Before we set out on our journey through the solar system, we must first take a look at our home planet. Earth is the only planet that has life on it in our solar system. This is for two main reasons. First, our planet has water. In fact, our Earth is 70% percent water! Why is Earth the only planet in our solar system that has water? The distance from the Sun to Earth is what allows so much water to exist on earth. If the Earth where closer to the Sun it would be too hot for water to exist. Also, if the Earth was further away from the Sun, it would be too cold for liquid water to exist on Earth. We are in the perfect spot in the solar system to have water on our surface! Having so much water allows the water cycle to occur on Earth. This keeps lakes, streams, and oceans full and plants watered. Take a look at our "water planet," Earth, in the video below.
Along with water, Earth also has an atmosphere that allows life to survive. As we will see on our journey through the solar system, other planets have atmospheres, but the Earth's atmosphere works just right to allow life to survive on earth. Our atmosphere is made of five different layers of mostly the elements nitrogen (78%) and oxygen (21%). The Earth's atmosphere is like a big blanket that lies over the earth. This blanket prevents dangerous light from the Sun from hitting earth. It allows just the right amount of sunlight to reach Earth. The atmosphere also stops meteors from hitting the earth. It acts as an insulator. We have learned before that insulators do not absorb heat quickly. Our atmosphere keeps a certain amount of warm air on Earth so that the Earth's temperature stays the same. Last, weather occurs because of our atmosphere. Precipitation from different types of weather allows the water cycle to continue on Earth. Learn more about the Earth's atmosphere below with Bill Nye the Science Guy! You only need to watch the first five minutes of the video.
Recently, a skydiver named Felix Baumgartner jumped out of an aircraft at a height greater than anyone ever had before. He jumped from a height that was actually above the Earth's atmosphere! In this video, you can see what the Earth's atmosphere actually looks like. The blueish tint you see around the Earth before Felix jumps is the Earth's atmosphere.
Want to know more about the Earth's atmosphere? Check out the website below.
A friend of yours would like to know why Earth is the only planet that has life on it in our solar system. In a paragraph, explain to them what allows us to have life on Earth.