NASA asteroid DANGER: How often do asteroids hit the Earth?

Such a space rock could easily obliterate New York, also causing a magnitude 8 earthquake that might be felt than 1,000 miles away.

And once every few million years, an asteroid large enough to threaten the existence of life Earth arrives.

NASA believes asteroids larger than one mile (two kms) will have worldwide effects.

Apart from the main impact, the quantities of dust tossed would block the sun and lead to rapid changes in climates across Earth.

At 5.4kms in diameter, the largest known potentially hazardous asteroid is Toutatis.

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