What are shooting stars and how are they formed? What are shooting stars? How are they formed and how often do they occur during the night?

Also, why are there more shooting stars on some nights than on others?
A shooting star is simply the visible path a meteriod takes burning up in the atmosphere. As it flies through the atmosphere, it leaves a trail of fire, creating the streak of light you see.

Before they enter the atmosphere, they are simply chunks of rock. They could form in one of many ways - be broken off of a planet, etc. After they do this:



they look like this:



As for the reasons for meteor frequency varying, it's because of where the Earth is in it's orbit around the sun. Since almost all meteors are in orbit around the sun, and there tend to be clumps of them, this makes a 'donut' of meteors in orbit around the sun.

When the earth intersects one of these donuts, there is a spike in meteor activity. Ultimately, it's about how many space-rocks happen to hit Earth.

One annual 'high', for example, is the Perseid peak, which tends to occur mid-late summer each year. Sometimes, this even delays launches of space vehicles.