News in Science

Hubble spies galaxies from baby universe

Baby universe Astronomers have found seven galaxies that formed relatively soon after the universe's birth some 13.7 billion years ago, describing them "as baby pictures of the universe".

One of the objects may be the oldest galaxy yet found, dating back to a time when the universe was just 380 million years old, a fraction of its current age.

"These early galaxies represent the building blocks of present-day galaxies," says John Grunsfeld, NASA's associate administrator for science.

The research, which has been accepted for publication in the journal Astrophysical Journal Letters, appears the pre-press website arXiv.org.

The discovery of galaxies dating back to the universe's early years should help scientists figure out what happened after the 'dark ages', a period of time about 200 million years after the Big Bang explosion when cooling clouds of hydrogen, clumped together by gravity, began to ignite, triggering the first generation of stars.

"It was a very important moment in cosmic history," says astronomer Richard Ellis, with the California Institute of Technology in Pasadena.

Previously scientists did not know exactly when this "cosmic dawn" occurred and whether it was a single, dramatic event that caused all the galaxies to form their first stars, or whether it happened more gradually over millions of years.

This latest find supports theories that the cosmic dawn was a drawn-out affair, with galaxies slowly building up their stars and chemical elements over time, says Brant Robertson of the University of Arizona in Tucson.

Study co-author Anton Koekemoer says the Hubble telescope has been stretched to its limit in detecting these galaxies.

"We could potentially see further galaxies up to the 350 million year mark, but the cameras on Hubble can't detect anything further than this," says Koekemoer, who is a research astronomer with the Space Telescope Science Institute and was in charge of the observations.

He says the James Webb Space Telescope, due to be launched in 2018, will provide more detail about the galaxies in this region and beyond.

"Hubble is giving us the tip of iceberg as far as galaxies from this era. We know that there must be more of these and we expect to be able to detect more with James Webb."