summary from the source i went and summarized the source in my own words science shows that the earth formed around billion years ago the organisms that live on earth have completely changed its air atmosphere this is called a biosphere of earth's surface is covered in salt water oceans earth is the only place in the solar system where liquid water is known to exist at present the other is made of rocky land in the shape of continents and islands earth interacts with other objects in the solar system particularly the sun and the moon the earth orbits or goes around the sun roughly once every days one spin is called a day and one orbit around the sun is called a year this is why there are days in a year but a leap day is added once every years it'd be great if someone could add that for me i have a rocket to catch bye for now