Washington: Hundreds of billions of solar systems like ours -- comprising planets, asteroids and comets -- may be residing in our Milky Way galaxy, which itself may be like a drop in the ocean of galaxies, feel scientists.
The rarest and largest of galaxy groupings, called galaxy clusters, can be the hardest to find.
That`s where the National Aeronautics and Space Administration`s (NASA) Wide-field Infrared Survey Explorer (WISE) can help.
The mission`s all-sky infrared maps have revealed one distant galaxy cluster and are expected to uncover thousands more.
These massive structures are collections of up to thousands of galaxies bound together by gravity. They were born out of seeds of matter formed in the very early universe, and grew rapidly by a process called inflation, the Astrophysical Journal reports.
"One of the key questions in cosmology is how did the first bumps and wiggles in the distribution of matter in our universe rapidly evolve into the massive structures of galaxies we see today," said Anthony Gonzalez of University of Florida, Gainesville, who led the research programme, according to a NASA statement.
"By uncovering the most massive of galaxy clusters billions of light years away with WISE, we can test theories of the universe`s early inflation period," added Gonzalez.
WISE completed its all-sky survey in 2011, after surveying the entire sky twice at infrared wavelengths.
The 16-inch telescope ran out of its coolant as expected in 2010, but went on to complete the second sky scan using two of its four infrared channels, which still functioned without coolant.
At that time, the goal of the mission extension was to hunt for more near-Earth asteroids via a project called NEOWISE.
NASA has since funded the WISE team to combine all that data, allowing astronomers to study everything from nearby stars to distant galaxies.
These next-generation all-sky images, part of a new project called "AllWISE," will be significantly more sensitive than those previously released, and will be publicly available in late 2013.
"I had pretty much written off using WISE to find distant galaxy clusters because we had to reduce the telescope diametre to only 16 inches to stay within our cost guidelines, so I am thrilled that we can find them after all," said Peter Eisenhardt, the WISE project scientist at NASA`s Jet Propulsion Lab, California, and study author.