The Whirlpool Galaxy is a familiar one to stargazers and among the many close galaxy neighbours to our own Milky Way. Because of its shape, it was the first galaxy to be classified as a spiral by astronomers. Today, it interests astronomers due to its spiral structure and the interaction it appears to be having with its near neighbour, M51b.
Facts about the Whirlpool Galaxy
- The Whirlpool Galaxy was first discovered in 1773 by Charles Messier, who was charting the skies looking for objects that might be confused with comets.
- In 1845, astronomer William Parsons observed the galaxy pair with his telescope at Birr Castle, Ireland, and found the spiral structure of the Whirlpool.
- The Whirlpool and its companion, M51b have already passed by or through each other once as they dance through a cosmic merger. The smaller galaxy has been severely disrupted by the encounter, and the Whirlpool’s spiral arms are distorted.
- The Whirlpool Galaxy is undergoing huge bursts of starbirth due to its ongoing encounter with its smaller companion galaxy.
- The whirlpool, like many other galaxies, has a supermassive black hole at its heart, surrounded by rings of dust. The core of the galaxy is quite quite active — making the Whirlpool what astronomers call a “Seyfert galaxy”.
- The Whirlpool’s companion, called M51b, is a dwarf galaxy. Because it is being torn apart by the ongoing interaction, it cannot be easily classified. Its current appearance makes it look like an irregular galaxy.
- A bridge of gas and dust ties the two galaxies together as they merge.