In the spirit of the season, the interstellar comet 3I/ATLAS is changing color as it leaves the sun behind — shifting from a reddish tint to a faint green glow. That visible change signals the comet is reacting to solar heat and releasing new gases in space, giving scientists fresh clues about what it is made of and how it behaves.

Little Foot is a near-complete Australopithecus skeleton — the most complete ever discovered — from South Africa. Researchers first unveiled the small ancient human in 2017, but precisely where it sits on our family tree has been the subject of scientific debate.

Comet 3I/ATLAS, an interstellar visitor, reaches its closest approach to Earth on Dec 19 at about 167 million miles - visible only with a strong telescope. Newsround speaks to an astrophysicist to find out all about it.

Interstellar comet 3I/ATLAS has once again baffled scientists and astronomers with its increasing brightness and striking green hue as it nears Earth. Comet 3I/ATLAS will reach its closest point to Earth on December 19 and astronomers expect it to shine even more at that time.

Discovered on July 1 by the NASA-funded ATLAS telescope in Chile, 3I/ATLAS is only the third confirmed visitor from another solar system, following 1I/'Oumuamua in 2017 and comet 2I/Borisov in 2019.