Facts About Planet Earth
Find basic facts about our planet earth here.
Our Earth is the third planet from the sun and has a diameter of 7,905 miles. It orbits the sun once every year at a distance of 93 million miles away. Earth's atmosphere is made up mostly of nitrogen and oxygen. Seen from space, our home planet looks blue and white. The blue is the oceans, which cover two thirds of the surface. The white is clouds of water vapor in the atmosphere. Earth is the only planet in the solar system with a large supply of liquid water on its surface. This may be the main reason why it is the only planet know to have life. The Earth is surrounded by a magnetic field called a magnetosphere. This field protects the earth by trapping dangerous cosmic rays in zones inside the magnetosphere. These zones are called the Van Allen belts. The Earth, as our home, is interesting both in its own right in the solar system and also as an example of a solar system member. The features we find on Earth are often examples of what we find on other planets. Good examples of this are mountain ranges which are typical not only of the Earth but also of Mercury, Venus, Mars, our moon and the moons of other planets.
When astronauts began traveling into space and looked back at the Earth we finally realized just how fragile a planet we live on. Photographs that were taken showed that we are on an oasis in space. This helped us to realize that we must learn to keep our planet safe and habitable. Spacecraft, outside the earth's atmosphere, could study the Earth in new ways. Photographs taken with ultra violet light showed a faint halo of low density hydrogen gas that surrounds the Earth. As viewed from the moon, the Earth appears as a crescent, since half the Earth is always lighted by the sun. Interestingly, traveling in space often gives us a new prospective on familiar objects. Since astronauts and satellites orbit the Earth in about 90 minutes, they will see 18 sunrises and 18 sunsets each day.
The greater the distance a satellite is away from the Earth, the longer it takes to orbit. At an altitude of 22,000 miles away from the earth, a satellite takes 24 hours to orbit the earth one time. Since the Earth rotates at the same rate underneath to a person on Earth the satellite appears to be hovering. We therefore put communications satellites in what is known as geosynchronous orbits, synchronized with Earth's. Many of our television pictures as relayed to us by these satellites. Weather satellites are also in geosynchronous orbits. They photograph the Earth every few minutes and radio the information back to Earth.
NASA is planning a mission to the planet Earth using space satellites to monitor the ozone in our air, the fish in our oceans, the temperature of the oceans and the continents, smoke from forest fires, eruptions of volcanoes and many other aspects of Earth and of life on Earth. Studies of the Earth's weather have also provided valuable information. We learn even more about basics of weather and climate by studying the Earth from space. Storms and weather systems develop circular patterns because of the rotation of the Earth. Since the Earth has a solid surface, all points on its surface rotate once around in the same length of time. Points on the equator have farther to go in that time than do points at higher or lower latitudes. The poles do not move at all.