The Solar System

30 PART 1^ |^ EXPLORING THE SKY

Learning to Look

1. Find Sagittarius and Scorpius in the photograph that opens this
   chapter.


2. The stamp below shows the constellation Orion. Explain why this looks
   odd to residents of the northern hemisphere.


3. Imagine that the diagram below is a photograph taken in mid-Septem-
   ber. Use the star charts at the back of this book to decide about what
   time of night the photo would have been taken.

Ursa

Minor

Ursa

Major

A few circumpolar

constellations

Polaris

Perseus

Cassiopeia

Rotation

of sky

Rotation

of sky

Cepheus

14. How Do We Know? How can a scientifi c model be useful if it isn’t a
    correct description of nature?


15. How Do We Know? In what way is astrology a pseudoscience?


16. How Do We Know? How is evidence a distinguishing characteristic
    of science?


17. How Do We Know? Why must a scientifi c argument dealing with
    some aspect of nature include all of the evidence?

Discussion Questions

1. All cultures on Earth named constellations. Why do you suppose this
   was such a common practice?


2. If you were lost at sea, you could fi nd your approximate latitude
   by measuring the altitude of Polaris. But Polaris isn’t exactly at the
   celestial pole. What else would you need to know to measure your
   latitude more accurately?


3. Do planets orbiting other stars have ecliptics? Could they have seasons?

Problems

1. Star A has a magnitude of 2.5; Star B, 5.5; and Star C, 9.5. Which is
   brightest? Which are visible to the unaided eye? Which pair of stars
   has an intensity ratio of 16?


2. If one star is 6.3 times brighter than another star, how many
   magnitudes brighter is it?


3. If light from one star is 40 times more intense than light from another
   star, what is their difference in magnitudes?


4. If two stars differ by 7 magnitudes, what is their intensity ratio?


5. If two stars differ by 8.6 magnitudes, what is their intensity ratio?


6. If star A is magnitude 4 and star B is magnitude 9.6, which is brighter
   and by what factor?


7. By what factor is the sun brighter than the full moon? (Hint: See
   Figure 2-6.)


8. What is the angular distance from the north celestial pole to the point
   on the sky called the summer solstice? To the winter solstice?


9. If you are at a latitude of 35 degrees north of Earth’s equator, what is
   the angular distance from the northern horizon up to the north celestial
   pole? From the southern horizon down to the south celestial pole?