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.

A United Launch Alliance Atlas V rocket sent 27 Amazon Leo internet satellites to low Earth orbit from Florida early Tuesday morning (Dec. 16).

Harvard physicist Avi Loeb raises concerns as interstellar object 3I/ATLAS makes its closest pass to Earth later this month.