Last night a 900 foot wide asteroid made the latest in a series of close approaches towards Earth.
There is a chance it could collide with the Earth in 2036, the biggest threat would be if it fell on land mass.
Speaking to ITV Daybreak, Dr Maggie Aderin-Pocock said if it hits a city it would cause devastation.
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The Duke of Cambridge said his children were beginning a "lifetime of friendship" with Canada as they began their tour of the country.
When and where are they on, and how do they work?
What better, more dramatic spectacle has there ever been on American television?