Reference no: EM13856856

1. Describe the difference between a solar day and a sidereal day, and state why they are different. Use a diagram to explain your answer.

2. Explain why it is convenient to have the Earth divided into time zones, rather than using local solar time at every location.

3. A constellation is a grouping of stars that appear near each other in the sky when viewed from Earth. Are the stars in a constellation all the same distance from us? Explain.

4. Explain how our seasons would be different if the Earth's axis were not tilted (that is, if the axis were perpendicular to the Earth's orbital plane). What would the seasons be like if the Earth's axis were tipped 90º instead of 23½º?

5. Our calendar, like many ancient ones, has the year divided into months that are based on the motions of the Moon. Is the sidereal month or the lunar month used in these calendars? Explain.

6. Explain why, on certain nights, the Moon is never visible at all.

7. If a quarter Moon is already up when the Sun sets, is it first or third quarter? Use a diagram to explain your answer.

8. What is the Moon's phase if it is at the zenith at 10am? What is the Moon's phase if it is rising at 10am? What is the Moon's phase if it is setting at 10am? Use a diagram to explain your answers.

PROBLEMS - Show your work

1. How fast, in miles per hour, does a point on the Earth's equator travel due to the Earth's rotation? Use 12,742 km for the diameter of the Earth and 1 mi = 1.6 km.

2. The difference between a solar day and a sidereal day is 3m56s. Over the course of 1 year, how many days does this difference amount to? Discuss the significance of your answer.

3. Due to precession, the celestial poles shift position relative to the stars, undergoing a full cycle in 26,000 years. Each celestial pole travels over a circular path on the sky during this time. How far, in degrees per year, do the celestial poles shift in one year?

4. The Mauna Kea Observatory in Hawaii lies at a latitude of roughly 20ºN, and the declination of the Magellanic Clouds is about -70º. Can the Magellanic Clouds be observed from Mauna Kea? Explain.

5. Suppose you're located at a latitude of 30ºN. Find how far the Sun is above the nearest horizon (northern or southern) at noon on the day of the northern winter solstice, and state which horizon is closest to the Sun at this time.

6. Suppose you're located at a latitude of -10° (or 10° S). Find how far the Sun is above the nearest horizon (northern or southern) at noon on the day of the southern summer solstice, and state which horizon is closest to the Sun at this time.

7. Our calendar contains exactly 365 days instead of the more accurate 365.242 days. How long does it take for an error of one full day to accumulate? How is this time related to the leap year that we observe every four years?