Scientists say an asteroid almost twice the height of the Shard in London will pass by Earth early tomorrow morning.
It's one of two that NASA has described as "relatively medium-sized".
The first is due to pass overhead today, with the second larger rock expected some time in the early hours of Sunday morning.
According to NASA data, it's between three and six-hundred metres wide and they've reassured us that they've done all the sums and have ruled out any possibility of it posing any danger to the planet.
The space rock will fly by around three million miles from Earth at more than 14-thousand miles per hour.
