Planck satellite: Maps detail Universe's ancient light

A map tracing the "oldest light" in the sky has been produced by Europe's Planck Surveyor satellite. Its pattern confirms the Big Bang theory for the origin of the Universe but subtle, unexpected details will require scientists to adjust some of their ideas.

Map of the oldest light in the Universe.

The map shows tiny deviations from the average background temperature, where blue is slightly cooler and red is slightly warmer. The cold spots are where matter was more concentrated and later collapsed under gravity to form stars and galaxies. Image: ESA/Planck Collaboration


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A spectacular new map of the "oldest light" in the sky has just been released by the European Space Agency.

Scientists say its mottled pattern is an exquisite confirmation of our Big-Bang model for the origin and evolution of the Universe.

But there are features in the picture, they add, that are unexpected and will require ideas to be refined.

The map was assembled from 15 months' worth of data acquired by the 600m-euro (£515m) Planck space telescope.

It details what is known as the cosmic microwave background, or CMB - a faint glow of long wavelength radiation that pervades all of space.

Its precise configuration, visible in the new Planck data, is suggestive of a cosmos that is slightly older than previously thought - one that came into existence 13.82 billion years ago.

This is an increase of about 50 million years on earlier calculations.

The map's pattern also indicates a subtle adjustment is needed to the Universe's inventory of contents.

It seems there is slightly more matter out there (31.7%) and slightly less "dark energy" (68.3%), the mysterious component thought to be driving the cosmos apart at an accelerating rate.

"I would imagine for [most people] it might look like a dirty rugby ball or a piece of modern art," said Cambridge University's George Efstathiou, presenting the new picture here at Esa headquarters in Paris.

"But I can assure you there are cosmologists who would have hacked our computers or maybe even given up their children to get hold of this map, we're so excited by it."

Planck is the third western satellite to study the CMB. The two previous efforts - COBE and WMAP - were led by the US space agency (Nasa). The Soviets also had an experiment in space in the 1980s that they called Relikt-1.

How Planck's view hints at new physics

Planck anomalies graphic
  • The CMB's temperature fluctuations are put through a number of statistical analyses
  • Deviations can be studied as a function of their size on the sky - their angular scale
  • When compared to best-fit Big Bang models, some anomalies are evident
  • One shows the fluctuations on the biggest scales to be weaker than expected
  • Theorists will need to adjust their ideas to account for these features

The CMB is the light that was finally allowed to spread out across space once the Universe had cooled sufficiently to permit the formation of hydrogen atoms - about 380,000 years into the life of the cosmos.

It still bathes the Earth in a near-uniform glow at microwave frequencies, and has a temperature profile that is just 2.7 degrees above absolute zero.

But it is possible to detect minute deviations in this signal, and these fluctuations - seen as mottling in the map - are understood to reflect the differences in the density of matter when the light parted company and set out on its journey all those years ago.

The fluctuations can be thought of as the seeds for all the structure that later developed in the cosmos - all the stars and galaxies.

Scientists subject the temperature deviations to a range of statistical analyses, which can then be matched against theoretical expectations.

This allows them to rule in some models to explain the origin and evolution of the cosmos, while ruling out a host of others.

The team that has done this for Planck's data says the map is an elegant fit for the standard model of cosmology - the idea that the Universe started in a hot, dense state in an incredibly small space, and then expanded and cooled.

At a fundamental level, it also supports an "add-on" to this Big Bang theory known as inflation, which postulates that in the very first moments of its existence the Universe opened up in an exponential manner - faster than light itself.

But because Planck's map is so much more detailed than anything previously obtained, it is also possible to see some anomalies in it.

Temperature anomalies in Planck data Planck has confirmed the north/south differences and a "cold spot" in the data

One is the finding that the temperature fluctuations, when viewed across the biggest scales, do not match those predicted by the standard model. Their signal is a bit weaker than expected.

Planck's new numbers

  • 4.9% normal matter - atoms, the stuff from which we are all made
  • 26.8% dark matter - the unseen material holding galaxies together
  • 68.3% dark energy - the mysterious component accelerating cosmic expansion
  • The number for dark energy is lower than previously estimated
  • The new age - 13.82 billion years - results from a slower expansion
  • This is described by a value known as the Hubble Constant
  • It too is revised to 67.15 km per second, per megaparsec (3.2 million light-years)

There appears also to be an asymmetry in the average temperatures across the sky; the southern hemisphere is slightly warmer than the north.

A third anomaly is a cold spot in the map, centred on the constellation Eridanus, which is much bigger than would be predicted.

These features have been hinted at before by Planck's most recent predecessor - Nasa's WMAP satellite - but are now seen with greater clarity and their significance cemented.

A consequence will be the binning of many ideas for how inflation propagated, as the process was first introduced in the 1980s as a way to iron out such phenomena.

The fact that these delicate features are real will force theorists to finesse their inflationary solutions and possibly even lead them to some novel physics on the way.

"Inflation doesn't predict that it should leave behind any kind of history or remnant, and yet that's what we see," Planck project scientist Dr Jan Tauber told BBC News.

