U.S. astronomers detected the most distant galaxies whose light rays traversed space for 13 billion years and are just now reaching Earth, it was announced Tuesday.

These are traces of the most distant galaxies ever detected, according to astronomers at Caltech university in California.

Looking through the 10-meter Keck Two telescope, located on top of Mauna Kea on the Big Island of Hawaii, a Caltech-led team of international scientists used "gravitational lensing" to find evidence of the distant galaxies.

The technique is used to help astronomers detect distant galaxies, the light from which often bends as it passes through gravitational fields of massive objects while traveling through space, officials said. The scientists used massive clusters of galaxies in the "gravitational lensing" technique to find systems that would not be detected by looking through a traditional telescope.

"By looking through carefully selected clusters, we have located six star-forming galaxies seen at unprecedented distances, corresponding to a time when the universe was only 500 million years old, or less than four percent of its present age," said Caltech astronomer Richard Ellis, leader of the team.

Scientists said the cosmic findings are important in the continuing search for "cosmic dawn," which is the term scientists used to refer to the moment when the universe went from complete darkness to the very first shining stars and galaxies.

"We estimate the combined radiation output of this population could be sufficient to break apart the hydrogen atoms in space at that time, thereby ending the Dark Ages," said Caltech graduate student Dan Stark, who used three years of observations from the study for his thesis.

The "Dark Ages" refers to a period when no stars were shining, starting when the universe was just 500,000 years old, officials said.

Pinpointing exactly when the "Dark Ages" ended was the motivation for the cosmic survey and is the impetus for building even more powerful telescopes in the future, according to Caltech astronomers.

Ellis will present the findings on Wednesday to a Geological Society conference in London.