Astronomers have peered into the early universe and spotted a trove of baby galaxies huddled together, in what may be the oldest galactic clusters yet discovered.
Galaxies like our Milky Way cluster together today, but how they formed these cosmic clubs has remained a mystery until now.
Light from these newborn galaxies traveled vast distances—10 billion to 11 billion light-years—to reach the two space telescopes that detected them. So the light we see now shows the galaxies as they were some 10 billion to 11 billion years ago. The universe itself is thought to be 13.8 billion years old.
That places the newly discovered clusters very early in the universe's history, Brenda L. Frye of the University of Arizona's Steward Observatory and colleagues report in an upcoming issue of the journal Astronomy & Astrophysics.
The team used the combined power of two space telescopes, Planck and Herschel, and a natural magnifying lens effect to find the distant galaxies. (Read more about the search for ancient galaxies.)
First they combed through the massive all-sky survey maps produced by the European Space Agency's Planck mission as it mapped the radiation left over from the big bang. This data, in the far-infrared to radio parts of the spectrum, showcased 234 objects that the team now believes are precursors of clusters we see today. Next, NASA's Herschel Space Observatory resolved finer details to reveal that each black dot on Planck's map was in fact a dense concentration of galaxies.
Three of the young galaxies appear to be pumping out stars at high rates—up to 1,500 times the mass of our sun per year. (Read about a supermassive galaxy cluster that is spewing out stars.)
That answers one long-standing question. "It was not known whether young galaxies form stars gradually, like marathon runners pacing themselves, or in bursts," Frye said in a statement.
"It turns out these young galaxies were not forming slowly, but in a dramatic way,” he said. “Lighting up with star formation, they appear like fireworks going off in the sky. It's like sprinting the first mile of a 26-mile marathon, and then walking the rest of the way." (Read about a blast that shut down star formation.)
See for Yourself
Affectionately known to astronomers as "island universes," galaxies dot the entire observable cosmos. Our Milky Way is just one of billions, but it and its nearest neighbor, the Andromeda Galaxy 2.6 million light-years away, are the two heavyweight members of a small cluster of about 30 galaxies called the Local Group. (Sky-watching tip: Autumn is the best time to see our neighbor Andromeda.)
Autumn is the best time to see our neighbor Andromeda.
Peering deeper into intergalactic space at, say, around a few tens of millions of light-years, we find other similar groups of galaxies.
Head outside on any clear, moonless night in April and look toward the Virgo constellation low in the southeast. Here we encounter one of the most celebrated groups of galaxies: the Virgo cluster.
At about 60 million light-years from Earth, the Virgo cluster is made up of several thousand galaxies, peppered mostly with large spirals and some smaller elliptical ones. Our Local Group is considered an outlying member, in the suburbs of this giant Virgo supersize cluster of galaxies.
At this time of year, late nights reveal considerably fewer bright stars in the high southern sky than seen in winter. That's because this part of the sky looks away from our own Milky Way. Looking out above the disk of our galaxy, there are fewer stars blocking our line of sight to the rest of the universe.
One of the most brilliant late springtime stars is Arcturus of the Boötes constellation. Together with the other signpost stars of spring, Spica and Regulus of the constellations Virgo and Leo, this stellar trio forms the Spring Triangle—the best celestial hunting ground for galaxies.
Sweeping over this piece of celestial real estate with binoculars or a small telescope will show many objects known in stargazing circles as "faint fuzzies."
While stars appear as pinpoints of light, these cloudy patches in the eyepiece are in fact galaxies! Not very impressive or eye-catching by any means, it will have to be enough to simply know that the ancient beams of light hitting your eyes left on their journey around the time when dinosaurs still ruled our planet.