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People living in southern California were left puzzled recently, after a mysterious and golden fireball was seen lighting up the night sky.

Many thought it was a meteor shower or a comet - however experts say it was a piece of space junk re-entering Earth's atmosphere, which had come from a Chinese rocket involved in a recent space mission.

Such space junk showers have become more common in recent years as more countries and private companies send items such as probes, satellites and rockets into space.

But what is space junk and why is it a problem? Keep reading to find out.

The fireball was seen re-entering the Earth's atmosphere over the city of Los Angeles on the west coast of the US.

The bright sight left many people confused, with several people who witnessed the incident posting videos on social media and calling local radio stations.

After much speculation, it turned out that the fireball was likely to be debris left over from a recent space mission.

The Aerospace Corporation, a US space organisation, said in a statement that their findings suggest that the object seen "was the orbital module from the November 2022 Chinese Shenzhou-15 launch to their space station."

They added that they estimated the space junk to have a mass of about 1,500kg - the same as the total mass of an average car.

There were no reports of any debris landing on land and most pieces of space junk pose very little danger as they burn up into small pieces as they re-enter Earth's atmosphere.

Space junk is also sometimes called space debris. It could be bits of an old rocket that have failed or aren't in use any more, a broken satellite or even a screwdriver dropped by an astronaut!

As we send more things into space, lots of bits and pieces have been left behind.

Space junk orbits around the Earth because of our planet's gravity - the thing that keeps us on the planet - and keeps the Moon circling around us.

Although the danger to us living on Earth's surface is minimal because most space junk burns up in the atmosphere and doesn't reach land.

The junk that orbits the Earth is super fast - reaching speeds of up to 18,000mph (29,000km/h).

At these speeds even tiny pieces of debris can be a huge risk to astronauts living and working on the International Space Station (ISS), or travelling on spacecraft.

Space junk can cause problems for functioning space equipment too, such as satellites that are used for things like maps, mobile phones and the internet.

That means any collision with space junk could cause disruptions to technology here on Earth.

Companies and spaces agencies are also looking at ways to clear up the litter left behind.

They include devices that can catch satellites and pull them back down to burn up in the atmosphere, lasers to knock objects out of orbit and big magnets or claws that can grab the pieces of junk as they travel.