Astronomy Chapter 3 Review
Terms in this set (21)
The moon orbits in what direction?
It orbits Eastward around Earth once a month.
The same side of the moon always faces the Earth.
How many degrees is the moons orbit tipped?
The moon's orbit is tipped 5 degrees from the plane of Earth's orbit; the moon's path takes it slightly north then slightly south, but always somewhere near the ecliptic.
What is sidereal period?
Its the amount of time the moon takes to complete one exact revolution around Earth.
The sidereal period is 27 days.
What is the synodic period?
Its the amount of time it takes for the moon to go through one complete cycle of lunar phases; the synodic period is about 29.5 days.
Why is the synodic period longer than the sidereal period?
It takes time for the moon to catch up with the revolving Earth.
What is a Lunar Eclipse?
Occurs if a full moon passes through Earth's shadow and sunlight is cut off.
What is a Total Lunar Eclipse?
Occurs if the moon fully enters the dark umbra of Earth's shadow.
What is a Partial Lunar Eclipse?
Occurs if it only grazes the umbra
What is a Penumbral Lunar Eclipse?
Occurs if the moon enter the partial shadow of the penumbra.
What happens in totality?
The Eclipsed moon looks copper-red because of sunlight refracted through Earth's atmosphere.
Observers inside the path of totality can see total solar eclipse.
Those outside can see a partial solar eclipse.
What is a Solar Eclipse?
Occurs if a new moon passes between the sun and Earth.
Refers to how large an object appears in the sky, and depends on the distance to the celestial object and the linear diameter of the celestial object.
The moons closest point in orbit.
1.If you looked back at Earth from the moon, what phase would Earth have when the moon was full? New? First quarter? Waxing crescent?
moon: full, new, first, waxing
earth: new, full, third, waning
2. If a planet has a moon, must that moon go through the same phases that Earth's moon displays?
No, because the moon may be positioned differently
3.Could a solar-powered spacecraft generate electricity while passing through Earth's umbral shadow?
Through Earth's penumbral shadow?
Umbral: No, completely dark, no sunlight
Penumbral: yes, part of the sun is still visible which means it can get SOME energy from the little light
4. Why do solar eclipses happen only at new moon?
Can only occur if the moon passes a node near New Moon.
5. Identify the phases of the moon if on March 20 the moon is located at the point on the ecliptic called
(a) the vernal equinox,
(b) autumnal equinox,
(c) summer solstice,
(d) winter solstice.
6. About how many days must elapse between first-quarter moon and third-quarter moon?
7. How many times larger than the moon is the diameter of Earth' umbral shadow at the moon's distance?
8. The photo on pg. 48 shows the annular eclipse of May 30, 1984. How is it different from the annular eclipse shown in Figure 3-9?