'Hubble paints picture of evolving universe'

Astronomers, using the Hubble Space Telescope, have captured one of the largest panoramic views of star birth in the distant universe, featuring about 15,000 galaxies, about 12,000 of which are forming stars.

Hubble's ultraviolet vision opens a new window on the evolving universe, NASA said in a statement.

The telescope tracked the birth of stars over the last 11 billion years back to the cosmos' busiest star-forming period, which happened about three billion years after the big bang.

Ultraviolet light has been the missing piece to the cosmic puzzle, said researchers, including those from the Space Telescope Science Institute in the US.

Now, combined with infrared and visible-light data from Hubble and other space and ground-based telescopes, astronomers have assembled one of the most comprehensive portraits yet of the universe's evolutionary history, they said.

The image straddles the gap between the very distant galaxies, which can only be viewed in infrared light, and closer galaxies, which can be seen across a broad spectrum.

The light from distant star-forming regions in remote galaxies started out as ultraviolet. However, the expansion of the universe has shifted the light into infrared wavelengths.

By comparing images of star formation in the distant and nearby universe, astronomers glean a better understanding of how nearby galaxies grew from small clumps of hot, young stars long ago.

Because Earth's atmosphere filters most ultraviolet light, Hubble can provide some of the most sensitive space-based ultraviolet observations possible.