M51 (NGC 5194), the Whirlpool Galaxy, is a classic spiral galaxy where pink star-forming regions mix with blue light from star clusters between arms that curl with dance-like grace. With a diameter of a staggering 60,000 light-years (a light-year is the distance light travels in one year, about 94.6 trillion km), it is among the brightest and most picturesque galaxies in the sky.
This image, released by the National Aeronautics and Space Administration (NASA) on the 14th (local time), was captured at Lijiang Observatory at the 3,200-meter-high summit of Tiezha Mountain in Yunnan Province, China. Images taken in various colors over 58 hours were digitally combined.
Astronomers suspect M51's spiral structure is due to gravitational interaction with the small galaxy directly above it, NGC 5195. It looks as if the smaller galaxy is tugging on the bigger one's arm. The resulting tidal forces trigger the formation of new stars.
M51's elegantly wound arms resemble a grand spiral staircase spanning the cosmos. In reality, they are long lanes of stars and gas mixed with dust. In M51, these arms play a crucial role. They compress hydrogen gas to create new stars, essentially serving as star factories.
In M51's captivating image, red represents infrared light and hydrogen in massive star-forming regions. Blue originates from hot, young stars, and yellow indicates older stars.
M51, discovered in 1773 by French astronomer Charles Messier, lies in Canes Venatici, 31 million light-years from Earth. With an apparent magnitude of 8.4, the galaxy is easily observable with a small telescope. It is best seen in May.