Scientists have found natural sugars floating in interstellar space – and it could fundamentally change the search for alien life.Researchers spotted erythrulose, found Earth in raspberries and fake tan, towards the middle of our galaxy.It could help answer one of the biggest questions about the origins of life on Earth, and how it could have formed elsewhere in the universe.Sugars are central to living organisms: they are the backbone of the DNA and RNA that makes us up, and help power key biological processes. Researchers also think they would have played a key role in the beginning of life.But despite that importance, astronomers still do not know how those sugars could have formed, here or elsewhere. Experiments in laboratories, for instance, show that they would not form in the conditions that were around before life was.Astronomers have previously found sugars on samples from meteorite and asteroids, suggesting that some of them might have come from the primordial molecular cloud that formed our solar system. But no samples had been found in the interstellar medium that sits between stars in space.Now, researchers have found such a sample towards the molecular cloud known as G+0.693−0.027, which is near the middle of our Milky Way galaxy.They spotted it using the ultra-sensitive surveys powered by two powerful telescopes.In data from those telescopes, researchers found data that matched erythrulose when it is measured in a laboratory.That research also showed that the complex sugar – which is the only possible four-carbon ketone – is vastly more common than similar, less complex three-carbon sugars, of which they found none. “This finding was unexpected, as the prevailing view in astrochemistry is that interstellar molecules grow in size through the sequential addition of carbon atoms”, said Izaskun Jimenez Serra, the lead author on the new work.That suggests that the some 0.5 and 50 million tonnes of the sugar could have arrived on Earth during the Late Heavy Bombardment, about 4 billion years ago. In doing so, it might have helped start the development of life on Earth, the researchers said.The work is published in a new article, ‘Detection of a chiral four-carbon sugar in interstellar space’, published in the journal Nature Astronomy.