Astronomy can be viewed as a good Sherlock Holmes story or perhaps an episode of CSI. Because no one was there at the beginning of the Universe 13.8 billion years ago, or for many billion of years afterward, scientists try to re-create events based on the available evidence. This means studying planets, asteroids, cosmic dust, stars, nebulae, black holes, supernovae and other objects, phenomena, light and radiation.

One important piece of evidence used is Cosmic Microwave Background (CMB). CMB is ‘fossil’ light left over from a time only 380 thousand years after the Big Bang, when the Universe was hot and dense. As the Universe expanded, that light spread out and now covers the whole sky at microwave wavelengths.

From 2009 until 2013, researchers used the European Space Agency (ESA) Planck satellite to study and map this background radiation. Minute differences in the temperature of the CMB reflect differences in density in the early cosmos, providing insight into the shape of the current Universe.

What they have found indicates that the first stars came to live 100 million years later than previously thought.

Following the Big Bang, protons, electrons and neutrinos existed in a hot, dense cloud. Because everything was tightly packed together, photons and electrons collided so frequently that light could not travel any significant distance before crashing into something else.

This hot, dark period is known as the “reionisation” epoch. As the cosmos expanded and became cooler these collisions became less frequent allowing protons and electrons could combine to form neutral atoms and photons could escape the cloud.

Parts of this data have been published in a variety of scientific journals since 2013. The results have largely confirmed the current cosmological picture of the Universe.

“But there is more: the CMB carries additional clues about our cosmic history that are encoded in its ‘polarisation’. Planck has measured this signal for the first time at high resolution over the entire sky, producing the unique maps released today,” said Jan Tauber, ESA’s Planck project scientist in a statement.

The end of “reionisation” and the birth of the first stars is usually pegged at about 440 million years after the big bang. The new results show that the first stars were about 100 million years younger than that.

“According to Planck’s observations, stars may be younger than believed, in bearing with other independent astrophysical indicators, and this finding may have major consequences on our attempts to understand the dark components of the universe,” Senior scientist Dr Carlo Baccigalupi, from the International School of Advanced Studies in Trieste, Italy told the Guardian.

As with any good mystery story, knowing when events occurred is a crucial starting point for filling in other key details.

The latest results are explained in detail in the journal Astronomy and Astrophysics.

Additional information about the Planck data are available on the ESA’s Planck website, or the US Planck Mission website at CalTech. Further data from the CMB survey is expected to be released in March, 2015.

The Planck satellite, named for Nobel Prize winning German physicist Max Planck was officially switched off on October 23, 2013.