# Revise GCSE Physics

Question:What would happen here on Earth if a large asteroid where to strike the surface of the Earth?

Large Asteroids have collided with the Earth in the past.

65 million years ago, an Asteroid crashed into the Yukatan peninsula in Mexico, and although it is believed to have been only 10km in size it is believed to have contributed to the extinction of the Dinosaurs.

However there is a negative correlation between the size of an asteroid and the frequency with which that size of asteroid hits the Earth.

Asteroids 10km in diameter hit the Earth only once in every few hundred millions of years.

A 1km asteroid is expected to hit the Earth on average every 500,000 years, but there may be one due in 2880.

When an asteroid collides with the earth it can be travelling at up to 40 kilometers per second, which is very fast.

Some of this speed is actually due to the movement of the Earth which is travelling around the sun at about 30 kilometers per second. (you travelled a quarter of a million kilometres around across the Solar System while you slept last night!).

Because of the mass and speed of the Asteroid the impact has tremendous energy.

A sufficiently large impact could cause life on Earth to end!

The effects of the asteroid impact fall into two groups. Local and global.

Locally: The impact will certainly cause the formation of a crater, and out of the crater hot (even molten) rock material will be thrown over considerable distances. The ejecta will cause widespread fires. The impact might also cause earthquakes and Tsunamis.

Globally: The dust thrown up by the impact can block out the Sun's light for long periods of time. The time for the dust to settle back to the surface could run from months into years, and the dust would quickly spread around the whole Earth. This would cause a very rapid change to the Earth's climate, which would lead to the extinction of species, including Man.

Reduction in the amount of Sunlight reaching the Earth's surface would cause the planet to cool rapidly and plants to die for lack of photosynthesis followed by all the animals dying.

Some people could certainly survive, using stored fuel for heat and stored food until sunlight was restored, and the evidence suggest that life has also resumed after large impacts in the past, so plants presumably started growing again fairly quickly.

Summary for Exam: The consequences of a collision with a large asteroid include:

1: The creation of a crater

2: The ejection of hot rocks