Earth

4 Pages 892 Words

Earth
My topic of choice is the planet Earth. I chose this planet because there is no other planet like it that we know of. It is the only planet that can support life again that we know of. Obviously there is no other plant that I would know more about than earth, probably because I live on it.
What is required for a planet to be able to support life? This is a question that people have been trying to answer for many years. Earth is a very unique planet because it is the only one proven to support life. Living organisms need certain things in order to survive that are not found on any other planet. Some of these life supporting features include food, water, atmosphere, temperature, rotation, gravity, surface and a moon.
First, living things need a source of food. Energy is needed in order for living things to grow. Our main source of energy on Earth comes from the sun. Plants use the light from the sun for photosynthesis, and plants source of food comes from photosynthesis. While animals don’t need the sun to produce their own food they do eat plants, and all plants go through photosynthesis. Planets that are far from the sun, such as Pluto, can not use the sun’s light to produce food. Photosynthesis could never happen on Pluto. Therefore, there will never be any life on Pluto.
Living things also require water. Plants and animals both need fresh liquid water. Water is important to living things because it helps change energy from one form to another, such as light to food. Earth is the only planet known to have a large amount of liquid water. Mars does have polar ice caps, but no liquid water. Life can not survive on a planet with no liquid water.
Another unique feature of Earth is its atmosphere. A planet without an atmosphere, like Mercury, could never have any life. Living things have to breathe. If there is no atmosphere, then there is no gas for plants and animals to breathe. Our atmosphere contains oxygen and car...