Trending Science: This is how bright the universe is Scientists claim to have measured all the starlight ever created. © sripfoto, Shutterstock The universe is all around us, and its near and distant stars born as far back as several hundred million years ago are waiting to be discovered. From ancient to modern-day astronomers, humankind has been exploring the universe’s bright lights because they have been so much a part of each and every civilization. So how much visible light is there in the known universe? According to the journal ‘Science’, an international team of astrophysicists has now managed to measure all of the starlight ever produced throughout the history of the observable universe. “This has never been done before,” Marco Ajello, lead author and astrophysicist at South Carolina’s Clemson College of Science told the British newspaper ‘The Guardian’. To determine the history of star formation, Ajello and his team at Clemson analysed about 9 years’ worth of data from NASA’s Fermi Gamma-ray Space Telescope – one of the world’s best gamma-ray detectors. This data concerns gamma-ray signals from 739 blazars. Blazars are galaxies that contain supermassive black holes able to release narrow jets of energetic particles that leap out of their galaxies and streak across the cosmos at nearly the speed of light. Their black holes are millions to billions of times more massive than our sun. The team used blazars at various distances from us to measure the total starlight at different time periods. For instance, it calculated the total starlight of each epoch – one billion years ago, two billion years ago and six billion years ago – all the way back to when stars were first formed. How many photons has the universe produced in its long life? Using new methods of starlight measurement, they found the number of photons – the smallest unit of light – that escaped into space after being emitted by stars translates to 4x10 to the power of 84, or 4 followed by 84 zeroes. “By measuring how the starlight evolves throughout the universe, you can actually transform this into a corresponding measurement of star formation,” Ajello told Space.com. “We track down exactly how this changed during the history of the universe.” The astrophysicists based their calculation on measurements of the extragalactic background light (EBL), a collection of photons generated by all the stars and all the black holes in the universe. EBL is the part of near-infrared, optical and ultraviolet radiation produced by stars that’s able to make it out into space, instead of colliding with the dust that surrounds those stars. Starlight that escapes galaxies ultimately becomes part of the EBL. “It’s basically starlight that ended up everywhere,” Ajello explained. “All the light emitted by stars that is able to escape to space basically becomes this background.” The findings provide new insight into the first billion years of the universe’s history, a period that hasn’t yet been explored by today’s satellites. “Our measurement allows us to peek inside it,” said Ajello in ‘The Guardian’. “Perhaps one day we will find a way to look all the way back to the big bang. This is our ultimate goal.” Countries United States
