The stars are not actually "in" the sky – they are giant balls of hot gas that are very far away from Earth, in space. Here's a breakdown of how we see them:

* Stars are giant balls of hot gas: Stars are made mostly of hydrogen and helium, and they generate light and heat through nuclear fusion in their core.

* Light travels from stars to Earth: This light travels through space as electromagnetic radiation, and it takes a very long time to reach us. For example, the light from the sun takes about 8 minutes to reach Earth.

* We see stars at night because the sun is on the other side of the Earth: During the day, the sun's light is so bright that it washes out the light from the stars. However, at night, when the sun is below the horizon, we can see the stars because there is less sunlight to interfere.

The Earth's rotation and orbit also affect how we see the stars:

* Rotation: As the Earth rotates on its axis, we see different parts of the sky throughout the night.

* Orbit: As the Earth orbits the sun, we see different stars at different times of the year.

So, in short, the stars are always there in space, but we only see them at night when the sun's light doesn't interfere.