HW#22: pg. 442 Rev 1 – 3; CST 1 – 3
Rev 1 – 3
1. How is parallax used to measure the distances to stars? What is a parsec?
2. Explain two ways in which a star's real motion through space translates into motion that is observable from Earth.
3. How do astronomers go about measuring stellar luminosities? What is the difference between luminosity and apparent brightness?
CST 1 – 3
1. If Earth's orbit around the Sun were smaller, the parallactic angle to the star shown in Figure 17.1 ("Stellar Parallax") would be (a) smaller; (b) larger; (c) the same.
2. From a distance of 1 parsec, the angular size of Earth's orbit would be (a) 1 degree; (b) 2 degrees; (c) 1 arc minute; (d) 2 arc seconds.
3. According to the inverse square law, if the distance to a lightbulb increases by a factor of 5, the bulb's apparent brightness (a) stays the same; (b) becomes 5 times less; (c) becomes 10 times less; (d) becomes 25 times less.