Introduction to Astronomy

Q1:length of solar day Q2: far side of moon Q3: Phase, location, time Q4: Eclipses
Lecture slides

Time Scales

Back in the day, the POINT of astronomy was to tell time. Not necessarily the time of day, but the time of year, or how many years had passed since so-and-so was king. There are 4 interesting time scales that govern the overall appearance of the sky: 26,000 years, one year, one month, one day. We'll talk about the min order of shortest to longest, but be aware that a fraction whatever happens over the course of a month also happens over a day!
These time scales are all due to the fact that the Earth and Moon move over time, both through space and around their own axes.

Concept Question 1:
If the Earth orbited the Sun twice as fast as it does now (1 orbit=182.5 days), what would be the length of the SOLAR day?

  1. 23 h 56 m
  2. 48 h
  3. 12 h
  4. 24 h 4 m

Concept Question 2:
If the moon rotated around its own axis half as fast as it does now, we would still never see the 'far' side.

  1. T
  2. F

Concept Question 3:
You observe the first quarter moon on the Eastern horizon. What time is it?

  1. midnight
  2. 6 am
  3. noon
  4. 6 pm

Concept Question 4:
Solar eclipses occur because

  1. the shadow of the Earth falls on the Sun.
  2. the shadow of the Moon falls on the Earth.
  3. The shadow of the Moon falls on the Sun.
  4. The shadow of the Sun falls on the Earth.