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P32, Review & Discussion Questions
1. Earth = 1.5 x 104 km (aka…1/24th of a Light second)
Sun = 1.5 x 106 km (aka…4.5 light seconds…remember, 1 AU is 500 light seconds)
Milky Way = 1.0 x 1018 km (150,000 light-YEARS
Universe = 1.4 x 1024 km (13,700,000,000 LY)
2. The Universe = the totality of all space, time matter & energy
3. One light year = 9.4 x 1012 km
4. Sci. method is the classic five-step process used to learn about the universe. Religion
uses revealed scripture to explain phenomena whereas science relies on observation,
testing & peer review.
5. A constellation is an agreed upon arrangement of stars. They are VERY useful as
“land”marks in the sky
6. Because the Earth rotates once every 24 hours, all celestial objects rise in the east and set
in the west.
7. Because the earth orbits the sun solar day is about 4 minutes longer than a sidereal (“starbased”) day.
8. (Different for each person)
9. Because the sun appears to move slowly through constellations - the constellations that
are visible at night change as the sun moves along the ecliptic.
10.Because the earth’s rotational axis is tilted approx. 23.5 degrees, different areas of the
earth’s surface get differing amounts of sunlight throughout the year.
11.Precession is the “wobble” in the earth’s axis causing the celestial poles to wobble 360
deg through the sky once every 28000 years.
12.To accommodate imperfections in solar days and years.
13.We see phases of the moon because the side of the moon that is lit always faces the Sun,
but only fully faces earth during full moon.
14.Lunar eclipse occurs when the moon passes through the earth’s shadow. “S E m”
Solar eclipse occurs when moon passes between sun and earth, casting shadow “S m E”
(never m S E!!)
15.The moon’s orbit around the earth is slightly tilted compared to the earth’s orbit around
the sun (the two “loops” cross in only two places, and both earth and moon have to be at
the “cross” at the same time for an eclipse to occur)
16.If their moon is the same angular diameter as their star OR LARGER, YES. Otherwise
it’s called a transit.***
17.The apparent motion of a nearer object against a background as the observer’s position
changes.
18.The longer the baseline, the more accurate the measurement, and the objects being
measured are great distances away.
19.Baseline and parallax angle.
20.Would the constellations look different from different places in:
Solar system? No.
Nearest star? A couple stars near to the sun would shift noticeably, but the rest of
the stars would not appear to move much at all, certainly not enough to change
most constellations.
Galaxy? NO WAY. You couldn’t even SEE the stars in our night sky at all (the
galactic center is too far away!)
Think of it this way: If you’re standing next to a tree in the woods near school, would the
rest of the trees look different if you stood…
- 4” to either side? No.
- Next to a nearby tree? A couple trees near you would shift noticeably, but the
rest of the trees would not appear to move much at all, certainly not enough to
change the appearance of the rest of the forest.
- In a forest in Europe? (See what I mean?) 