It may seem like Earth is always changing. That is because it is! However, many of these changes form patterns. A pattern means that they repeat themselves over and over again. In fact, there are patterns all around us.

Take the tides, for example. If you were to build a sand castle and leave it on the beach, what would happen to it? Most likely, it would be gone by the morning. This happens because tides come up on the beach. High tide means that the water comes up higher on the land. Low tide means that the water falls back. High and low tides each happen twice in a 24-hour day. So, if you make a castle at low tide, soon, the water will cover up parts of the beach, when the tide gets high.

Take the tides, for example. If you were to build a sand castle and leave it on the beach, what would happen to it? Most likely, it would be gone by the morning. This happens because tides come up on the beach. High tide means that the water comes up higher on the land. Low tide means that the water falls back. High and low tides each happen twice in a 24-hour day. So, if you make a castle at low tide, soon, the water will cover up parts of the beach, when the tide gets high.

You can notice another pattern by just looking at the Moon. Each night, the Moon changes the way it looks. Sometimes, you see a full moon. Sometimes, you see a half moon. Sometimes, you see no Moon at all. It all depends on the positions of the Sun, Earth, and the Moon. The phases of the Moon (the shapes of the Moon that we see from Earth) are always predictable. They happen in the same order, over and over again.

We see these phases because only one-half of the Moon’s surface is facing the Sun at any given time. At different times of the month, we can see different parts of the lit surface. We can see this because of where we are positioned in the Earth-Sun-Moon system.

The seasons are another pattern caused by the positions of Earth and the Sun. Earth is tilted and travels in an orbit around the Sun. Our summer occurs when Earth’s northern hemisphere is tilted toward the Sun as it moves along its orbit. During this time, the northern hemisphere receives stronger rays from the Sun. This causes the warmer temperatures during summer. In winter, temperatures are colder, because the northern hemisphere points away from the Sun and receives weaker rays from the Sun. During our winter, however, the southern hemisphere is tilted toward the Sun, so they are having their summer!

Yes, Earth may always be changing. However, we can predict many of these changes. These changes happen in the same way, over and over again.