before this week's supernova eruption. credit: STScI/AURA
Whirlpool galaxy 31 million light years away.

Newly discovered supernova appears to blink in before and after photos of the Whirlpool galaxy. credit: Stéphane Lamotte Bailey
On May 31st one amateur noticed a new star embedded within one of the
spiral arms of the distant galaxy where there wasn’t any before. By the
next evening other amateur stargazers and robotic supernova patrol
telescopes clued in as well and the alarm was sounded to the worldwide
observing community. Sky and Telescope website is
reporting that professional
astronomers are scouring through images of the Whirlpool from
international observatories including the Hubble space telescope taken
weeks and even years before the supernova became visible to see what the
precursor star might have looked like before it blew up. This will help
us gain critical insight into the inner clockwork of these titanic
event that are ranked as some of the most powerful forces in the
universe.
Called a Type II Supernova, this new discovery is a member of an
elite stellar club of heavyweights -supergiant stars at least 10 times
larger than our sun that completely destroy themselves when they reach
the end of their lives. Astronomers believe that a supernova explosion
occurs about once a century in all spiral galaxies. However this galaxy
appears to be testing that theory since this will be the third such
stellar detonation to occur in the same galaxy in just 17 years!
The Whirlpool lives up to its name as a real showpiece in large
aperture telescopes under dark skies. Known also as M 51, it was first
observed by comet sleuth Charles Messier back in 1773 and was the first
galaxy where a definite spiral structure was seen.

Sky chart showing M 51 is located just off the Big Dipper handle; Credit: YourSky software
While you shouldn’t expect picturesque views of those spiral arms – a
la Hubble – it’s just about visible through suburban binoculars which
will pick up the nucleus as a faint, tiny smudge. Meanwhile hints
of sweeping spiral arms hugging a bright central core can be
glimpsed with medium sized telescopes (6 to 8 inches) under dark sky
conditions. Careful observation also reveals a much smaller and dimmer
companion galaxy that appears to be interacting with one of the
Whirlpool’s spiral arms.
Being relatively bright and within reach of the average telescope
owner - it’s no wonder that the 60,000 light year wide
Whirlpool is a popular ‘must-see’ deep- sky target for stargazers.
Even though detailed views may be challenging, the ’wow’ moment for
observers is simply the fact that this distant object can be glimpsed
with the human eye.
For those in the Northern Hemisphere, its perfectly positioned in the
evening night sky to hunt down this time of the year. You’ll find the
galaxy located just off the handle of the famous Big Dipper pattern of
stars within the constellation Canes Venatici.
What about seeing the supernova? The star is way too faint (14th
magnitude) to be spotted with anything less than a medium to large sized
telescope – at least ones with primary mirrors of 8 to 16 inches. On
the other hand it should be a fairly easy target for backyard digital
astroimagers with the right setup even in light polluted suburbia. But
because this supernova was caught early on, it may still have a surprise
in store and continue to brighten a bit in the next week or so. No
guarantees but the only way to know for sure is for us to keep an eye on
it. i know where I will be pointing my telescope the next clear night!
Andrew Fazekas, aka The Night Sky Guy,
is a science writer, broadcaster, and lecturer who loves to share his
passion for the wonders of the universe through all media. He is a
regular contributor to National Geographic News and is the national
cosmic correspondent for Canada’s Weather Network TV channel, space
columnist for CBC Radio network, and a consultant for the Canadian Space
Agency. As a member of the Royal Astronomical Society of Canada, Andrew
has been observing the heavens from Montreal for over a quarter century
and has never met a clear night sky he didn’t like.