by an uneven or irregular structure lacking balanced symmetry.

convective

Pertaining to the circulation of heated material rising and cooler material sinking within a fluid or gas.

radio telescope array

A coordinated network of antennas that combine signals to observe faint radio emissions with high resolution.