Astronomy Lecture Notes Day 07 Angular Size and the Apparent Motion of the Moon
1. Intro
a. Collect Homework and Exams
b. Note Study Guide for 2nd exam on Hot tips…more to be added
c. Homework due on Thursday – pay attention today and it will be a piece of cake.
d. You should be studying Units 8 (don’t concentrate on eclipses), 10.4, 11 & 12
2. Angular Size
a. Introduce the angular units of arcminutes and arc seconds.
b. Derive the angular size relation (Unit 10.4)
i. Caution: the angular size must be expressed in degrees
ii. Caution: D stands for distance not diameter
c. Practice the angular size relation with the handout
d. Assign the Angular size homework on Hot Tips
3. Apparent Motion of the Moon (Unit 8)
a. Diurnal Apparent Motion
i. Simulate diurnal motion with Starry Night
ii. Moon falls the behind the stars (east of the stars) by about 13 degrees per day or about 52 minutes
iii. So the Moon will rise about 52 minutes later each day – on average!
b. Monthly Apparent Motion
i. Demonstrate the Moon’s motion in relation to the ecliptic using Sky Gazer
ii. Illustrate the Moon’s sidereal period - 27.3 days
c. Using the Moon and Sun define planetary configurations of (Unit 11.3)
i. Opposition - opposite the Sun, 12 hr RA between the Sun and Moon
ii. Conjunction – together with the Sun, 0 hr RA between the Sun and Moon
iii. Quadrature – The Sun-Earth-Moon forms a 90 angle, 6 hours of RA between the Sun and Moon
d. Associate various phases of the Moon with those configurations
i. Full – opposition
ii. New – Conjunction
iii. 1st or 3rd Quarter – Quadrature
iv. Illustrate the Moon’s synodic period using Sky Gazer – 29½ days
v. During which season will the full moon be highest in the night sky for an observer in Syracuse,
NY?
4. Next Time
a. Lunar Phases
b. Apparent Motion of the Planets
c. Our place in the Universe based on the apparent motion of the stars, Sun, Moon and planets.