The real facts about Earth

Earth is the third planet from the Sun and the fifth largest of the planet. Earth is the only planet whose English name does not originate from Greek/Roman mythology. The name derives from Old English and Germanic.

Earth, for sure, can be studied without the aid of spacecraft. However it was not until the twentieth century that we had maps of the complete planet. Pictures of the planet taken from space are of significant importance; for instance, they are a huge help in weather prediction and especially in tracking and predicting hurricanes. And they are amazingly beautiful. The Earth's magnetic field and its relations with the solar wind also generate the Van Allen emission belts, a pair of doughnut shaped rings of ionized gas (or plasma) trapped in orbit just about the Earth. The outer belt stretches from 19,000 km in altitude to 41,000 km; the inner belt lies involving 13,000 km and 7,600 km in altitude.

The Earth's surface is extremely young. In the relatively short (by astronomical standards) time of 500,000,000 years or so erosion and tectonic processes destroy and remake most of the Earth's surface and thus eliminate almost all traces of earlier geologic surface history (such as impact craters). Thus the very early on history of the Earth has mostly been erased. The Earth is 4.5 to 4.6 billion years old, but the oldest recognized rocks are about 4 billion years old and rocks older than 3 billion years are rare. The oldest fossils of existing organisms are less than 3.9 billion years old. There is no evidence of the critical period when life was first getting in progress.

The Earth's atmosphere is 77% nitrogen, 21% oxygen, with draws of argon, carbon dioxide and water. There was perhaps a very much larger amount of carbon dioxide in the Earth's atmosphere when the Earth was first created, but it has since been nearly all incorporated into carbonate rocks and to a smaller extent dissolved into the oceans and consumed by living plants. Plate tectonics and biological processes now keep a repeated flow of carbon dioxide from the atmosphere to these various "sinks" and back over again. The small amount of carbon dioxide occupant in the atmosphere at any time is very important to the maintenance of the Earth's surface temperature through the greenhouse effect. The greenhouse effect raises the average surface temperature regarding 35 degrees C above what it would if not be (from a frigid -21 C to a comfortable +14 C); without it the oceans would freeze and life as we know it would be impossible.