The largest rocky planet discovered so far

TOI-849 b is a highly unusual exoplanet known as a "chthonian planet," meaning it is likely the stripped, rocky core of a former gas giant.

Key characteristics

Temperature: It has an estimated surface temperature of approximately 1,530°C (2,780°F). This makes it far hotter than even Venus due to its close proximity to its star.

Density: The planet's mean density is about 5.2 g/cm³, which is comparable to Earth's and Venus's. This high density is what leads scientists to believe it's a solid, rocky core rather than a gas planet.

Size: TOI-849 b has a radius of about 3.4 Earth radii, making it roughly the size of Neptune.

Mass: Despite its Neptune-like size, it is incredibly massive, with nearly 40 times the mass of Earth.

Orbit: The planet orbits its star very closely, completing one full revolution in just 18 hours. This places it within the "Neptune desert," a region where such massive planets are rarely found.

The combination of its Neptune-like size and Earth-like density is highly unusual for a planet of its mass and location. This has led researchers to theorize that the planet was once a much larger gas giant whose outer atmosphere was blasted away by its star's intense radiation