Galaxy 101

The Hubble Space Telescope captures the most detailed image ever taken of a spiral galaxy.

Astronomers stitched together 51 separate images from Hubble – with a few other details from ground-based instruments – to build this mosaic of Messier 101, also known as the Pinwheel Galaxy. At an impressive 16,000 by 12,000 pixels, the image is the largest and most detailed ever caught of a spiral galaxy.

The Pinwheel Galaxy is about 170,000 light-years wide, almost twice the diameter of our own Milky Way, and is estimated to contain at least one trillion stars. Astronomers believe that perhaps 100 billion of those stars may be similar to our Sun, and millions of individual objects can be picked from this image.

The galaxy itself sits about 25 million light-years away toward the northern constellation Ursa Major. The light that reached Earth to build this portrait left the Pinwheel Galaxy during our planet’s Miocene Period, when the first mastodon appeared and mammals were flourishing.

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