M51, also known as Messier 51a or NGC 5194, is a spiral galaxy in the constellation Canes Venatici. It’s located 31 million light-years from Earth. M51’s arms are made of long lanes of stars, dust, and gas, and appear like a staircase. Sometimes the designation M51 is used to refer to the pair of galaxies, in which case the individual galaxies may be referred to as M51a (NGC 5194) and M51b (NGC 5195).
The Whirlpool Galaxy has two, very prominent spiral arms that wind clockwise. One arm deviates from a constant angle significantly. The pronounced spiral structure of the Whirlpool Galaxy is believed to be the result of the close interaction between it and its companion galaxy NGC 5195.
As a result of the Whirlpool Galaxy’s interaction with NGC 5195, a variety of tidal features have been created. The largest of these features is the so-called Northwest plume, which extends out to 43 kiloparsecs (140,000 light-years) from the galaxy’s center. This plume is uniform in color and likely originated from the Whirlpool Galaxy itself due to having diffuse gas. Adjacent to it are two other plumes that have a slightly bluer color, referred to as the Western plumes due to their location. These plumes are what I was trying to capture and highlight in my image. Very faint trailing dust.
NGC 5195 (also known as Messier 51b or M51b) is a dwarf galaxy that is interacting with the Whirlpool Galaxy (also known as M51a or NGC 5194). Both galaxies are located approximately 31 million light-years away in the constellation Canes Venatici. Together, the two galaxies are one of the most widely studied interacting galaxy pairs.
A plate-solved and annotated version is available on my Astrobin page.
