Long description
The image shows two images of the Andromeda galaxy, captured at different wavelengths.
The left-hand image shows the galaxy in visible light. This shows the bright, white bulge of the galaxy, and the surrounding blue disc. Dark dust lanes from the spiral arms wrap around the galaxy’s core. Satellite galaxies and foreground stars are also visible. A label reads ‘visible’.
In the infrared counterpart to this (on the right-hand side), the bulge, the satellite galaxies and the foreground stars are almost entirely invisible. Instead, the emission is concentrated in the spiral arms. The dust, which was dark in the optical view, shines in the infrared. A label reads ‘infrared’.