An astrophotograph of the interstellar comet known as 3I/ATLAS highlights its green coma and a wandering blue-tinted ion tail. (Copyright Victor Sabet and Julien De ...

The question sounds ripped straight from a sci-fi blockbuster like Arrival or 2001: A Space Odyssey, yet it became a very real source of furious, months-long online debate. The cosmic object at the ...