Last updated on April 18, 2014 at 12:48 EDT
M101 Ultraviolet Visible and Near Infrared
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M101 Ultraviolet, Visible, and Near Infrared

April 18, 2005
The image above shows how the same galaxy can appear very different depending on which part of the electromagnetic spectrum you are looking at. The images cover the same area of sky at the position of M101.

The GALEX ultraviolet image highlights the active regions of star formation concentrated in the spiral arms of M101 and shows that star formation is occurring in the outer regions of this galaxy. The visible light image (that can be seen with the human eye) displays the spiral arm structure and the central core of older stars. An image of the near infrared light (just outside the range human eyes can see) from M101 shows the location of the oldest stars concentrated in the core and spread more evenly across the spiral arms.

Astronomers use images at many wavelengths to understand the star formation history of galaxies.