TRAPPIST-1d

TRAPPIST-1d is located approximately 40 light-years away from Earth in the constellation of Aquarius. It orbits an ultracool red dwarf star named TRAPPIST-1. Despite the distance, it is relatively close to our solar system in astronomical terms.

TRAPPIST-1d resides within the habitable zone of its star, meaning it theoretically has the right temperature to support liquid water. However, its actual habitability is highly debated, as intense ultraviolet radiation from its host star might have stripped away its atmosphere. Current telescope technology cannot yet confirm if it holds an atmosphere or water.

TRAPPIST-1d was discovered using the transit method, which observes the slight dimming of a star's light as a planet passes in front of it. The initial discovery was made by the TRAPPIST (Transiting Planets and Planetesimals Small Telescope) telescope located in Chile. The system's discovery was officially announced by NASA in 2017.

A year on TRAPPIST-1d is incredibly short, lasting only about 4 Earth days. This is because the planet orbits extremely close to its host star. Its tight orbit is what allows astronomers to detect it so frequently using transit observations.