Astronomy 115

Homework Assignment #2

Due Date:

For all homework assignments, write neatly, staple multiple pages, and show your work, where appropriate. Do not turn in this page with the homework.

  1. Pick two of the lunar phases from the list below and for each, draw the arrangement of the Sun, Earth and Moon. Also draw what the Moon would look like during that phase. (Phases to chose from are: Waxing Crescent, First Quarter, Waxing Gibbous, Waning Gibbous, Third Quarter, Waning Crescent and New.)

  2. In your own words describe why Lunar Eclipses occur.

  3. How did Ptolemy explain the retrograde motions of the planets?

  4. What causes retrograde motions of the planets, according to the Heliocentric Theory?

  5. Chapter 2, "What if..." Question 29

  6. Why do scientists now accept the Heliocentric Theory of the Solar System? What evidence supports it, and disproves the Geocentric theory?

  7. What is special about the position and speed of the Earth when it is at perihelion? Which law or theory tells us this?

  8. Suppose a new asteroid was recently discovered which takes 557 months to orbit the Sun once (that's equal to 16,700 days or 46.4 years.). What is its average distance from the Sun? (Show your work.)

  9. The wavelength of red light is about 700 nm: λred = 700 nm.

    Which is larger, a grain of sand (diameter roughly 0.2 mm) or a wave of red light? How many times larger?

    NOTE: see "Astro Lingo" sheet for measurement units & conversions

  10. Which types of electromagnetic radiation from space pass through Earth's atmosphere to reach the ground?