#messier 91

When Charles Messier was observing and logging deep space objects on the night of March 18, 1781, chances are very good that M91 was what he was describing when he recorded: “Nebula without stars, fainter than M90″. But, there was a problem… Charles Messier made a rare bookkeeping mistake and logged its position wrong. So, for a long time M91 was a missing Messier object, as Messier had determined its position from M89 while he thought it was from M58. M91 was catalogued as H II.120 by William Herschel in 1784. Navigating using the directions that Messier initially, yet erroneously logged, Herschel thought the object to be NGC 4571, a beautiful but faint barred spiral galaxy. The identity of M91 was corrected by observations by astronomer William C. Williams in 1969. Prior opinions have been that M91 had either been a comet which the great comet hunter Messier mistook for a nebula. Measurements done by the Hubble Space Telescope indicate that M91 is moving away from us at a speed of about 400 km/s (895,000 mph). The galaxy’s particular speed is unusual because the Virgo Cluster is moving away from us at a speed of 1100 km/s (2.4 million mph), indicating M91 must be traveling toward us at 700 km/s (1.5 million mph) relative to the other galaxies in the Virgo Cluster. -JMP http://www.universetoday.com/48349/messier-91/ http://messier.seds.org/m/m091.html Image Credit: Kitt Peak National Observatory (Haynes)/NOAO/AURA/NSF

Some of the more prominent galaxies include: the pair known as “the Eyes”, M86 (left eye) and M84 (right eye) along with the “mouth” NGC 4388. The galaxy at bottom center is M87, at bottom left is M89 and M90, and the three brightest at top left (from left to right) are NGC 4571, M91, and M88.