Orbits
An orbit is the path an object in space travels around another. Lots of objects in the Universe orbit others. The Moon orbits the Earth.
- Why do orbits happen?
Orbits happen because of gravity and something called momentum. The Moon's momentum wants to carry it off into space in a straight line. The Earth's gravity pulls the Moon back towards the Earth. The constant tug of war between these forces creates a curved path. The Moon orbits the Earth because the gravity and momentum balance out.
Momentum
If an object is moving, it has momentum. This is what keeps an object moving in the same direction. The more momentum something has, the harder it is to change its direction or bring it to a stop.
So we can work out an object's momentum using the equation:
Momentum = mass × velocity
During an explosion or collision, the total momentum is conserved. This means the total momentum before the event is equal to the total momentum after the event. This is useful for studying collisions in space or stellar explosions.
Measure a Day on Jupiter
Investigate Day and Night
On Earth, night follows day and day follows night. But why?
Complete this fun investigation to find out!
Measure the Sun's Rotation
Why Do Shadows Change Over Time?
Have you noticed that your shadow changes over time? The cartoon on this page shows why shadows change during the day.
How Do Satellites Stay In Orbit?
A satellite is an object which orbits another. An orbit is the curved path that an object in space takes around another object.
Explore Day and Night Around the World
Do different parts of the world experience day and night at the same time? Why do parts of the Earth have seasons? What are days and nights like at the north and south poles?