A multi-national space mission including astronauts from the UK, the USA and the Soviet Union venture into space but they experience technical problems resulting in the mission being aborted, but unfortunately this is just the first in a chain reaction of events which results in catastrophic disasters back on Earth, including scores of asteroids, earthquakes and extreme weather.
The Day the Sky Exploded is fairly notable for being the first Italian sci-fi movie. Having said that, this is a fairly limited claim to fame given science fiction wouldn't exactly go on to become one of the movie sub-genres that the pasta masters are most well remembered for. This one is fairly ahead of its time in some respects though and quite ambitious for its time. It also is unusual in that it showed Americans and Russians working happily together at the height of the Cold War. So, it has some interesting things about it for sure but on the whole it was pretty forgettable stuff unfortunately. Interestingly, it was also photographed by the great future directing legend Mario Bava; to be honest, the version I saw this was a public domain pan-and-scan copy in which it was difficult to really tell if it had great cinematography or not sadly.