Earths Rotation, Seasons, Precession and Nutation

Earths Rotation, Seasons, Precession and Nutation

Mr. Mendoza

What causes the day and night cycle?

Earth’s axis is the imaginary line that goes through the N & S poles.

Day and night are caused by the rotation of Earth on its axis - spinning towards & away from the Sun. (23.9345 hrs)

When the Sun “rises” …we are actually spinning TOWARDS it

When the Sun “sets” …we are actually spinning AWAY FROM it

Multiple Choice

Which term describes when the Earth spins on its axis.

• Rotation

• Revolution

• Kepler's Laws

• Precession

Multiple Choice

Which type of motion causes night / day?

• Rotation

• Revolution

• Kepler's 1st Law

• Nutation

Why are there 24 hours in a day?

There 24 hours in a day because...

Earth spins 15 degrees each hour There are 360 degrees in a circle (the circumference of Earth).

360 divided by 15 is 24 so there are 24 hours in a day!

What causes the seasons?

Seasons are caused by...

The tilt of the Earth on its axis as it revolves around (orbits) the Sun.

Earth's Orbit and Seasons

The tilt of Earth’s axis relative to the ecliptic is 23.5 degrees

Summer

What causes summer in the northern and southern hemispheres?

When the hemisphere is tilted toward the Sun during Earth’s orbit

Winter

What causes winter in the northern and southern hemispheres?

When the hemisphere is tilted away from the Sun during Earth’s orbit

Fun Fact

The seasons in the northern and southern hemispheres are opposite each other because when 1 hemisphere is tilted towards the Sun, the other is tilted away from it

Changes in The Seasons – 

Precession and Nutation

https://www.youtube.com/watch?v=qlVgEoZDjok

Multiple Choice

Wobbling around the processional axis

• Revolution

• Tide

• Nutation

• Universe

Multiple Choice

What is the circular offset of Earth’s position due to its rotation on its axis?

• Precession

• Nutation

• Barycenter

• Rotation