Ch 2 – The Earth’s Shape and its Movements

The earth is an oblate spheroid, not a sphere

What are the polar and equatorial circumferences?

The interior of the earth was studied and determined by the use of seismic waves.

The crust is the solid part around the edge of the earth. Can be 6 to 19 miles thick.

Below that is the mantle, divided into 2 regions: the lithosphere and the asthenosphere. Around 1800 miles thick.

Below that is the core, divided into 2 regions: the outer liquid core and the inner solid core. It is around 2000 miles thick.

The Earth generates a magnetic field.

The magnetic field protects us from much of the Sun’s radiation. That radiation also compresses the magnetosphere where it hits it.

That radiation creates the northern and southern lights seen at the poles.

The Earth also creates a large gravitational field.

Gravity, first explained by Issac Newton (the dude with the apple), depends on the mass of objects.

The more massive an object is, the more gravity it creates.

The gravitational pull between 2 objects depends on their masses and how close they are. The closer they are the stronger the pull.

The force generated by the pull of gravity is known as weight.

The further you get away from Earth, the less you weigh. The more mass you lose, the less you weigh.

The Earth is tilted at angle of 23.5 degrees relative to the Earth’s orbit around the sun.

The Earth spins at about 1000 mph and takes 23 hours, 56 minutes and 4 seconds to make 1 rotation.

The North Star is the only star in the sky that does not move during the night, since the North Pole points almost directly to it. Will this always be the case?

The Earth rotates around the Sun in an elliptical orbit at a speed of about 67000 mph.

It takes 365.24 days to make a revolution around the Sun. The .24 is why we need Leap Year.

The height of the sun during the day changes with the seasons.