The first light which ever shone in the universe has been detected by astronomers scouring the skies for the earliest stars.
Using a simple radio antenna positioned in the quietest place on Earth - the western Australian desert - scientists picked up a signal of the long-sought ‘cosmic dawn.’
The breakthrough was described as ‘revolutionary’, ‘trailblazing’ and the most important discovery in astronomy since the detection of gravitational waves in 2015.
It shows that the first stars appeared 180 million years after The Big Bang, which occurred 13.7 billion years ago. Before then the universe existed in a pitch-black emptiness of gases which scientists refer to as the ‘dark ages.’
But as stars began to burst into life, the skies were lit for the first time, and a host of new elements were created in the huge furnaces which would eventually allow life to form on Earth.
"Finding this minuscule signal has opened a new window on the early universe,” said astronomer Judd Bowman, of the Arizona State University, the lead investigator on the project.
"Telescopes cannot see far enough to directly image such ancient stars, but we've seen when they turned on in radio waves arriving from space.
“It is unlikely that we’ll be able to see any earlier into the history of stars in our lifetimes.”
Models of the early universe predict early stars were massive, blue and short-lived, but because telescopes cannot see them astronomers needed to look for changes in the background electromagnetic radiation emitted after the Big Bang, called the cosmic microwave background (CMB).
Astronomers theorised that starlight from the first stars would interact with hydrogen atoms, which would then absorb some of the background radiation, causing a dip in CMB radio signals.
But many scientists believed even if such a signal existed it would be too faint to ever be detected. The frequency they were searching for - 50 to 100 megahertz - was the the same as many radio stations on Earth and also the booming radio waves which emanate naturally from within the Milky Way.
Dr Peter Kurczynski, the National Science Foundation program director said: “It's like being in the middle of a hurricane and trying to hear the flap of a hummingbird’s wing.”
However in a new paper, published in the journal Nature, the astronomers said they had picked up a clear signal from the Murchison Radio-astronomy Observatory in Australia.
Prof Carole Haswell, Head of Astronomy at the Open University, said: "This is a very exciting result. For me the most interesting thing is that it reveals some of the properties of the first generation of stars in the Universe.
"There will be far-reaching implications for our understanding of the formation and early history of our Galaxy and all the other galaxies and clusters of Galaxies in the Universe. Wow!”
The researchers observed a a dip in the radio waves, at around 78 megahertz.
“That frequency corresponds to roughly 180 million years after the Big Bang,” said study co-author Alan Rogers, a scientist at MIT’s Haystack Observatory.
“This is the first real signal that stars are starting to form, and starting to affect the medium around them.”
The signal was spotted in 2016, but researchers have taken until now to verify their findings, ruling out all other potential sources, before announcing their work.
Dr Kurczynski added: “This discovery opens a new chapter in our understanding of how the world we see came into being.
“With an antenna not much different than an FM radio's, and a great deal of care and ingenuity, the researchers saw something not yet detected by interferometers requiring hundreds of antennas, complex data processing and hundreds of observing hours.”
Associate Professor Alan Duffy is Research Fellow in the Centre for Astrophysics and Supercomputing at Swinburne University of Technology said: “This detected silhouette would be a first of its kind, one of the earliest detections of forming stars/galaxies and acts as a trailblazing observation in low frequency radio astronomy for years to come.
“Yet that’s not even the most exciting part - it could be the very first confirmation of the dark matter particle.”
Antony Schinckel is Commonwealth Scientific and Industrial Research Organisation’s Head of the Square Kilometre Array Construction and Planning said: “This Nature paper describes an extremely important and exciting result.
“They have used a single antenna to watch the first stars turn on in the early Universe and to provide our first glimpse of the long-sought Cosmic Dawn.”
Professor Karl Glazebrook is Director of the Centre for Astrophysics & Supercomputing at Swinburne University of Technology added: “This is the most important astronomical discovery since the detection of gravitational waves in 2015."