Main article: Chronology of the Universe before emergence of the planet Earth
The Sloanovsky digital heavenly overview (Sloan Digital Sky Survey, SDSS) is the large-scale project provided in 2020 within which scientists collected data for more than 20 years using the telescope in Apachi-Poynt observatory (New Mexico, the USA). On the basis of collected data astronomers created more and more detailed maps of space. Now they integrated all practices in one huge three-dimensional map covering almost all history of formation of the Universe.
Studying of median history of the Universe 11 billion years long
In the project creation of the card as the fact that the new research fills a huge space in knowledge of expansion of the Universe which disturbed astronomers long ago is not so important. The matter is that astronomers rather well know ancient history of the Universe and the recent history of its expansion, but between these stages there is quite big space — about 11 billion years. Five years scientists of SDSS worked directly on filling of this space.
On the new card the data obtained at different investigation phases are used. So astronomers could plot the objects which are at different distance from Earth. To take the missed 11 billion years, scientists collected data from quasars — bright galaxies with very active supermassive black holes in the center.
On the new card Earth is a point in the center. The green sector — the galaxies, next to Earth (according to the data collected during the first two starts of SDSS). Pink and red circles — the area which is at distance up to 6 billion light years from us (according to observations of big, old red galaxies).
Researchers could use the received card for measurement of speed of expansion of the Universe known as Hubble's constant. Strangely enough, they found out that the current value is about 10% lower, than at calculation of a constant of Hubble by measurement of distances to the next galaxies. Scientists assure that information on the card differs in high accuracy. They were puzzled by mismatch of a constant of Hubble to the value received by them, and it requires further studying. It is not the first time when new researches display other value of a constant of Hubble.
The analysis of the card also showed that about 6 billion years ago expansion of the Universe accelerated. It is well known that the rate of its expansion increases. But the previous researches assumed that it began about 4 billion years ago.
And, at last, thanks to the fact that the research covers such big section of space and time it is capable to give most accurately understanding of what "form" of the Universe. Astrophysicists constantly argue, curved it or flat. And so, the SDSS card — one of proofs of a flat form.
The project will continue the work — the new stage of researches should begin at the end of 2020.