LHS 3844 b is one of the few rocky planets beyond the solar system whose surface astronomers have begun to read directly. NASA's Transiting Exoplanet Survey Satellite (TESS) found it, and the discovery was published in 2019 in a paper led by Roland Vanderspek. The planet is slightly larger than Earth and whips around a small, cool red dwarf star about 49 light-years away in roughly 11 hours.
In 2019, a team led by Laura Kreidberg used NASA's Spitzer Space Telescope to track how the planet's infrared glow changed as it orbited, a measurement called a phase curve. The side facing the star reached about 1,040 K, while the night side was consistent with zero, so almost no heat was being carried around the planet. That ruled out a thick atmosphere with more than ten times Earth's surface air pressure. The best fit was bare, dark rock that reflects little light.
In 2026, Sebastian Zieba and Kreidberg's team used the MIRI instrument on the James Webb Space Telescope to take the planet's mid-infrared spectrum, published in Nature Astronomy. It best matched a dark surface of basalt, a common volcanic rock, or mantle rock rich in magnesium and iron. A silica-rich crust like Earth's granite continents did not fit, which the team said suggests the planet lacks plate tectonics and water. No sulfur dioxide was seen, so there is no sign of recent volcanic activity.
Also in 2026, two independent teams measured the planet's mass from the wobble it causes in its star. One, led by E. Nagel and using the CRIRES+ and ESPRESSO instruments, found 2.37 Earth masses. The other, led by Alejandro Hacker with ESPRESSO, found 2.27. Both concluded the planet is mostly rock with an Earth-like makeup, and the Hacker team found room for only trace amounts of water.
What remains open is the surface's history. Two pictures fit the Webb data equally well: fresh basalt, or an old surface darkened over time by radiation and meteorite impacts. The team leans toward the second, a long-quiet world like Mercury or the Moon. TerraForge's model agrees that it is a hot, barren rocky planet with almost no chance of habitability. Its single modelled temperature of about 648 K, though, is a planet-wide estimate that cannot show the real contrast between a roughly 1,040 K dayside and a frozen night side.