What can scientists learn from a stray SpaceX rocket hitting the Moon?

The spent stage - which is about the size of a five-storey building and weighs at least 4,000kg - was left drifting in a long, looping orbit that swung out towards the Moon and back again. Over the next 18 months, the gentle gravitational tug of the Earth, Moon and Sun, along with even light from the Sun, gave a faint push. Astronomers tracking the rocket part eventually worked out that those small nudges had put it on a course towards the Moon and was picking up speed every day.The impact at around 07:35 BST (06:35 GMT) on Wednesday happened in broad daylight for many parts of the world, but the tiny flash it produced would have been far too faint to see, even through a telescope. Amateur astronomers observing in darkness would also have had little realistic chance of seeing the flash, given that it would have lasted a fraction of a second. But they may have seen a plume of dust stretching as far as 100km (62 miles) that lasted for several minutes.Even spacecraft orbiting the Moon were not in the right place at the right time to watch the impact happen live. South Korea's Danuri orbiter had the best chance, having passed near the crash site shortly beforehand. Its team has told Korean media that any footage will only be released once researchers have completed their analysis.Over the next few days, Nasa's Lunar Reconnaissance Orbiter will be in position to photograph the site, allowing images before and after the crash to be compared.