A false-colour image of the whole sky as seen by Planck. The dust throughout the Galaxy is shown in blue, while hot gas can be seen as red regions across the centre of the image. In the background, the mottled yellow features are relic radiation, called the Cosmic Microwave Background, which contains information about the earliest stages of the Universe. This image is a low-resolution version of the full data set. The areas of sky shown in previous releases are outlines and labelled. Image credit: ESA / LFI and HFI Consortia.
Image credit: ESA / LFI and HFI Consortia
Image credit: ESA / LFI and HFI Consortia
Planck has delivered its first image of the entire sky. By looking at microwave radiation, it not only provides new insight into the way stars and galaxies form, but also tells us how the Universe itself came to life after the Big Bang.
Professor George Efstathiou, at University of Cambridge and the Planck Survey Scientist, said “it has taken sixteen years of hard work by many scientists in Europe, the USA and Canada, to produce this new image of the early Universe. Planck is working brilliantly and we expect to learn a lot about the Big Bang and the creation of our Universe.”
Dr David Parker, Director of Space Science and Exploration for the UK Space Agency, added, “Planck has ‘painted’ us its first spectacular picture of the Universe. This single image captures both our own cosmic backyard – the Milky Way galaxy that we live in – but also the subtle imprint of the Big Bang from which the whole Universe emerged. We’re proud to be supporting this great new discovery machine and look forward to our scientists unravelling the deeper meaning behind the beauty of this first image.”
From the closest portions of the Milky Way to the furthest reaches of space and time, the new all-sky Planck image is an extraordinary treasure chest of new data for astronomers. The main disc of our Galaxy runs across the centre of the image. Immediately striking are the streamers of cold dust reaching above and below the Milky Way. This galactic web is where new stars are being formed, and Planck has found many locations where individual stars are edging toward birth or just beginning their cycle of development.
Less spectacular but perhaps more intriguing is the mottled backdrop at the top and bottom. This is the cosmic microwave background (CMB) radiation. It is the oldest light in the Universe, the remains of the fireball out of which our Universe sprang into existence 13.7 billion years ago.
While the Milky Way shows us what our local neighbourhood looks like now, those microwaves show us what the Universe looked like close to its time of creation, before there were stars or galaxies. The CMB radiation was released as the first atoms were forming, about 400 000 years after the Big Bang, and is at the heart of Planck’s mission to decode what happened in the primordial Universe.
The microwave pattern is the cosmic blueprint from which today’s clusters of galaxies were built. The different colours represent minute differences in the temperature and density of matter across the sky. Through the action of gravity, these small irregularities evolved into denser regions that became the galaxies of today.
The CMB covers the entire sky but most of it is hidden in this image by the Milky Way’s emission, which must be digitally removed from the final data in order to see the microwave background in its entirety. Planck looks at the sky in nine different bands, or colours, of microwave light, which have wavelengths thousands of times that of optical light. These nine different bands, ranging from frequencies of 30 to 850 GHz, are crucial for understanding which parts of the Planck data are from the early Universe, and which are from our own Galaxy. Clive Dickinson, of the University of Manchester, said “Planck has the unique ability to distinguish very cold dust at temperatures of just a few degrees above absolute zero (-273.15oC) from the warmer dust at tens of degrees above absolute zero. These regions of space are likely to be where stars form, and Planck will allow us to study such regions over large regions of sky for the first time.”
A number of UK institutions have been involved in the design and construction of the satellite, and are now working alongside colleagues from around the world to operate the satellite and analyse the data. Dr David Clements, of Imperial College London, said “just looking at the pictures you can tell we're seeing new things about the structure of our galaxy. Once we've done that, and stripped away these foregrounds, then it's on to the Cosmic Microwave Background and the glow of the Big Bang itself!”
The image shown here is constructed from data taken from the first ten months of Planck’s main mission, with observations beginning in August 2009. Planck continues to map the Universe, and by the end of its mission in 2012 it will have imaged the whole sky four times. The first full data release of the CMB is planned for 2012. Before then, a catalogue containing individual objects, both regions in our Galaxy and entire distant galaxies, will be released in January 2011.
Professor Peter Ade, at Cardiff University, has been involved with design, construction and operation of the High Frequency Instrument. He said “at last we can see the realisation of the full potential of Planck, showing in exquisite detail our own Milky Way galaxy superimposed on the relic fireball background. It is a fantastic result for this unique satellite, and demonstrates once again that you can only do pioneering science by using advanced and therefore high risk technologies.”
The Jodrell Bank Centre for Astrophysics at the University of Manchester is involved with the Low Frequency Instrument. Rod Davies, Emeritus Professor at Jodrell, said “it is particularly rewarding for me to see the culmination of a 30-year involvement in Cosmic Microwave Background research beginning with radio telescopes at Jodrell Bank in Cheshire, then under the clear dry skies on the high volcanic slopes of Tenerife and finally with the construction by Jodrell Bank of the radio receivers for Planck’s Low Frequency Instrument.”
