New maps of the "oldest light" in the Universe will be released shortly by the European Space Agency (Esa).

The images were assembled from data acquired by the organisation's 600m-euro (£515m) Planck satellite.

The light carries key information about what happened shortly after the Big Bang, and can be used to work out the age of the cosmos - 13.7 billion years being the current estimate.

The Esa space telescope's maps will be the most detailed yet.

A news conference has been called at the agency's headquarters in Paris.

Scientists expect the images to lead to refinements in their ideas for how the Universe came into being. But they will be hoping also for some surprises that can take their studies in new directions and possibly even towards some new physics.

Cold signal
Planck is the third western satellite to study the so-called Cosmic Microwave Background (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.

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.

Before that time, about 375,000 years into the life of the cosmos, conditions would have been so hot that all the light would have been bounced around and trapped in a fog of ionised matter. The Universe would have been opaque.

The "fossil" light is still evident today. It bathes the Earth in a near-uniform glow which, thanks to the expansion of the Universe, can now be found at microwave frequencies.

Its temperature profile is just 2.7 degrees above absolute zero, but it is possible to detect minute deviations from this signal.

These fluctuations reflect the differences in the density of matter when the light parted company and set out on its journey. The subtle lumpiness, driven by gravity, would have seeded the later development of stars and galaxies.

Greater capability
COBE and WMAP extracted astonishing insights from the radiation. In addition to an age for the Universe, CMB studies have thrown up a refined estimate for the contents of the cosmos (4.6% atomic matter; 24% dark matter; and 71.4% dark energy) and an assessment of its geometry.

Scientists describe the Universe as being "flat", meaning space adheres to Euclidean rules, where straight lines can be extended to infinity and the angles of a triangle will add up to 180 degrees, etc.

Planck has much higher sensitivity and resolution than either COBE or WMAP.

Cosmologists hope this improved capability will allow it to probe the light for evidence of "inflation", the faster than light expansion of the Universe that is postulated to have occurred in the first fractions of a second after the Big Bang.

Inflation has been a popular add-on to Big Bang theory since the 1980s.

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