In 1845, Lord Rosse observed Messier Object 51 with his telescope—the largest telescope in the world. He was the first to see its spiral shape, which would later give it its name. Astronomers had already speculated that it was an island universe similar to our Milky Way Galaxy, but they wouldn't be proven correct for almost 100 years.
M51 is actially two galaxies. The Whirlpool itself is more formally called NGC 5194, and its smaller companion is NGC 5195. The smaller galaxy is situated behind the larger one now, but it has been orbiting it for some time. The gravity of NGC 5195 is probably what caused the Whirlpool's spiral arms to separate from one another and become so clear.
While it is enormous, the Whirlpool is three times smaller than the Milky Way, and contains less mass as well. It is estimated to be 38,000 light years across, and have 160 billion solar masses. A supernova occurred in the Whirlpool in 2005, fortunately, just after the Hubble Space Telescope had finished doing a massive survey of the galaxy, allowing us to look at an image of the star before and after it exploded. That data allowed us to estimate the distance to the galaxy as 23 million light years—closer than was previously thought.
Back Up to Deep Space |
Finder Chart Regular Size Caption Credit: The sky chart program, Stellarium, available at stellarium.org |
Hubble Image Regular Size Large Size Caption Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) |
Deep Image Regular Size Full Size Caption Credit: Jon Christensen at www.christensenastroimages.com |
Zoom Locations Regular Size Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) |
Zoom 1: Edge of an Arm Regular Size Caption Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) |
Zoom 2: Center Regular Size Caption Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) |
Zoom 3: Dusty Star-Forming Region Regular Size Caption Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) |
Zoom 4: Massive Star Cluster Regular Size Caption Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) |
Supernova Animation Regular Size Caption Credit: NASA, ESA, W. Li and A. Filippenko (University of California, Berkeley), S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) |
Region Surrounding the Black Hole Regular Size Caption Credit: H. Ford (JHU/STScI), the Faint Object Spectrograph IDT, and NASA |
Through a Telescope Regular Size Caption |