BRUSSELS - An international team of astronomers announced they've discovered the oldest galaxy that formed 13.55 billion years ago, giving scientists a glimpse of the Dark Age of the Universe.

According to a press release from the European Space Agency Tuesday, the team spotted the ancient galaxy after using a combination of the Advanced Camera for surveys aboard NASA's Hubble Space Telescope and the W.M. Keck Observatory in Hawaii.

Johan Richard, the lead author of the new study said: "We have discovered a distant galaxy that began forming stars just 200 million years after the Big Bang."

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"This challenges theories of how soon galaxies formed and evolved in the first years of the Universe. It could even help solve the mystery of how the hydrogen fog that filled the early Universe was cleared," said Richard, also an astronomer of the University of Lyon in France.

The discovery, to be published in the Monthly Notices of the Royal Astronomical Society, may help scientists explain how the Universe became transparent and bright in the first billion years after the Big Bang.

In the Dark Age, almost the first billion years of the cosmos, a diffuse fog of neutral hydrogen gas blocked light in the Universe.

"It seems probable that there are in fact far more galaxies out there in the early Universe than we previously estimated -- it' s just that many galaxies are older and fainter, like the one we have just discovered,"  said co-author Jean-Paul Kneib, scientist at Marseille's Laboratory of Astrophysics in France.