Super Earth discovered where temperature during day is a scorching 725°C

Astronomers used the James Webb Space Telescope to examine the surface of LHS 3844 b, a super-Earth 48.5 light-years away. The findings suggest a hot, basalt-rich world without an atmosphere, widening the picture of rocky exoplanets.

In Short

• Researchers used mid-infrared data to infer the planet's surface composition
• The planet is tidally locked, with permanent daylight and endless darkness
• No atmosphere means heat stays trapped, sharpening the day-night contrast

Astronomers have identified a scorching “super-Earth” beyond our solar system where daytime temperatures soar to an astonishing 725°C, offering a rare glimpse into the extreme diversity of rocky worlds in the universe.

The planet, LHS 3844 b, lies about 48.5 light-years from Earth and is roughly 30% larger than our planet.

Using the powerful James Webb Space Telescope, researchers were able to directly study the planet’s surface composition, an achievement that marks a significant step forward in exoplanet science.

Unlike Earth, LHS 3844 b is tidally locked, meaning one side of the planet permanently faces its host star. This results in a blistering, unending day on one hemisphere, while the other side remains in perpetual darkness.

The dayside reaches temperatures of about 1000 Kelvin (around 725°C), making it one of the hottest rocky exoplanets ever studied.

“This is a dark, hot, barren rock, devoid of any atmosphere,” said Laura Kreidberg, director at the Max Planck Institute for Astronomy and principal investigator of the study. The findings were published in Nature Astronomy.

The absence of an atmosphere is a key feature. Without it, heat is not redistributed around the planet, creating extreme temperature differences between the day and night sides. It also leaves the surface exposed to intense radiation and constant bombardment by space debris.

Scientists used the telescope’s mid-infrared instrument to analyse the planet’s emitted heat. By studying this radiation, they could infer the surface composition. The results suggest a dark, basalt-rich terrain, similar to volcanic rock found on Earth’s mantle or the surfaces of the Moon and Mercury.

Lead researcher Sebastian Zieba explained that the planet likely lacks Earth-like plate tectonics and water, both essential for forming the silicate-rich crust seen on our planet. Instead, its surface may either be geologically inactive and heavily weathered or shaped by ancient volcanic activity.

The discovery highlights how far exoplanet research has come, from merely detecting distant worlds to probing their geological makeup.

With further observations planned, scientists hope to refine their understanding of LHS 3844 b and similar planets.

As astronomers continue to explore the cosmos, worlds like LHS 3844 b are redefining what a planet can be, revealing environments far more extreme than anything found in our solar system.

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