Question: thanks for answering my question but here is another one. what cause a meteor shower? also, how do we know when they take place?

Natasha Stephen answered on 18 Jun 2014:

Meteor showers occur when there is material in space that passes through our upper atmosphere and starts to burn up. That burning is seen as the little tails you see shooting across the skies, i.e. shooting stars.

Because the Earth rotates on a fixed orbit around the sun, we can predict when we will be passing through a region of space where this loose material exists, perhaps close to the asteroid belt where there has been a past collision and therefore a lot of leftover, loose material. If we can predict when we will pass through a ‘messy’ area of space, we can guess that we will see a meteor shower during this period of time!