The interior of Earth is, of course, unexplored. However, we do have some sense of what goes on inside our
planet. The main layers of importance are the core, the mantle and the crust. We have not yet been able to drill
deep enough to reach the mantle of Earth, but one organization is close. Let's hope they don't make a Crack in the World.
The iron core of Earth generates an appreciable magnetic field around the planet. Charged particles from the Sun
stream outward in what is called the solar wind and are trapped in a region known as the Van Allen belts, after the University of
Iowa physicist who helped discover them last century. Here is a diagram of the Van Allen belts.
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 of our
planet in its iron outer core. In general, three things are
required in order for a planet to generate a magnetic field.
