Hubble sees "first light" galaxies after the Big Bang theory for about one billion years ago.

The universe was a vast dark space before light traveled across it. The theory is that the cosmos was covered in a thick fog of hydrogen gas that kept the light trapped and began to clear by the process called "reionization," which let the light escape in all directions and turned the universe crystal clear, according to Space Daily on Oct. 23, Friday.

The scientific community has thought reionization as a mystery. Neutrons and protons had combined into electrically charged atoms of helium and hydrogen, in which the ions began to attract electrons and converted into electronically neutral atoms that create a thick fog that contained the light.

The Hubble Space Telescope captured the data in a lengthy sky survey, Astronomy Magazine has noted. Astronomers said that they have generated the most accurate statistical description of early galaxies, which existed in the universe about 500 million years after the Big Bang that people learn today.

Therefore, the astronomers have "looked back in time" as they discovered more than 250 of the earliest dwarf galaxies. The formation of the first galaxies as well as the first stars brought a lot of important changes in the quickly evolving universe, the First Galaxies said.

The scientists have studied pictures of three galaxy clusters, which are a part of the three-year Hubble Frontier Fields program that explores the very and most distant space regions via gravitational lensing effects around six different galaxy clusters. Here, the galaxies the team discovered formed about 600 million years after the Big Bang. Hence, this makes them the first galaxy that Hubble has observed for this cosmic epoch.

The research highlights Frontier Fields program's impressive possibilities, in which they currently worked with another three galaxy clusters' images. Presently, the great interest in understanding the first galaxies' properties is important as these play a key role in the process.