Our Planet
by Abby Cessna on December 31, 2009



Our planet is the third planet from the Sun and the fifth largest of the eight planets in our Solar System. It is located between Mars and Venus, which are also terrestrial planets. Earth has a number of nicknames including the Blue Planet and Terra. The most remarkable thing about our planet is the life that thrives all over our planet. Not only are there plants, but there are also animals, sea creatures, birds, and other diverse species.

Scientists have often tried to discover what makes earth such an ideal place for sustaining life. The Earth has been described as being in the habitable zone, which is a theoretical area in a Solar System where the conditions are optimal for the existence of life. Scientists are using the habitable zone to find extrasolar planets that may be able to support life. Earth is also the only planet in our Solar System with tectonic plates. The plate tectonics help protect our planet from overheating like Venus because the carbon in plants makes its way back into the Earth and is recycled. Liquid water is also an important element for life. Just over 70% of Earth’s surface area is water.

Our planet’s atmosphere helps keep heat trapped around the planet as well as protects us from the vacuum of space. The atmosphere is comprised of a variety of chemicals. It is mostly nitrogen (77%) and oxygen (21%). It also contains small amounts of water, carbon dioxide, argon, and other substances.

Earth is the densest planet in the Solar System, with an average density of approximately 5520 kg/m 3, which is more than five times the density of water. The planet is so dense because it is composed of large amounts of iron. Most of the iron is concentrated in the core which is 88% iron. Because the planet is so dense, its gravity is great compared to its size. The temperature on our planet is not as extreme as the temperature of the other planets. The lowest recorded temperature on Earth is approximately -89°C in Antarctica while the highest recorded temperature is 58°C.  The diameter of the planet is 12,742 kilometers, and the volume is 1,080,000,000,000 km3. The planet is not a perfect sphere. It is actually an oblate spheroid. That means it is squished at the poles, so it bulges out at the equator. This is caused by the speed of the Earth’s rotation and is common with all the planets.

Universe Today has articles on the size of the Earth and gravity of the Earth.

You should also try Earth and all about Earth.

Astronomy Cast has an episode on Earth.

Reference:
NASA Solar System Exploration Guide: Earth

Last modified: Tuesday, 13 September 2011, 2:53 PM