Closest exo-planet to Earth

The closest confirmed exoplanet to Earth is Proxima Centauri b, a roughly Earth-sized planet that orbits our Sun's nearest celestial neighbour, the red dwarf Proxima Centauri C. The Proxima Centauri system is located 4.2 light years from Earth. The planet was discovered by a team led by Guillem Anglada-Escudé (ESP) and its details were first published on 24 August 2016. Proxima Centauri b's general characteristics have since been confirmed by three further independent, peer-reviewed studies.

Proxima Centauri b is an object of great interest to planetary scientists, due to its relative proximity and its broadly Earth-like characteristics. PC-b has a mass of between 1 and 1.27 times that of Earth, is probably around the same size, and may even have some sort of atmosphere.

It orbits its parent star at a distance of 0.048 astronomical units (twenty times closer than Earth is to the Sun), but because Proxima Centauri is much smaller and cooler than the Sun, the planet sits in the "Habitable Zone" with an estimated equilibrium temperature of 234 K (-39 C; -38 F). For context, Earth's equilibrium temperature is 255 K ((−18 C; −1 F).

The planet is probably tidally locked (meaning that the same face is always pointing towards its sun, like the Moon to Earth), and the surface likely gets bathed in high levels of solar radiation. This would make it a challenging environment for life, but doesn't rule out the possibility.

In 2020 a research team claimed to have found evidence of another planet, tentatively called Proxima Centauri c, in a more distant orbit around the star (which would make it periodically the closest to Earth). However, no follow up observations have seen evidence planet, so its existence remains unconfirmed.