One would have to come from outside the planet to discover Earth
. There has been no one so far who said that Earth was discovered by aliens. In fact, planet Earth has been in the universe for a long time before humans existed.
Earth is the third planet from the sun and was known by the Ancient Egyptians, Sumerians and the Greeks. Early humans thought that Earth was at the center of the universe and other planets, suns, stars and moons rotated around the Earth. The Earth was believed to be flat by the Arabs and Vikings.
Early astronomers faced few problems, they noticed that some planets did not move in a straight trail and some stopped while moved backwards. Ptolemy concluded that other planets orbited inside little spheres and these spheres rotated around Earth.
Nicolaus Copernicus proposed in the 16th century that Earth and the planets revolved around the sun instead. He had come up with a model of a solar system. His observations were based on Galileos model.
Some scientists from McGill University in Canada recently discovered the oldest rocks on the planet and their age would tell them how planet Earth began. The dug up rocks in Quebec were believed to be 4.28 billion years old. This suggests the age of the planet as 300 million years older.
The Earth is a strange and the only planet in the solar system having has an active plate tectonics. It brings up carbon rich plants from the bottom of the oceans and also has a green house effect when they shift.
The Earth is made up of mainly iron, silicon and oxygen. Heavy iron deposits are found at Earths core said to be up to 88%. The crust of the planet has 47% oxygen and 70% of the planet is covered with water.
The exact earth day lasts for 23 hours, 56 minutes and 4 seconds and one Earth day is called by astronomers as sidereal day. It is predicted that the further life of Earth is 5 billion years and it will turn into a burnt out planet along with the sun after that.