M 51

Whirlpool Galaxy
Messier51 sRGB.jpg
Whirlpool Galaxy (M51A or NGC 5194), the smaller object in the upper right is M51B or NGC 5195
Observation data (J2000 epoch)
Constellation Canes Venatici[1]
Right ascension 13h 29m 52.7s[2]
Declination +47° 11′ 43″[2]
Redshift 0.001544[2]
Distance 31 Mly[3]
Apparent magnitude (V) 8.4[4]
Characteristics
Type SA(s)bc pec[2]
Size 76,000 light-years in diameter
Apparent size (V) 11′.2 × 6′.9[2]
Notable features Interacting with NGC 5195[5]
Other designations
Question Mark Galaxy,[2] Rosse's Galaxy,[2] M51a,[2] NGC 5194,[2] UGC 8493,[2] PGC 47404,[2] VV 001a,[2] VV 403,[2] Arp 85,[2] GC 3572[2]
The Whirlpool Galaxy, also known as Messier 51a, M51a, and NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus.[5][6][7] It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy.[8] Its distance is 31 million light-years away from Earth.[9]

The galaxy and its companion, NGC 5195,[10] are easily observed by amateur astronomers, and the two galaxies may be seen with binoculars.[11] The Whirlpool Galaxy has been extensively observed by professional astronomers, who study it to understand galaxy structure (particularly structure associated with the spiral arms) and galaxy interactions.