Roughly 71 percent of Earth's surface is covered by water, most of it in the oceans. About a fifth of Earth's atmosphere is made up of oxygen, produced by plants. While scientists have been studying our planet for centuries, much has been learned in recent decades by studying pictures of Earth from space. Hope that helps :)
The moon orbits the Earth and the Earth orbits the Sun. The gravity of the moon and the sun both tug on the water which impacts how extreme tides are during different parts of the year.
