Planck Telescope Finds Largest Structures in the Universe

A supercluster of galaxies as it appears in Planck data . Such structures contain hundreds of billions of suns

The Planck space telescope has identified some of the largest structures ever seen in the Universe. These are clusters of galaxies that are gravitationally bound to each other and which measure tens of millions of light-years across. Astronomers say the Planck observatory has made more than 20 detections that are brand new to science. The European Space Agency telescope has also confirmed the existence of a further 169 galaxy clusters. Follow-up studies have hinted at the great scale of these structures.

The clusters, sighted in all directions, range out to about four billion light-years ( one light year equals  5.88 trillion miles )  from Earth. Astronomers are interested in such observations because they say something about the way the Universe is built on the grandest scales - how matter is organised into vast filaments and sheets and separated by great voids.
Not only do the clusters contain colossal quantities of visible matter - stars, gas and dust - but they also retain even larger quantities of invisible, and as yet unidentifiable, "dark matter."

Planck made the discoveries during its on-going survey of the "oldest light" in the cosmos. This relic radiation from the Big Bang 13.7 billion years ago fills the entire sky in the microwave portion of the electromagnetic spectrum. It is referred to famously as the Cosmic Microwave Background, or simply the CMB. Planck's ultra-precise recording of this light should provide remarkable new insights on the age, contents and shape of the Universe.

Scientists hope the telescope's imagery can also prove the theory of "inflation", an idea that the cosmos experienced a turbo-charged, faster-than-light-expansion in its first, fleeting moments.  But to get a clear view of all this information, scientists must first subtract the light emitted by other astrophysical phenomena shining in the same frequencies. Although regarded as "noise" in the context of Planck's main mission, this "rejected" light is still hugely valuable to scientists who study its sources - including those astronomers interested in mapping galaxy clusters. Clusters are surrounded by fantastically hot gas - at many millions of degrees.

There is a list of some 15,000 astrophysical phenomena spied by Planck and which, again, are secondary to its main objective of detailing the CMB. Planck will continue to scan the sky until at least the end of 2011, certainly enough for five-times coverage.
Planck is a flagship mission of Esa. It was launched in May 2009 and sits more than a million km from Earth on its "night side".