The Planck Space Telescope put out its first full sky map yesterday. The map, which can be seen at their website with various annotations, shows three major features. The first is a slender near white glow, the intense, relative to other mapped sources, glow of the centre of the Milky Way. Around it are blue tendrils of cold dust. Behind that lies the redder mottled surface of the Cosmic Microwave Background, or CMB.
Planck maps the sky in microwaves and nearby radiation, covering a wider range of channels than previous CMB mapping missions. The reason for this is to look at the black body radiation of the three signals. The Sun, which is pretty hot, radiates energy peaking in visible light. It radiates less energy in nearby wavelengths and even less energy in wavelengths further from the peak. Planets, which are warm, have peak radiation in the infrared, and also radiate less energy overall. Dust, which is cold, radiates in longer wavelengths – far infrared, microwaves and submillimetre radiation. The CMB, as its name suggests, peaks in the microwaves at a different temperature to the dust.
As their relative intensity changes at different wavelengths (the CMB will be brightest in microwaves, dust will achieve maximum brightness at longer wavelengths then dim again and the Milky Way will be brighter the longer you go) image analysis software looking at the nine selected wavelengths of Planck will be able to separate out the three components and produce a more refined version of the CMB than has previously been obtainable. Furthermore, the sky will be mapped four times in total (at least), allowing the images to be added together, producing a more sensitive map.
This first look through Planck’s eyes has been heavily reported. Press releases include ESA and Jodrell Bank, news reports include the BBC and Astronomy Now and blog reports include Skymania and the Astronomy Blog.