The most detailed image of the history of the cosmic background radiation – that is, of the vestiges of the Big Bang – has been obtained thanks to ESA’s Planck space telescope and has just been made public. The new map, based on data collected over fifteen and a half months, is a portrait of the first light of the cosmos , which was recorded in the sky when it was approximately 380,000 years old.
Cosmic microwave radiation (CMB) is a backdrop covering the entire cosmos, responsible for a small part of the “snow” that appears on analog TV screens when tuning to a blank channel. As the universe continues to expand, the CMB signal drifts toward microwave wavelengths, the equivalent of a temperature just 2.7 degrees above absolute zero. The speckled patterns represent small variations in temperature, corresponding to regions that, in the early moments of the universe’s history, had a slightly different density. These regions were the seeds of all the structures we see today: galaxies and stars today.
New recipe of the cosmos
According to the standard cosmological model, these fluctuations appeared immediately after the Big Bang and are what is now mapped to the entire Planck sky, with unprecedented resolution and sensitivity. By analyzing the nature and distribution of the “seeds” in the cosmic background radiation image, we can determine the composition and evolution of the universe from its origins to the present . Among other surprising findings, ESA scientists have identified a fairly obvious asymmetry in the average temperatures of the two hemispheres of the celestial vault, in addition to a much larger cold spot than expected.
To this is added that, if before it was considered that the universe was composed of 4.5% ordinary matter, 22.7% dark matter and that the rest was dark energy, thanks to Planck we know that the proportions are slightly different. Thus, the cosmos would contain 4.9% normal matter, 26.8% dark matter and 68.3% dark energy . The Planck telescope image also offers a new value for the expansion speed of the universe, the Hubble constant: it “stretches” 67.15 kilometers per second per megaparsec . And that implies that the universe should be 13.82 billion years old.
