|What is this?||An image of the whole sky as observed by Planck|
|Where is it in the sky?||It <em>is</em> the sky!|
|How big is it?||This image shows our own galaxy, and also the very early Universe|
|How far away is it?||The earliest stages of the Universe are seen as they 13.7 billion years ago|
|What do the colours represent?||Red colours are longer wavelengths, while blue colours are shorter wavelengths|
This image is the product of the first 10 months of Planck‘s mission. The main feature visible is our own Galaxy, as a white line across the middle, but this is showing gas and dust between the stars, rather than stars themselves. The blue wispy material is diffuse dust, while the red glow is gas and electrons. Planck’s main objective is to map the Cosmic Microwave Background (CMB), which was emitted in the early Universe. This can be seen in regions where the Galaxy is not emitting strongly, as red and yellow mottled appearance at the top and bottom of the image.
The CMB is actually present over the whole sky, but is swamped by the light from our own Galaxy. Plancks large range of wavelengths measured by its two instruments means it can distinguish the light emitted by the Galaxy from the light from the early Universe.
You can see more download options, with different features annotated here.
You can also view explore this image and compare it to different wavelengths on Chromoscope