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Charles Messier initially began sketching and cataloging anything that was not a comet using a four-inch refracting telescope, adopting the Latin word for “cloud,” which he used to classify his objects as either a star cluster or “nebula.” He documented Messier 51 in 1773 as one of these first 110 objects. William Parsons again observed M51 in 1845 with a 72-inch reflecting telescope, resolving what he dubbed the first spiral nebula. His 1845 drawing clearly defines what we now know to be a spiral galaxy, however it was not until the 1920s that Edwin Hubble, using the 100-inch Hooker telescope at Mount Wilson Observatory in Los Angeles, proved that our Milky Way was just one of an untold number of galaxies spinning through the cosmos.
Modern astronomers now use the relationship of M51 and neighboring NGC 5195 to study how galaxies interact. Due to its near-constant observation, three recent supernovae have been observed in M51, in 1994, 2011, and 2019. Just in September 2020 a potential exoplanet was detected in M51 using the eclipsing-transit method for observing distant stars. If confirmed, this would be the first planet discovered outside our galaxy. By way of comparison, all the current exoplanetary candidates in the Milky Way galaxy are within a radial distance of no more than 25,000 light-years. The candidate in the Whirlpool Galaxy is 31 million light-years distant.
Today many amateur astronomers enjoy M51 or the Whirlpool Galaxy as a good place to learn how to hop from star to star in search of other objects in the sky. The basic spiral structure of the galaxy can be seen with a good pair of binoculars or small telescope, and is relatively easy to find through much of the year. Start at the Big Dipper, locating the last two stars in the handle. Moving southwest 3.5 degrees at a near right angle, the Whirlpool Galaxy and its companion galaxy are unmistakable, first as an elongated fuzzy gray ball, then resolving in greater detail with larger scopes.
If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub.org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk, or event.
Adam England is the owner of Manzanita Financial and moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/insuredbyadam.
