Alternate Names

NGC 3031

Type

Supermassive

Location

in the constellation Ursa Major

Finder Chart

Distance

12 million light-years (3.9 megaparsecs)

Mass

7 million times the mass of the Sun

Size

Diameter roughly 30 million miles (45 million km), about 30 times the diameter of the Sun.

Discovery Methods

• Measuring the motions of gas

M81

A beautiful view of M81 shows its spiral arms and its bright nucleus.

An ultraviolet view of M81 from Europe’s orbiting XMM-Newton X-ray telescope. The bright dot in the center represents the hot accretion disk that encircles the central black hole.

An ultraviolet view from the orbiting Galaxy Evolution Explorer (Galex) satellite.

This view of M81, obtained by a telescope aboard a space shuttle mission, shows the galaxy in both visible (red and yellow) and ultraviolet (blue) wavelengths. The blue regions are much hotter than the others, and outline the galaxy’s spiral arms and its nucleus. The nucleus may contain a supermassive black hole.

This document was last modified: November 19, 2009.