A “PLANET killer” asteroid has been sighted heading towards the Earth’s orbit, but there’s no need to worry about it hitting our planet anytime soon.

The 2km-wide space rock, named 2022 AP7, will cross the Earth’s orbit according to Scott Sheppard and Carnegie Institution for Science researchers.

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Writing in the Astronomical Journal, they said the asteroid is within the top five per cent of the largest ever discovered.

Sheppard said: “Any asteroid over 1km in size is considered a planet killer.

“The Earth’s surface would likely cool significantly from sunlight not getting to the planet. It would be a mass extinction event like hasn’t been seen on Earth in millions of years.

“It has no chance to hit the Earth, currently.”

However, the Washington-based scientist warned we cannot predict what could happen when it enters the earth’s orbit and could drift closer to the planet.

"This will be centuries into the future and we do not know the orbit of 2022 AP7 precise enough to say much about its dangers centuries from now.”