Interstellar comet 3I/ATLAS has swung past the sun at about 126 million miles and is now heading out, briefly hidden from Earth behind the sun. Astronomers expect it to reappear in predawn skies for telescope users around November 11, with a safe closest pass to Earth on December 19 at roughly 168 million miles. As only the third known interstellar visitor, it’s under intense scrutiny: SPHEREx and the James Webb telescope detected water, carbon dioxide, carbon monoxide, carbonyl sulphide and ice, and early studies suggest it’s 3–11 billion years old. ESA missions also captured difficult glimpses.