We have told you about the mysterious objects within our home galaxy Milky Way and we have also told you about the Centaurus A galaxy. Now, our journey to galaxies has brought us to a new destination, the Whirlpool galaxy.
Whirlpool galaxy or M51 is a spiral galaxy located 31 million light-years from Earth in the constellation Canes Venatici. This galaxy has a mass equivalent to 160 billion solar masses and has an estimated diameter of 76,000 light-years. It would take a spaceship traveling at the speed of light 60,000 years to get from one to the other side of the galaxy. According to an estimate, it has 100 billion stars.
Discovered in 1773 by Charles Messier while hunting for objects that could confuse comet hunters as comets, this galaxy was first thought to be Nebulae (the cloud of dust and gas where star formation takes place). Nearly a decade later in 1781, a companion dwarf galaxy M51b was discovered by Pierre Mechain. William Parsons, an Irish astronomer in 1845 was the first who discovered the spiral arms of the galaxy and was called the first “Spiral Nebulae” until the Edwin Hubble was able to observe Cepheid variables (stars that pulsate in predictable ways & are used to measure distances) in some of these “spiral nebulae’s”. This provided evidence that they must be entirely separate galaxies because they were so far away.
What’s more fascinating about this galaxy is its interaction of it with its companion dwarf galaxy M51b, which is slowly merging with M51. The tidal forces from M51b on the spiral arms of the Whirlpool galaxy have triggered star formation in the galaxy.