The Sky This Week, 2011 June 14 – 21 — Naval Oceanography Portal
Some 27 million years ago a massive star in an outer spiral arm of a galaxy known as Messier 51 reached the end of its life. Within a matter of minutes the star’s core collapsed onto itself, then rebounded in a cataclysmic explosion known as a supernova. The "flash" of visible light from the dying star, billions of times brighter than the star’s normal light output, enabled Earth-based astronomers to detect the event on May 31, 2011. Supernovae are extremely rare events that occur infrequently in most galaxies. No supernova has been observed within our Milky Way galaxy since the one discovered by Johannes Kepler in 1604. While supernovae are discovered almost daily in very remote galaxies, the opportunity to study one in a nearby galaxy such as M51 comes along only a few times in a decade. Messier 51 is a favorite target of astronomers and may be seen with binoculars or small telescopes from dark locations on a Moonless night. It was nicknamed "The Whirlpool Nebula" by William Parsons, Third Earl of Rosse, who first detected the galaxy’s spiral structure with his 72-inch aperture reflecting telescope at Birr Castle in Ireland in 1845.
The Sky This Week, 2011 June 14 – 21 — Naval Oceanography Portal
When we look up, we look back, even millions of years.