Astronomy Picture of the Day

Explanation: It was the strongest gravitational wave signal yet measured -- what did it show? GW250114 was detected by both arms of the Laser Interferometer Gravitational-wave Observatory (LIGO) in Washington and Louisiana USA earlier this year. Analysis showed that the event was created when two black holes, each of mass about 33 times the mass of the Sun, coalesced into one larger black hole with a mass of about 63 solar masses. Even though the event happened about a billion light years away, the signal was so strong that the spin of all black holes was accurately deduced for the first time. Furthermore, it was confirmed better than before, as previously predicted, that the total event horizon area of the combined black hole was greater than those of the merging black holes. Featured, an artist's illustration depicts an imaginative and conceptual view from near one of the black holes before collision.