Astronomers mark the anniversary of Charles Messier discovering the Whirlpool Galaxy

French astronomer Charles Messier first observed the Whirlpool Galaxy, also cataloged as Messier 51 or M51, on Oct. 13, 1773, as reported by Astronomy Magazine and Space. [1][2]

Writing about the object a few months after the initial observation, Messier described it as a very faint nebula without any stars, according to Astronomy Magazine. The deep space target later became the 51st entry in his official catalog of non-cometary objects. [1]

The Whirlpool Galaxy is located 31 million light-years away in the constellation Canes Venatici and measures 76,900 light-years in diameter. It was the first astronomical object to be classified as a spiral galaxy, featuring an active galactic nucleus classified as Seyfert 2. [5]

Although Messier discovered M51 while searching for comets, astronomers did not recognize its true galactic nature until the 20th century. Gravitational interactions with its companion dwarf galaxy, NGC 5195, distorted its structure about 500 million years ago, compressing gas to trigger ongoing bursts of star formation. [6]