Astronomers on Monday reported the discovery of a giant hydrogen cloud that could be an unborn galaxy and that possibly provides evidence that new star systems are still being formed.
Scientists from the National Science Foundation and Cornell University accidentally discovered the cloud--10 times larger than our own Milky Way galaxy--while adjusting a radio telescope in Arecibo, Puerto Rico.
Many astronomers have thought that all galaxies were formed billions of years ago, shortly after the "Big Bang." But other scientists have argued that some galaxies may still be forming.
Riccardo Giovanelli, a radio astronomy expert with the Science Foundation, said he considers the newly discovered cloud the best proof yet that galaxy formation is continuing.
The hydrogen cloud, discovered by Giovanelli and Cornell's Martha Haynes, is 65 million light-years, or 384 sextillion miles, from Earth--relatively close on a galactic scale--and located south of the Virgo cluster of galaxies.
Galaxies form when such hydrogen clouds gradually condense to form stars and planets. A typical galaxy contains about 10 billion to 100 billion stars. Before the discovery of the new cloud, Giovanelli said other large gaseous objects have been found in space but have been associated with existing galaxies.
Because the cloud has not yet condensed into stars, it does not give off visible light and emits only radio waves. That is why it has gone undetected in past optical surveys of space.