This asteroid is accelerating through space – scientists don’t know why

Whoosh! (Picture: Metro) An oddball object is racing through the solar system in a way science is struggling to explain. Asteroids, the crumbs of the early solar system, usually fly at a steady pace thanks to invisible forces like gravity and the sun’s radiation. Not KY26. Sometimes called 1998 KY26 for the year it was first spotted, this 36-foot-wide lump is accelerating in a way space rocks shouldn’t. Models of KY26 (Picture: Toni Santana-Ros et al/Nrco0e/Wikimedia Commons) Some scientists think it’s a so-called ‘dark’ comet’. Others suspect it’s an unidentified aerial phenomenon, as officials now call UFOs. It’s probably neither of these, though, researchers from Atlanta, Georgia, wrote a new paper published in Icarus. ‘KY26 is exceptionally bright,’ Korbin Hansen, an aerospace engineer at the Georgia Institute of Technology, tells Metro. ‘Combined with the asteroid’s quick rotation, this suggests that it may be a monolithic enstatite asteroid, which is a type of asteroid that has not been rendezvoused by a spacecraft before.’ Wait, what is a ‘dark comet’? And why isn’t KY26 one? Asteroids are rocks that can be as small as a baseball to as big as a building – and way bigger than that (Picture: Getty Images) Asteroids are made from dirt leftover from the birth of the planets, doing laps around the inner solar system but are largely idle. ‘Small asteroids like 1998 KY26 are likely chunks that broke off a larger parent asteroid after a violent collision,’ adds Hansen. Comets, meanwhile, are chunks of rock and ice that originate in the outer solar system with dazzling tails stretching for millions of miles. Sometimes, if they veer too close to the sun, these celestial snowballs melt and release gas and dust, giving them a mini speed boost. A ‘dark comet’ is something in between, Hansen says, a tail-less chunk of inert rock that seems to occasionally hit a comet-gradegas pedal. ‘It has been hypothesised that dark comets are accelerated by outgassing,’ says Hansen. ‘If this was the case, we would expect them to have significant quantities of water to act as “fuel”.’ Comets have a distinctive tail made of gassy ice (Picture: Getty Images) More than a dozen dark comets have been discovered so far, with most experts thinking KY26 was among them. But Hansen and his team think KY26 is too warm to keep the ice needed to power propulsion. Models showed the rock has an average temperature of -61°C, far warmer than the -128°C needed to retain buried water ice. KY26 is billions of years old and even if 1% of KY26 was ice, it would melt in 2,000 years. If that ice gave it speed, it would be gone in 62 years. ‘Y26 is among the smallest and fastest-rotating asteroids discovered to date,’ Hansen says. Hayabusa2, Japan’s asteroid hunter, will touch down on the surface of KY26 in 2031 (Picture: ESO/M. Kornmesser. Asteroid: T.) ‘While we do not disagree that its non-gravitational acceleration is high, our models show that the asteroid should be too hot to keep water. ‘Thus, it must be accelerated by a different means than outgassing – we specifically endorse the assertion that 1998 KY26’s acceleration is driven by solar radiation pressure: reflection and thermal reemission of light.’ We don’t know much about KY29, as Hansen said, because no space probe has ever visited. But one will in July 2031, when the Japanese space agency’s Hayabusa2 spacecraft gets up close to it. But… does Earth have anything to worry about? To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video In 2024, a ‘city-killer’ asteroid was spotted called 2024 YR4. The odds of it striking Earth kept rising and rising until scientists had enough info to conclude there’s next to no chance of it smashing us. There’s not too much we can do if an asteroid is barreling our way, experts previously told Metro, other than nudging it with a probe or nuclear bombs. KY26 is not on a collision course with Earth either, Hansen says. Plus, it’s more of a space pebble than a rock. Potentially hazardous asteroids must pass near Earth and be large-ish ‘KY26 satisfies the first criterion, as its minimum Earth intersection distance is very small, which is partially why the asteroid was discovered so early in spite of its small size,’ Hansen says. ‘This small size, however, is why 1998 KY26 fails to meet the PHA definition.’ Get in touch with our news team by emailing us at webnews@metro.co.uk. For more stories like this, check our news page. Arrow MORE: This is how space travel could transform our lives – and jobs – in just 50 years Arrow MORE: Discovery of two supermassive black holes have left scientists absolutely baffled Arrow MORE: Colossal ‘doomsday’ glacier set to melt triggering ‘catastrophic sea level rise’ News Updates Stay on top of the headlines with daily email updates.