Webb Telescope Finds Lava Planet Shielded by Reflective Mineral Clouds

The James Webb Space Telescope has identified a highly reflective atmosphere shielding a scorching lava world 280 light-years from Earth. The exoplanet, known as TOI-561 b, bounces back roughly 74 percent of the starlight that strikes its surface. This brilliant reflectivity rivals that of Venus and defies expectations for a world orbiting so close to its host star.[5][6]

Astronomers previously assumed that any rocky planet enduring such intense stellar radiation would have been stripped of its gaseous envelope billions of years ago. Instead of a dark, scorched ball of bare rock, Webb's instruments revealed a thick atmospheric layer. The findings were published in The Astronomical Journal in late 2026 by an international research team.[1][4]

"Our discovery challenges current theories," said Dr. Anjali Piette, an astrophysicist at the University of Birmingham and co-author of the study. "We would expect a heavily irradiated rocky planet like TOI-561 b to have lost its atmosphere billions of years ago. Instead, the evidence suggests it still has a significant atmosphere today."[4][7]

The host star, TOI-561, is estimated to be 10 billion years old, making it twice the age of our Sun. The planet completes a full orbit in just 10.7 hours. Sitting 35 times closer to its star than Mercury does to the Sun, it receives 4,700 times more stellar energy than Earth.[5]

Tracking a Full Orbit

To understand how the planet survives this onslaught, the research team pointed Webb's NIRSpec instrument at the system for 37 continuous hours. This observation window allowed the telescope to capture nearly four complete orbits. By monitoring the system at infrared wavelengths between 3 and 5 micrometers, the astronomers mapped the planet's changing brightness.[4][5]

"We measured how the planet's brightness and heat changed throughout its orbit," said Professor Lisa Dang, the project lead from the University of Waterloo. "This technique, known as a phase curve, revealed that the planet reflects a significant amount of light from its star, and that heat is being redistributed around the planet."[3][4]

The phase curve provided the first detailed look at the exoplanet's nightside, which permanently faces away from the star due to tidal locking. The data showed that the nightside was not warm enough to account for the missing energy from the relatively cool dayside. The only remaining explanation was that the planet reflects three-quarters of the incoming light.[4][5]

This high reflectivity, known as a Bond albedo of 0.74, requires a highly reflective cloud layer. Computer simulations of the planet's climate suggest that these clouds are composed of vaporized rock. Specifically, the models point to silicate minerals, including silicon dioxide and magnesium silicate, condensing to form a protective mineral sunscreen.[1][5]

A Magma Ocean Engine

The presence of these silicate clouds explains how the dayside avoids absorbing the full brunt of the star's energy. As rock vaporizes from the planet's dayside magma ocean, it rises into the atmosphere and cools. This forms reflective clouds near the boundary between day and night, shielding the molten surface below.[5][6]

Maintaining this atmosphere over 10 billion years requires a constant source of replenishment. The intense stellar wind should continuously blow the atmospheric gases away into deep space. Researchers hypothesize that the global ocean of molten rock acts as a planet-wide volcano, constantly outgassing new material to replace what is lost.[4][7]

The planet's physical dimensions support the theory of a deep, volatile-rich envelope. TOI-561 b measures about 1.4 times the width of Earth but holds 2.2 times its mass. This gives the exoplanet a lower overall density than most rocky worlds found on such tight orbits, hinting at a substantial layer of lighter atmospheric material.[5]

The study, led by Samuel Boucher of the Université de Montréal, marks a significant milestone in exoplanet atmospheric science. Webb has examined several small rocky worlds around red dwarf stars and found them to be bare rock. TOI-561 b, orbiting a larger and older star, represents one of the strongest cases yet of a rocky exoplanet retaining its air.[5]

Redefining Planetary Resilience

The survival of TOI-561 b's atmosphere forces planetary scientists to revise their models of atmospheric loss. Traditional frameworks dictate that extreme ultraviolet and X-ray radiation from a host star will quickly strip away the primordial atmospheres of close-in planets. The mineral sunscreen mechanism provides a newly observed pathway for atmospheric preservation.[1][7]

This discovery also highlights the diverse chemical compositions possible in extreme alien environments. While Earth's clouds are made of water vapor and Venus is shrouded in sulfuric acid, TOI-561 b demonstrates that vaporized rock can drive complex weather systems. The condensation of magnesium silicate creates a highly reflective barrier that fundamentally alters the planet's energy balance.[1][5]

Astronomers are now eager to determine the exact chemical makeup of the invisible gases supporting these clouds. The underlying atmosphere could be a dense blanket of carbon dioxide, similar to a much hotter Venus. Alternatively, it might be rich in sulfur dioxide, resembling the volcanic emissions seen on Jupiter's moon Io.[4]

Isolating the planet's faint signal from the overwhelming glare of its host star required sophisticated data processing. The dayside of TOI-561 b adds only a few dozen parts per million to the total light of the system. The team had to carefully model stellar granulation—the slow boiling pattern on the star's surface—to ensure their measurements were accurate.[5]

Future Webb Observations

The success of the 37-hour continuous observation proves the James Webb Space Telescope's unprecedented capability to characterize extreme worlds. By capturing full-orbit phase curves, researchers can now map temperature distributions and cloud cover on planets that cannot be imaged directly. This technique will be applied to other ultra-short period planets in the coming years.[5][6]

Future studies will likely focus on identifying specific spectroscopic signatures of the silicate clouds. While the current phase curve data strongly supports the presence of silicon dioxide and magnesium silicate, direct detection of their absorption lines would confirm the models. Researchers are already planning follow-up proposals for Webb's next observing cycles.[1][5]

The findings from TOI-561 b also have implications for understanding the early history of our own solar system. During its infancy, Earth may have experienced a magma ocean phase following the giant impact that formed the Moon. Studying lava worlds offers a unique window into the atmospheric dynamics of planets in a molten state.[1][2]

The discovery that the oldest and most irradiated planets can hold onto their atmospheres expands the boundaries of planetary science. If a world receiving 4,700 times Earth's stellar energy can maintain a protective cloud layer, the mechanisms of atmospheric retention are far more robust than previously understood. The universe continues to prove that planets are highly dynamic systems.[4][5]