Everyone you've ever met is from Earth. Unless you have something interesting to tell us. Earth is the prototype for terrestrial planets. It rotates fairly quickly. It consists of a mixture of rock and iron. Its interior is divided into layers, that is, differentiated. Like most terrestrial planets, Earth has a relatively thin atmosphere.Earth is also special in so many ways. It is the only place in the universe where we know life to exist. We have liquid water in our oceans and free oxygen in our atmosphere, which was not at breathable levels until just a few hundred million years ago. Earth also has plate tectonics, which which just might be essential to life. This animation shows how the crust of Earth has floated around over the last 750 million years. However, plate tectonics can have its downside as well. Sometimes the plates of Earth’s crust move quickly and violently. We call these events earthquakes. How common are earthquakes on Earth? Watch this animation. And what is happening right now?
Earth has a radius of 6378 km, across the equator, that is. From pole to pole it is about 21 km smaller. This flattening is an effect of Earth’s relatively quick rotation.
Earth rotates in 23 hours 56 minutes at the sidereal rate, referenced to the stars. Its synodic day, from noon to noon, is 24 hours . Our clocks keep time at the synodic rate,which keeps track of the Sun’s position in our sky
Earth revolves around the Sun in 365.24 days. It’s what we call a year. Since there is not an even number of days in one trip around the Sun, we have to add a day every four years. That’s what we call a leap year.
Earths atmosphere consists of about 80% nitrogen gas and 20% oxygen gas with some other trace gases. Our atmosphere is rather complicated with a number of different distinct layers.
Earths magnetic field is generated in the interior in the iron outer core.