M51: The Whirlpool Galaxy in Dust and Stars

Explanation: 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 above image is a digital combination of a ground-based image from the 0.9-meter telescope at Kitt Peak National Observatory and a space-based image from the Hubble Space Telescope highlighting sharp features normally too red to be seen. Anyone with a good pair of binoculars , however, can see this Whirlpool toward the constellation of 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 a smaller galaxy just off the top of this image.