Post by glactus on Nov 16, 2008 4:16:56 GMT
The whirlpool galaxy
The Whirlpool Galaxy, Messier 51a, is an interacting grand-design spiral galaxy located at a distance of approximately 23 million light-years away in the constellation of Canes Venatici. It is one of the most famous spiral galaxies in the sky and was discovered by Charles Messier on October 13, 1773. Its Apparent magnitude is 9.0
The galaxy can be easily observed by amateur astronomers, and may even be seen with binoculars. The Whirlpool Galaxy is also a popular target for professional astronomers, who study it to further understand galaxy structure and galaxy interactions.
M51's bright circular disk has a radius of about ~38,000 light-years. Its mass is estimated to be 160 billion solar masses. Compared to 100,000 light years diameter of the Milky Way, M51 has about half its size and mass.
A black hole, surrounded by a ring of dust, is thought to exist at the heart of the spiral. The dust ring stands almost perpendicular to this relatively flat spiral galaxy.
A secondary ring crosses the primary ring on a different axis, a phenomenon that is contrary to expectations, and a pair of ionization cones extend from the axis of the main dust ring.
Credits: This is a NASA/ESA image
