Scientists have made an exciting discovery about a rocky planet beyond our solar system. Using NASA’s James Webb Space Telescope, researchers found that TOI-561 b, a super-Earth about twice the size of Earth, actually has an atmosphere. This is surprising because it orbits very close to its star and was expected to be a barren rock.
The study, published in The Astrophysical Journal Letters, challenges long-held beliefs about how planetary atmospheres can survive extreme conditions. Traditionally, scientists assumed that small, hot planets would lose their atmospheres early on, especially if they were under intense radiation. But TOI-561 b seems to defy this rule.
Located just one-fortieth the distance from its star as Mercury is from our Sun, TOI-561 b has high surface temperatures—around 3,200 degrees Fahrenheit (1,800 degrees Celsius)—which would normally suggest it lacks an atmosphere. Yet, the telescope measurements indicate otherwise. So how is this possible?
According to Nicole Wallack, a researcher involved in the study, “Astronomers would have predicted that a planet like this is too small and hot to retain its own atmosphere for long after formation.” However, the temperature readings suggest heat is being spread evenly across the planet, a sign that it possesses a significant atmosphere.
The research team led by Johanna Teske found TOI-561 b’s density is lower than expected for a planet of its size, indicating it might be surrounded by a thick layer of gases. Tim Lichtenberg, another team member, explained that gases are escaping from the planet’s molten interior, creating a balance between the magma ocean and its atmosphere. “This planet must be much more volatile-rich than Earth,” he noted, comparing it to a “wet lava ball.”
Anjali Piette, a co-author of the study, added that strong winds may help distribute heat from the bright day side to the cooler night side of the planet. They also suggested that thick, reflective clouds could keep the atmosphere cooler. The researchers tested various atmospheric compositions and found that only those rich in volatiles matched their observations, ruling out the idea of a thin atmosphere or bare rock.
This discovery could change our understanding of the “cosmic shoreline,” a term used to describe the boundary between planets that maintain atmospheres and those that do not. Traditionally, planets like TOI-561 b, with such high radiation, were believed to be stripped of any gas. As Teske pointed out, this planet’s unique environment might provide clues on how volatile materials remain locked inside during a planet’s formation.
Data from over 37 hours of observations have revealed much, but there’s still more to analyze. Earth and Planets Laboratory Director Michael Walter hinted, “There are more exciting results on the horizon.” For now, TOI-561 b serves as a reminder that the universe holds many surprises, challenging what we thought we knew about rocky worlds.
