Hubble captures deepest-ever view of the universe

Astronomers have unveiled a photograph of the deepest-ever view of the universe, providing the first glimpse of distant galaxies that are billions of light-years away.

The photo, called eXtreme Deep Field, or XDF, was assembled by combining 10 years of Hubble Space Telescope images taken of a tiny patch of sky. Repeat observations made over the past decade added up to a total exposure time of 2 million seconds, allowing cameras to record the faint light of galaxies that are 1/10th of a billion the brightness of what the human eye can see.

Before the XDF was revealed Tuesday, the deepest view of space was Hubble's photograph called Ultra Deep Field, which was created using data from 2003 to 2004.

"The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen," said Hubble scientist Garth Illingwoth. "XDF allows us to explore further back in time than ever before."

Thousands of galaxies

The new full-colour XDF image contains about 5,500 galaxies, including some that span back 13.2 billion years. The universe is estimated to be 13.7 billion years old.

The photo, which captures a small area of space in the constellation Fornax, shows galaxies at various stages of their evolution. Most are seen when they were young, small and growing often violentlyas they collided and merged together. The light from those past events is just arriving at Earth now.

Large, fuzzy red spotsgalaxies in their declining yearscan also been seen. These areas are where the formation of new stars has ceased and are the remnants of dramatic collisions between galaxies.

Also visible are spiral galaxies similar in shape to our Milky Way and our neighbour Andromeda.

Before the Hubble telescope was launched into space in 1990, astronomers could only see galaxies that were up to seven billion light-years away, about halfway across the universe.

NASA's planned James Webb Space Telescope, which will use infrared technology, will reach even further into the skies, finding fainter galaxies that existed when the universe was just a few hundred million years old.