At some point tonight, the constellation Orion will appear to have lost its bright red star at its shoulder – and scientists are excited.
A Rare Opportunity to See Betelgeuse
This month, some sky watchers will witness the almost complete disappearance of Betelgeuse, one of the most famous and brightest stars in the sky. After a few seconds – despite scientists’ hopes of the star exploding soon – it will return and shine with the same brightness it had before.
An Exceptional Viewing Opportunity
The disappearance of Betelgeuse will create a rare astronomical moment: an asteroid named Leona will block the star from view through a thin strip of Earth’s surface. Scientists welcome this celestial alignment as an opportunity to observe the changing surface of Betelgeuse with the best clarity yet.
An Opportunity to Seize
“This is a great opportunity that nature is giving us, so we must take advantage of it,” says Miguel Montarges, an astronomer at the Paris Observatory, who has helped coordinate many amateur observers to try to witness the event.
The Asteroid Leona
This opportunity comes thanks to a large asteroid called Leona, which was first discovered by astronomers in 1891. By itself, Leona is just a space rock that crosses the paths of asteroids between Mars and Jupiter. However, at precisely 8:17 PM EST on December 11, Leona will slide directly between Earth and Betelgeuse, the red supergiant star that countless generations of people worldwide have known.
Betelgeuse and Brightness Changes
Betelgeuse is a bright shoulder star in the constellation Orion, located just 650 light-years from Earth. Although its brightness fluctuates regularly, the star caught attention in 2019 when scientists realized it was fading rapidly in what became known as “the great dimming.” Despite hopes that humanity would get a front-row seat to the explosion the star will eventually undergo when it runs out of fuel, Betelgeuse has continued – although its brightness is changing faster than before.
A Unique Viewing Opportunity
Over recent years, scientists have studied Betelgeuse using the Hubble Space Telescope, two ground-based observatories, and even a Japanese airborne satellite. However, Leona’s disappearance may give scientists a truly unique view of the star.
Preparations for Viewing
The preparations included two main tactics. First, scientists had to better understand Leona – which involved fortuitously observing smaller and dimmer stars being obscured by the asteroid. Using this data, scientists can refine calculations of the size, shape, and trajectory of the asteroid that will help them interpret observations of Betelgeuse. Leona may even have a moon, according to Roul Behrend, an astronomer at the Geneva Observatory, who has studied the asteroid. He estimates that there is a 10 percent chance that Leona has a moon, although it is unlikely that any one observer will be able to see the asteroid and the hypothetical moon crossing Betelgeuse.
Observation Locations and Equipment
Second, scientists had to direct skilled sky watchers with high-tech equipment along the path of the disappearance, which extends from Mexico across the tip of Florida, southern Spain, Italy, Greece, and Central Asia. The more geographical coverage on the ground, the more complete the map of Betelgeuse’s surface will be. However, some locations offer better weather and a better chance of getting to another spot along the path in case clouds roll in – factors that play a role in gathering as much data as possible.
Ongoing Preparations
Even last week, preparations were ongoing. A team of scientists was working to engage the European Southern Observatory in Chile, which is outside the path of the disappearance, to study the uninhibited Betelgeuse. Meanwhile, Duberry hoped to arrange ultraviolet observations, which can only be obtained from a satellite and will reveal the massive atmosphere surrounding the visible surface of Betelgeuse. José Luis Ortiz, an astronomer at the Astronomy Science Institute in Andalucía, Spain, was striving to attract a stratospheric balloon that could lift cameras above any threatening clouds.
Importance
Vision
The observations that scientists can gather will provide important insights into the mechanics of giant red stars, which burn through strange fuel as they advance in age. Currently, scientists believe that Betelgeuse fuses helium into carbon; after that, the star must convert carbon into oxygen and silicon, and then iron. Finally, Betelgeuse will run out of fuel and collapse under its own weight, exploding and scattering the vital elements for life into space, leaving behind a dense stellar remnant.
Ultimate Goal
What makes Betelgeuse’s fate interesting is that scientists want to understand how the giant red star will end. But for now, scientists’ models for these stars do not quite work. While they show the turbulent star surface – the mingling of dark and light that scientists hope to witness during the disappearance – they never display the continuous outflow of winds emitted by the star or any sort of dust explosion that scientists believe is responsible for the “great dimming.” This means we are missing something important about these stars, and Montalto hopes that the Lyra interventions will eventually provide vital information regarding the awaited end of Betelgeuse.
Ultimate Goal
“In the end, of course, that is our goal,” he says. “If we know how giant red stars live, we can better predict their deaths.”
Megan Bartels is a science journalist based in New York City. She joined Scientific American as a news reporter in 2023. Previously, she spent over four years as a writer and editor at Space.com, in addition to nearly a year as a science journalist at Newsweek, focusing on space and Earth sciences. Her writing has also appeared in Audubon, Nautilus, Astronomy, Smithsonian, and other publications. She graduated from Georgetown University and earned a master’s degree in journalism from the Science, Health, and Environmental Reporting Program at New York University.
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