Planck and Herschel: The Sky at Two Scales


Local Dust from Planck and IRAS

The image is a three-colour combination constructed from Planck and IRAS satellite imagery. This combination visualises dust temperature very effectively: red corresponds to temperatures as cold as 10° above absolute zero, and white to those of a few tens of degrees. Overall, the image shows local dust structures within 500 light-years of the Sun.

Credit: ESA and the HFI Consortium, IRAS

 Planck and Herschel, a pair of ESA satellites, have begun returning vibrant new images of the Milky Way Galaxy. The satellite duo is scanning the sky at infrared wavelengths that have not been well-studied in the past. Working in tandem, they will help astronomers explore the forces that have shaped our galaxy and the Universe from its early moments. Planck sweeps the entire sky to collect information on the coldest—and oldest—areas of the Universe. When astronomers have identified areas of particular interest using Planck, they use Herschel to hone in to get a detailed look at slightly different wavelengths.

The ESA recently released some of Planck's images that focus on our own galaxy. The above example, which was compiled with data from Planck and another infrared-detecting satellite, IRAS, captures tendrils of cold dust in a section of the Milky Way. Dark patches represent cooler clumps of matter. The brighter areas are much warmer mixtures of gas and dust, which is where stars are likely to form.

Both Planck and Herschel will continue to study the sky's coldest regions in the coming years, and together they will give astronomers an idea of how the Galaxy as we know it was formed.