The Hubble Space Telescope is giving scientists a look at the oldest galaxies ever seen, dating back 13.3 billion years — providing a glimpse into how the cosmos must have looked right after the Big Bang.
Hubble has uncovered seven never-before-seen primitive galaxies dating back to when the universe was less than four per cent of its current age, NASA scientists said.
These archaeological images from Hubble were gleaned from an intensively studied patch of sky known as the Ultra Deep Field.
A team of astronomers led by Richard Ellis of the California Institute of Technology used Hubble's Wide Field Camera 3 to peer deeper into space than any previous Hubble observation.
Hubble scientists said the most ancient of the seven new galaxies came into being about 13.3 billion years ago — some 380 million years after the Big Bang.
With this newest discovery, scientists nudge a little closer to the origins of the universe.
"Looking at these galaxies allows us to learn many, many things about the universe after the Big Bang — about our origins," said Abraham Loeb, chairman of the Astronomy Department at Harvard University.
"For instance, we discovered that the galaxies then were 1000 times denser than the galaxies today," he said.
"These pictures are like the first ultrasound of an infant. It's the oldest archaeology material on the universe," said Loeb.
He expressed hope that Hubble may be able to plumb the depths of space for even older galaxies, perhaps nearly as old as the universe.
"To find the first galaxies we will have to look further, but there is less light, the galaxies are smaller," said Loeb.
The never-before-seen galaxies are key to interpreting the development of the first stars and the formation of the first galaxies that later evolved into the elliptical galaxies like our own Milky Way that now populate the universe, the space agency said.
One major goal of the program is to determine how rapidly the number of galaxies increases over time in the early universe. This measure is the key evidence for how quickly galaxies build up their constituent stars.
Hubble has transformed the field of astronomy since it was first launched in 1990.
Ellis said Hubble continues to make breakthroughs in space research, thanks to the sheer power and precision of the oft-rehabbed space telescope.
Hubble underwent repair during a shuttle mission in 2010 that left it with a new camera and spectrograph as well as fixed and spruced up scientific instruments.
"For the first time in 23 years we could use Hubble full tilt," Ellis said. "Our study has taken the subject forward in two ways."
"First, we have used Hubble to make longer exposures. The added depth is essential to reliably probe the early period of cosmic history," he said.
"Second, we have used Hubble's available colour filters very effectively to more precisely measure galaxy distances," Ellis added.
First launched in 1990, the telescope was repaired and upgraded in 1993, 1997, 1999, 2002, 2008 and 2010. The final upgrade extended the life of Hubble another five years, through 2015.