Astro 121 Homework 2: Solar System and Eclipses, Assignments of Astronomy

Download Astro 121 Homework 2: Solar System and Eclipses and more Assignments Astronomy in PDF only on Docsity! Astro 121 HW#2 1/25/05 The Solar System: Homework #2 (due at the beginning of lecture, February 2) 1. (a) What is a lunar eclipse? (b) What is a solar eclipse? (c) What phases of the moon are associated with each type of eclipse and why? (d) Why can eclipses only occur during two “eclipse seasons” each year? (ignore the precession of the Moon’s orbit) 2. Imagine you see the Moon about 45o above the eastern horizon at sunset. (a) What is the phase of the Moon? Imagine you see the Moon setting in the west at noon. (b) What is the phase of the Moon? Imagine you see the Moon about 45o above the western horizon at sunrise. (c) What is the phase of the Moon? 3. Assume the Moon’s orbit is a perfect circle centered on the Earth. Through how many degrees, arc minutes and arc seconds does the Moon move in (a) one hour of time, (b) one day?, (d) How long does it take the Moon to move an angle on the sky equal to its own diameter? 4. Assuming circular orbits, (a) calculate the mean velocity of the Moon (in km/s and mph) in its orbit around the Earth using the mean Moon-Earth distance of 384,000km. (b) Compare this to the mean velocity of the Earth in its orbit around the Sun (in km/s and mph—Earth-Sun distance is 1.5x108km). 5. The Moon and the Sun have approximately the same angular diameter as seen from the Earth. Use the Earth-Moon and Earth-Sun distances from the problem above to calculate how many times larger the physical diameter of the Sun is than the Moon.