If you haven't yet seen the "new star" in one of our favorite galaxies, M51 in Ursa Major, I encourage you to do so on the next clear night. The supernova erupted in the Whirlpool Galaxy on May 31 and was first observed by French amateur astronomer Amédée Riou. A German astronomer, Thomas Griga, confirmed the observation the next day and soon thereafter the supernova, the third in M51 in the past 17 years, was widely known among astronomers.
Photo Credit: R. Jay GaBany
The supernova, designated SN 2011dh, currently glows at about 14th magnitude, making a reasonably sized amateur instrument - a scope in the 10- to 12-inch range - necessary to see it. Imaging the supernova can be done with a much smaller telescope, of course.
Photo Credit: Anthony Ayiomamatis
The galaxy lies about 26 million light-years away, meaning the star actually exploded roughly 26 million years ago and that we are just seeing the flash of light now. It's a relatively rare event in such a bright and well-known galaxy, and I encourage you to check it out.
I am posting two spectacular photos of the galaxy and the new supernova: a color shot that is quite breathtaking, and a reference image in black and white that shows the supernova's position. Enjoy!