Surprise ‘tail’ found on an iconic galaxy may rewrite its history

In the first test image from the Vera C. Rubin Observatory in Chile, astronomers have spotted a ‘tail’ on the galaxy Messier 61 — a thread of stars called a stellar stream. Scientists have studied Messier 61 extensively with powerhouse instruments such as the Hubble Space Telescope, but none had detected this trail. Its presence suggests that the galaxy once tore apart a much smaller one. The power of Rubin, which contains the largest-ever digital camera, leads astronomers to hope that this finding is only an appetizer for observations to come.