LONG BEACH, Calif. -- Space is typically thought of as a very quiet place. But one team of astronomers has found a strange cosmic noise that booms six times louder than expected.
The roar is from the distant cosmos. Nobody knows what causes it.
Of course, sound waves can't travel in a vacuum (which is what most of space is), or at least they can't very efficiently. But radio waves can.
There is "something new and interesting going on in the universe," said Alan Kogut of NASA's Goddard Space Flight Center in Greenbelt, Md.
In July 2006, the instrument was launched from NASA's Columbia Scientific Balloon Facility in Palestine, Texas, and reached an altitude of about 120,000 feet (36,500 meters), where the atmosphere thins into the vacuum of space.
ARCADE's mission was to search the sky for faint signs of heat from the first generation of stars, but instead they heard a roar from the distant reaches of the universe.
"The universe really threw us a curve," Kogut said. "Instead of the faint signal we hoped to find, here was this booming noise six times louder than anyone had predicted."
Other radio galaxies also can't account for the noise – there just aren't enough of them.
"You'd have to pack them into the universe like sardines," said study team member Dale Fixsen of the University of Maryland. "There wouldn't be any space left between one galaxy and the next."
"We really don't know what it is,"said team member Michael Seiffert of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"This is what makes science so exciting," Seiffert said. "You start out on a path to measure something – in this case, the heat from the very first stars – but run into something else entirely, some unexplained."
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