M51: The Whirlpool Galaxy from Hubble.

The Whirlpool Galaxy is a classic spiral galaxy. At only 30 million light years distant and fully 60 thousand light years across, M51 , also known as NGC 5194, is one of the brightest and most picturesque galaxies on the sky. The featured image is a digital combination of images taken in different colors by the Earth-orbiting Hubble Space Telescope , highlighting many sharp features. Anyone with a good pair of binoculars , however, can see this Whirlpool toward the constellation of the Hunting Dogs ( Canes Venatici ). M51 is a spiral galaxy of type Sc and is the dominant member of a whole group of galaxies . Astronomers speculate that M51 's spiral structure is primarily due to its gravitational interaction with the smaller galaxy on the image left.