A signal that began 9 billion years ago arrived from space

For the first time, scientists have detected a signal from another galaxy located 9 billion light years from Earth.

The radio signal was picked up in Pune, India by the Giant Meterwave Radio Telescope (GMRT), a giant radio telescope featuring an array of 30 satellite dishes all pointed skyward, with each dish about 45 meters in diameter.

Using this advanced telescope, scientists have detected a unique radio signal with a specific wavelength known as the 21 cm line or hydrogen line because it is emitted by neutral hydrogen atoms. So there are no aliens in a flying saucer: the signal was sent by SDSSJ0826+5630, a “star-forming” galaxy. The startling aspect of this signal is that it was emitted when the Milky Way was a young galaxy “only” 4.9 billion years old: a very few, if the Milky Way is currently estimated to be 13.8 billion years old.

According to accounts, the signal took more than 8.8 billion years to reach Earth: a journey through time that allows astronomers to “look” back in time nearly 9 billion years ago. Literally astronomical distance, making SDSSJ0826+5630 the farthest signal detected to date.