Alternate Names

NGC 5194/5195, Whirlpool Galaxy

Type

Supermassive

Location

in the constellation Canes Venatici, beneath the Big Dipper

Finder Chart

Distance

27 million light-years

Mass

1 million times the mass of the Sun

Size

Diameter of 4 million miles (6 million km), about four times the diameter of the Sun.

Discovery Methods

• Detection of an accretion disk

M51

This black-and-white picture from a telescope at Kitt Peak National Observatory, Arizona, shows both galaxies that form M51. The smaller galaxy at top is also cataloged as NGC 5195, while the larger one is known as NGC 5194. They are connected by a "bridge"� of stars pulled out of the two galaxies when they passed close to each other tens of millions of years ago.

A Hubble Space Telescope image of the central region of NGC 5194, the larger of the two galaxies that form M51. A supermassive black hole may lie at the center of the bright ball of stars at the center. The bright red blotches in the spiral arms are regions where new stars are being born.

X marks the spot of the black hole at the center of M51 in this Hubble Space Telescope image. The dark stripes that make the X are lanes of dust, which block the light of the brighter stars and gas behind them. Astronomers believe that the black hole is at the intersection of the X.

An ultraviolet view of M51 from the orbiting GALEX spacecraft. The spiral arms are clearly outlined because they contain many hot, young stars, which produce lots of ultraviolet energy.

What looks like an out-of-focus picture of Christmas lights is really an X-ray image of M51 from the orbiting Chandra X-Ray Observatory. The two galaxies of M51 are filled with clouds of hot gas, which form that reddish background. Individual sources of X-rays -- such as neutron stars and black holes -- show up as points of light. M51's supermassive black hole is in the bright white blob of light at the center.

This document was last modified: November 19, 2009.