CMB - The 'oldest light' in the Universe

Detail of CMB data
  • Theory says 380,000 years after the Big Bang, matter and light "decoupled"
  • Matter went on to form stars and galaxies; the light spread out and cooled
  • The light - the CMB - now washes over the Earth at microwave frequencies
  • Tiny deviations from this average glow appear as mottling in the map (above)
  • These fluctuations reflect density differences in the early distribution of matter
  • Their pattern betrays the age, shape and contents of the Universe, and more and follow me on Twitter: @BBCAmos


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  • rate this

    Comment number 191.

    This kind of research is inspirational, and instils a sense of wonder in the nature of the universe.
    The thought that we can look so far back in time, right to the beginning of the universe in this detail is awe inspiring.
    Much more impressive than the pale religious cop out of "god made it". That just diminishes the wonder and spectacular nature of the natural universe.

  • rate this

    Comment number 190.

    This research has come a long way since the first CMB was released back in 1996, and is still as fascinating. The Big Bang theory is well established, but it is research and observational experiments like this that continues to refine and understand the details and implications of the big bang itself. Well done to all of those involved in this project.

  • rate this

    Comment number 189.

    165. Dan
    I really don't see how a 68% error can be described as slight but at least the map still supports the big bang theory, it needs all the support it can get these days.

    68.3% compared to 71.4% is not a 68% error.

  • rate this

    Comment number 188.

    Anyone know what happened before the big bang?

    All that matter and energy must have come from somewhere.

  • rate this

    Comment number 187.

    Is Sheldon Cooper aware of this?

  • rate this

    Comment number 186.

    The great physicist Walther Nernst didn’t accept the Big Bang theory and in 1937 calculated the background temperature within the galaxy in a Steady State universe as 2.8K. In 1938 he calculated the temperature outside galaxies as 0.75K. In an effort to lend support to their theory, only this latter figure (which we couldn't measure) is widely quoted by Big Bang supporters.

  • rate this

    Comment number 185.

    I love that even the Universe has a North/South divide.

    I wonder if the cold spot represents London? :P

  • rate this

    Comment number 184.

    Beofer this data we were just stabing in the dark about what started this all. Hopefully this will shed some new light on it and theories will be forthcoming. It's daft to expect instant answers to this stuff because unlike religion, a scientific 'fact' -and theories for that matter too- only remains until it is disproven.

  • rate this

    Comment number 183.

    @139 Tony Fisher: Steinhart and Turok's ekpyrotic cosmology includes a Big Bang. It swaps the "inflation" period after the Big Bang for a contraction phase prior to the Big Bang, but keeps a Big Bang. Perhaps you meant that these results do not prove the inflationary period of the Big Bang?

  • rate this

    Comment number 182.

    @105: Light doesnt slow down because of gravity, it is merely deflected, it's velocity remains constant. Lights actual speed is ALWAYS constant, even through a medium, it is just that in a medium it is often hitting things, being absorbed, and then re-emitted due to the new energy given to the atom that absorbed it, and that takes some amount of time.

  • rate this

    Comment number 181.

    A salutary reminder of what our age will be remembered for when our current ‘times of trouble’ are no more than a footnote in history. And also an excellent example of what Europeans can do well together, we should all be proud of the science and engineering teams that have made this possible, tax payer money well spent in my view for once.

  • rate this

    Comment number 180.

    What went bang. why did it go bang, and where did it come from? Science has to answer these questions, or where's the sense of a big bang theory?

  • rate this

    Comment number 179.

    This amazing work tells a lot more than we knew before about the origin and development of the Universe. Some critics say it does not answer all the questions and we shouldn't have spent money on it. I say there is still a lot more work to be done. It is a sign of a civilised society that we are willing to invest substantial resources to find out as much as we can about the Universe we live in.

  • rate this

    Comment number 178.

    @124 Guy "The explanations so far assume that you also know the frequency when it started out, and judge the age from the red shift."

    The thing is we do know the frequency when it started out. Look up spectroscopy (especially spectral lines). There is a lot of information in the light we receive from space and we can use this to measure red shift

  • rate this

    Comment number 177.

    "ALL you non-believers will pay the price eventually"

    So: religion is better, because it punishes people?

    "science is equivalent to the devil, distracting you from the faith"

    Says you, typing on a computer, connected to the internet, no doubt happy to use scientifically derived medicines.

    If science is distracting and evil, shouldn't you be living in a mud hut? Aren't you being a hypocrite?

  • rate this

    Comment number 176.

    @Captain Lort "the weak will follow science like sheep, but the strong will remain and stick by their faith and will be rewarded in the after-life!"

    The same science that allows you to post a comment here with your computer I assume. I applaud you (slow hand clap)

    Its much easier to believe in God than even try to understand the science of the universe.

  • rate this

    Comment number 175.

    Did he find it at the end of a tunnel?

  • rate this

    Comment number 174.

    This picture clearly proves the theory that the universe was laid by the great Brown-headed Cowbird:

    Brown-headed Cowbirds being brood parasites, it will be interesting to know what happened to the parallel universes pushed out of the nest to make room for ours.

  • rate this

    Comment number 173.

    @Andrew West: Not quite. Light has no mass which means gravity does not influence it. Rather gravity distorts space time which light can run into much like if I dig a channel to a body of water and then pour water down the channel, the water would flow down into the body of water. Light acts like this.

  • rate this

    Comment number 172.

    oh the irony of saying "science is the devil" on a machine that works using quantum processes that would never have been developed without science. I'm sure all the medical science you use is the devil too. One thing worse than a fool is a hypocritical one.


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