Mean anomaly

Let's start with what an "anomaly" is. Anomaly means something that is different or unusual. In space, when we want to know where a planet or moon is at a certain time, we use a special way of measuring its position based on its orbit (the path it takes around its star or planet). This measurement is called an "anomaly" because it tells us how far the planet or moon is from a certain point on its orbit.

The "mean" part of mean anomaly just means average. So, the mean anomaly is the average distance a planet or moon is from that certain point on its orbit over time. It can help us predict where it will be at a future time even if it doesn't move in a completely regular pattern.

Think of it like this, imagine you are riding a bike around a circular track. Every time you complete a lap, you end up back where you started. Now, imagine that you have a watch that tells you how far around the track you are. If you start the timer when you cross the starting line, the watch will show you your "anomaly" at any given time. The "mean anomaly" would be the average distance your bike is from the starting line over time, taking into account any changes in speed or direction you might make.

So, in short, mean anomaly is a way of measuring the average distance of a planet or moon from a certain point on its orbit over time, which can help us predict where it will be in the future.