Planck saw dust

The Planck Space Observatory, which is designed to look at the Cosmic Microwave Background has built up a map of dust concentrations within 500 light years of us across the sky. The results show a warm disc of dust in the plane of the galaxy and colder, more diffuse stuff surrounding it, much as suspected. The dust has been whipped up into strange shapes through the motion of stars, the galaxies and jets of plasma as well as stellar radiation.

The dust is seen in different forms including molecular clouds and ‘cirrus’ clouds. The gas component of these is invisible to the telescope. There are also clumps where gas has collapsed under gravity. The outer layers absorb most of the incoming heat, allowing the cores to cool down and collapse further to form protostars and then stars. At this point, the radiation from the newly formed stars blasts away the gas and dust, making them visible.

Knowing the concentrations of dust out there is helpful in a number of ways. Redening of light from interaction with dust affects estimates of distance and other astronomical observations. Dust also traces the shape of the galaxy. However important the stuff is, dust is rarely observed closely as telescopes sensitive to radiation from very cool sources is required – such as Planck. In the image below, the brighter bits are tens of degrees Kelvin while the dark bits are around 12 K.

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