Question

name:
date:
period:
latitude/polaris practice

1. what is the altitude of polaris here in mamaroneck (approx. 42°n)?
2. what happens to the altitude of polaris as you move north in the northern hemisphere?
3. what happens to the altitude of polaris as you move south in the northern hemisphere?
4. what happens to the altitude of polaris as you move due west from mamaroneck to chicago?
5. if the altitude of polaris in mamaroneck is 42° tonight, what will its altitude be tomorrow night?
6. how does polaris appear to change position during the night?
7. how do stars near polaris appear to change position during the night?
8. what is the altitude of polaris at the north pole?
9. what is the altitude of polaris at the equator?

10.if you cannot see polaris on a clear night, state something concerning your position on the earths surface?
11.if you are facing polaris, which compass direction is at your back?
12.if you are facing polaris, which compass direction is to your left?
13.where on earths surface is gravity the strongest?
14.where on earths surface is your weight the maximum?
15.as you move north in the northern hemisphere, what happens to your weight?

Explanation:

1. The altitude of Polaris is equal to the observer's latitude in the Northern Hemisphere. So, if the latitude is \(42^{\circ}N\), the altitude of Polaris is \(42^{\circ}\).
2. As you move north in the Northern Hemisphere, your latitude increases. Since the altitude of Polaris equals latitude, the altitude of Polaris increases.
3. As you move south in the Northern Hemisphere, your latitude decreases. Since the altitude of Polaris equals latitude, the altitude of Polaris decreases.
4. Moving due - west (or due - east) does not change your latitude. Since the altitude of Polaris equals latitude, the altitude of Polaris remains the same.
5. The altitude of Polaris at a fixed location (in the Northern Hemisphere) does not change from night to night (on a human - time scale, ignoring very long - term astronomical changes like precession). So it will still be \(42^{\circ}\).
6. Polaris is very close to the North Celestial Pole. Due to the Earth's rotation, it appears to have almost no apparent motion during the night.
7. Stars near Polaris appear to move in circular paths (counter - clockwise) around Polaris because of the Earth's rotation about its axis.
8. At the North Pole (\(90^{\circ}N\)), the altitude of Polaris is \(90^{\circ}\) (it is directly overhead).
9. At the equator (\(0^{\circ}\) latitude), the altitude of Polaris is \(0^{\circ}\) (it is on the horizon).
10. If you cannot see Polaris on a clear night, you are in the Southern Hemisphere (because Polaris is not visible from the Southern Hemisphere for practical purposes).
11. If you are facing Polaris (which is in the North), the direction at your back is South.
12. If you are facing Polaris (North), using the standard compass directions (assuming a flat - Earth, simple - direction model for this basic question), the direction to your left is West.
13. Gravity is strongest at the poles (because the Earth is an oblate spheroid; the polar radius is smaller than the equatorial radius, and \(g=\frac{GM}{r^{2}}\), where \(r\) is the distance from the center of the Earth. A smaller \(r\) (at the poles) gives a larger \(g\) value, also considering the effect of centrifugal force which is zero at the poles).
14. Your weight (\(W = mg\)) is maximum at the poles because \(g\) is maximum at the poles.
15. As you move north in the Northern Hemisphere, \(g\) increases (for the reasons mentioned in question 13). Since \(W=mg\) (\(m\) is constant for a person), your weight increases.

Answer:

1. \(42^{\circ}\)
2. The altitude of Polaris increases.
3. The altitude of Polaris decreases.
4. The altitude of Polaris remains the same.
5. \(42^{\circ}\)
6. It appears to have almost no apparent motion.
7. They appear to move in circular paths (counter - clockwise) around Polaris.
8. \(90^{\circ}\)
9. \(0^{\circ}\)
10. You are in the Southern Hemisphere.
11. South
12. West
13. At the poles
14. At the poles
15. Your weight increases.