[space] orbits and satellites

[ https://www.bbc.co.uk/bitesize/guides/zt2fcj6/revision/1 ]

Orbit

The path taken by an object around a star, planet or moon.

Natural Satellite

Objects that orbit the earth that are not man made, like the moon.

Artificial Satellite

Objects that orbit the earth that are man-made.

Polar Orbits

Polar orbits take the satellites over the Earth's poles.

Geostationary Orbit

Satellites take 24 hours to orbit the Earth, so the satellite appears to remain in the same part of the sky when viewed from the ground.

Elliptical Orbit

An oval shaped path, used to describe the shape of the Earth's orbit around the Sun.

Period

Time taken to complete an orbit

Velocity

Speed in a given direction (m/s)

Acceleration

Rate of change of velocity (m/s²)

Centripetal Force

The resultant force towards the centre of a circle acting on an object moving in a circular path.

Resultant Force

The single force that could replace all the forces acting on an object, found by adding these together.

The gravitational attraction between two objects decreases with distance...

this means that the closer the two objects are to each other, the stronger the force of gravity between them. If the force between them is greater, a greater acceleration will occur.

The greater the acceleration...

the greater the change in velocity - this causes the object to move faster.

Asteroids

Rocks in space which orbit the Sun in highly elliptical orbits but may cross the Earth’s orbit, producing a small risk of collision.

Comet

A ball of icy rock that follows an elliptical orbit around the Sun. As this approaches the Sun, it begins to vaporise, which means that it turns into a gas. It then produces a distinctive tail.