Earth is the one place in the universe that we know supports life. How does it support life? Well it has running water, in all three forms, a liquid, a solid, and a gas. It has an atmosphere that protects us from the sun's harmful UV rays. The earth also has a climate that is not too hot, and not too cold.


The Earth has four seasons. Summer, Winter, Spring, and Fall. These seasons all happen because the Earth rotates on an axis. It takes 24 hours for the Earth to make a complete 360 once. Many humans know this as the day. It takes 365 days for the Earth to make a complete circle around the sun once. This is known as the year. Because of the year, we have seasons. The side of the Earth that is facing the sun is experiencing Summer and Spring. These seasons are the hottest days of the year, and also the longest. They're the longest because they are facing the sun, therefore getting more sunlight. The side of the Earth that is facing away from the sun is experiencing Fall and Winter. This is how the seasons work on Earth.


The planet Earth is getting up there. Scientist estimate that the Earth has been around for nearly 5 billion years. This is a pretty long time. So as far as we know, Earth has been supporting life for this long. It started with the dinosaurs, and they were wiped out. Then came us, the humans. This is a very long time to support life, and we hope it continues to in the future.


The Earth has one moon. We have no fancy greek goddess as a name for it, just moon. Louis Armstrong was the first person ever to visit the moon. He made the famous quote, "One small step for man, one giant step for mankind." Earth is the fourth planet from the sun, and fifth largest behind Jupiter, Saturn, Uranus, and Neptune, the four gas giants. Once again, it takes 24 hours for one revolution, and 365 days for a complete trip around the sun. The atmosphere of the earth is made up of 78 percent nitrogen, 21 percent oxygen, and 1 percent argon. The atmosphere is made up of 4 layers, the first being the trophosphere. This is the 1st section and the most dense. The temps. range from 17 degrees to -52 degrees. The tropopause leads into the next layer, the stratosphere. The is section is dry and less dense. The Ozone layer is in this layer of the atmosphere. The Ozone protects us from the harmful UV rays of the sun. The next section is the mesosphere. The temp. here is below -93 degrees celsius. Here, the chemicals absorb energy from the sun. The chemicals are in an "exited" state. The next and final section of the atmosphere is the thermosphere. This section is the hottest, at 1,727 degrees celsius.


A person's birthday on Earth is once every year. For example, if your were born May 18, 1989. Your next birthday would be on May 18, 1990, and so on. If the sun were 615 mm, Earth would be 5.4 mm. That's the scake model of earth to the sun. Since we live on the Earth, we don't have to use space probes to explore the planet.

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