REASON ONE: ATMOSPHERE
Earth has a breathable atmosphere. Oxygen is the gas that is required for the life of most creatures. This is present in Earth's atmosphere, along with nitrogen. Oxygen is constantly put into the atmosphere by plants and trees.
Fortunately, Earth's atmosphere does not contain much carbon dioxide, a poisonous gas which makes up most of the atmosphere of planets like Venus and Mars.
The Earth's atmosphere is kept on the planet by its pull of gravity. Mars and Mercury are too small to keep atmosphere. As a result, Mercury has no atmosphere, and Mars' atmosphere is very thin, containing gases which have not managed to escape into space yet.
Earth's atmosphere is thick enough to prevent poisonous rays of radiation from getting through it
REASON TWO: CLIMATE
REASON FIVE: THE SUN
All of the reasons given above for life existing on Earth are only possible because of one main reason. The Sun! Put simply, if there was no Sun, there would be no life on Earth. Technically, Earth probably wouldn't exist either!
Because of Earth's ideal distance from the Sun, it receives the perfect amount of heat and light to allow life to be created and to support it.
Imagine what would happen if the Sun suddenly vanished. How would you keep warm? How would you see? How would you get food and drink? How would plants and trees grow? How would they photosynthesize? Where would Earth go? The Sun's gravity keeps Earth in its orbit, but if the Sun vanished, Earth would simply float away.
Earth has a suitable climate.
This is caused by the moderate amount of carbon dioxide in the planet's atmosphere, which is constantly refreshed
The temperature on Earth does not go from one extreme to the other either. Mercury can be anything from 200°c below freezing to 375°c above. At 375°c, water would only exist as a gas, and the planet would be completely dry. Venus has a surface temperature of 480°c, which would be much too hot for anybody to live in. Mars, although it can reach 25°c, can be as cold as -140°c, a temperature which would freeze blood and water.
The other planets are colder still.
REASON THREE: WATER
REASON FOUR: LIGHT
Earth
Why is there life?
Joshua Lopez
GT
Mrs.Almager
6th period
Earth has water!
Water is believed to be the most important chemical necessary for life. It is drinkable, and it allows life-providing molecules to move around easily.
Other moons in the Solar System, such as Europa, a moon of Jupiter, are believed to have oceans of water under its icy surface. Scientists believe that, if they could find traces of water on Mars, the possibility of life existing on that planet would be greatly increased.
Water on Earth can be found anywhere, in its three states. It can be frozen, taking the form of ice. It can be liquid, seen in seas and oceans and lakes. It can also be a gas, seen as clouds
All planets receive light from the Sun, but no planet uses it as usefully as Earth. Trees and plants on the planet produce oxygen through a process called photosynthesis. Plants need the Sun to grow. It is believed that if we were able to get plants to grow on another planet, such as Mars, they would begin putting oxygen into the planet's atmosphere and increase the possibility of life.
Saturn's moon, Titan, has an atmosphere containing mainly nitrogen. If this moon was to possess oxygen too in its atmosphere, by a plant photosynthesizing on it, it could have a similar atmosphere to Earth.
Something else which helps the plants to photosynthesize on Earth is the length of time the planet takes to spin once on its axis. Taking just under 24 hours means that each side of the planet receives sunlight regularly. If we look at a planet like Venus, which takes 243 days to spin on its axis, it means that for a large period of time certain parts of the planet are in complete darkness. So even if the planet could support life, it would struggle to do so.