Question

1. earths axis of rotation is tilted at an angle of 23.5 degrees. what is one change you would see on earth if its axis was not tilted? (5 points)
2. when earth is closest to the sun, the northern hemisphere is in winter. (20 points)

a. why is this true? (10 points)
b. given the effects of precession, will this still be the case in 13,000 years? explain your answer. (10 points)

Explanation:

1. The tilt of Earth's axis is responsible for seasons. Without the tilt, there would be no seasonal changes as the amount of sunlight received at each latitude would remain relatively constant throughout the year.

4.A. Earth's seasons are not determined by its distance from the sun. Instead, they are due to the tilt of Earth's axis. When Earth is closest to the sun (perihelion), the Northern Hemisphere is in winter because of the tilt - the Northern Hemisphere is still receiving less direct sunlight despite the closer distance.
4.B. Precession is the slow, conical movement of Earth's axis. In about 13,000 years, the positions of the seasons relative to Earth's orbit will be reversed. So, in 13,000 years, when Earth is closest to the sun, the Northern Hemisphere will be in summer because precession will have changed the orientation of the tilt relative to the orbit.

Answer:

1. No seasonal changes.

4.A. Seasons are due to axis tilt, not distance from sun. When closest to sun, Northern Hemisphere tilt results in less direct sunlight and winter.
4.B. No. In 13,000 years, precession will reverse the seasons' position relative to orbit, so Northern Hemisphere will be in summer when Earth is closest to sun.