page_title: Messier 91
section_title: Features
hierarchical_section_title: Messier 91 / Features
caption_attribution_description: English: Map of M91
context_page_description: Messier 91 is a barred spiral galaxy located in the Coma Berenices constellation and is part of the Virgo Cluster of galaxies. M91 is about 63 million light-years away from the Earth. It was the last of a group of eight nebulae discovered by Charles Messier in 1781.
  Originally M91 was a missing Messier object in the catalogue as the result of a bookkeeping mistake by Messier. It was not until 1969 that amateur astronomer William C. Williams realized that M91 was NGC 4548, which was documented by William Herschel in 1784
context_section_description: The inclusion of Messier 91 in the Virgo Cluster of Galaxies was confirmed in 1997 by a calculation of its distance as 52 +/- 6 million light years from observing Cepheid variables.
  M91's bar is very conspicuous where it lies at an angle of 65/245 degrees when being measured from the North direction to the East.
  There is a considerable peculiar velocity toward us through the Virgo cluster of about 700 km/s while the cluster's recession velocity is about 1100 km/s, this gives an observed recessional velocity of only about 400 km/s. Another source gives its RV as 803 km/s.
  Messier 91 is also classified as an anemic galaxy -i.e., a spiral galaxy with low star formation and content of gas compared with other galaxies of its type-.
caption: M91 map
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