The Pinwheel Galaxy: M101 in Ursa Major | Hubble, Spitzer & Chandra Telescopes
This image of the spiral galaxy Messier 101 is a composite of views from the Spitzer Space Telescope, Hubble Space Telescope, and Chandra X-ray Observatory. Each wavelength region shows aspects of celestial objects and often reveals new objects that could not otherwise be studied. The red color shows Spitzer's view in infrared light. It highlights the heat emitted by dust lanes in the galaxy where stars can form. The yellow color is Hubble's view in visible light. Most of this light comes from stars, and they trace the same spiral structure as the dust lanes. The blue color shows Chandra's view in X-ray light. Sources of X-rays include million-degree gas, exploded stars, and material colliding around black holes. Such composite images allow astronomers to see how features seen in one wavelength match up with those seen in another wavelength. It is like seeing with a camera, night vision goggles, and X-ray vision all at once.
The giant spiral disk of stars, dust, and gas is 170,000 light-years across—nearly twice the diameter of our galaxy, the Milky Way. Astronomers estimate that M101 contains at least one trillion stars. The galaxy’s spiral arms are sprinkled with large regions of star-forming nebulas. These nebulas are areas of intense star formation within giant molecular hydrogen clouds. Brilliant, young clusters of hot, blue, newborn stars trace out the spiral arms.
Pierre Méchain, one of Charles Messier’s colleagues, discovered the Pinwheel galaxy in 1781. Located 25 million light-years away from Earth in the constellation Ursa Major, M101 has an apparent magnitude of 7.9. It can be spotted through a small telescope and is most easily observed during June.
Release Date: Feb. 10, 2009
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