Recent research in Chile has made a breakthrough in the study of the early universe: ground-based telescopes recorded traces of polarized microwave radiation, which interacts with the first stars, which arose about a billion years after the Big Bang. This is a signal from the period, known as "Cosmic Dawn".
CLASS tool (Cosmology Large Angular Scale Surveyor), set in the highland region of Atakami, managed to identify the polarization of microwave radiation, which arises as a result of the scattering of photons on electrons — a side effect of the ionization of neutral hydrogen by the first generation of stars. This is a testament to that, that Earth telescopes, under the conditions of sufficient sensitivity and adequate protection against atmospheric noise, can compete with observations from space.
Scientists confirmed the results, comparing CLASS data with data from the Planck and WMAP missions. They were able to single out a weak one, but the valuable signal of polarized light against the background of microwave radiation is a real reflection of the era of the first stars.