Chapter 2 Flashcards
Suppose that instead of being inclined to Earth’s orbit around the Sun, the Moon’s orbit was in the same plane as Earth’s orbit around the Sun. In this hypothetical situation, approximately how many solar eclipses would occur each year?
12
In reality, the Moon’s orbit about Earth is tilted (by about 5°) with respect to Earth’s orbit about the Sun. As a result, the actual number of solar eclipses that occur each year is approximately _____.
2
What conditions must exist for a solar eclipse to occur?
The phase of the Moon must be new and the Moon must be passing through Earth’s orbital plane.
What conditions must exist for a lunar eclipse to occur?
The phase of the Moon must be full and the Moon must be passing through Earth’s orbital plane.
If you could change the layout of the solar system, which of the following would cause a lunar eclipse to occur at least once every month in this hypothetical situation?
Change the Moon’s orbital plane so it is in the same plane as Earth’s orbit around the Sun.
Which of the following statements about the celestial sphere is NOT true?
The Earth is placed at the center of the celestial sphere.
The celestial sphere does not exist physically.
When we look in the sky, the stars all appear to be located on the celestial sphere.
The “celestial sphere” is another name for our universe.
The “celestial sphere” is another name for our universe.
The Andromeda Galaxy is faintly visible to the naked eye in the constellation Andromeda. Suppose instead it were located in the same direction in space as the center of the Milky Way Galaxy (but still at its current distance). How would it appear to the eye in that case?`
We could not see it at all.
An angle of 1 arcsecond is _________.
less than the thickness of a human hair held at arm’s length
When traveling north from the United States into Canada, you’ll see the North Star (Polaris) getting _________.
higher in the sky
Suppose you use the Southern Cross to determine that the south celestial pole appears 40 degrees above your horizon. Then you must be located at _________.
latitude 40 degrees south
Suppose you are facing north and you see the Big Dipper close to your northern horizon, with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours?
To the right of Polaris; that is, 90 degrees counterclockwise from its current position
In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because _________.
our evening view of space depends on where Earth is located in its orbit around the Sun
The Sun’s path, as viewed from the equator, is highest in the sky on _________.
the spring and fall equinoxes
Suppose Earth’s axis tilt was significantly greater than its current 23.5 degrees, but Earth’s rotation period and orbital period were unchanged. Which statement below would not be true?
The region of Earth where the Sun does not rise on the winter solstice would be larger (extending farther south) than it is now.
Polaris would not be our North star.
The length of each season (for example, the number of days from the summer solstice to the fall equinox) would be significantly longer than it is now.
Summers and winters would be more severe (for example, hotter and colder, respectively) than they are now.
The length of each season (for example, the number of days from the summer solstice to the fall equinox) would be significantly longer than it is now.
If our year were twice as long (that is, if Earth took twice as many days to complete each orbit around the Sun), but Earth’s rotation period and axis tilt were unchanged, then _________.
the four seasons would each be twice as long as they are now
How does Earth’s varying distance from the Sun affect our seasons?
It doesn’t — Earth’s orbital distance plays no significant role in the seasons.
Suppose you live in the United States and you see a crescent moon in your evening sky tonight. What will a friend in South America see tonight?
Your friend will also see a crescent moon.
Suppose it is full moon. What phase of Earth would someone on the Moon see at this time?
new Earth
It’s 6 am and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon’s phase?
third quarter
You observe a full moon rising at sunset. What will you see at midnight?
A full moon high in the sky
All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new moon?
The nodes of the moon’s orbit precess with an 18-year period.
The Moon goes through a complete cycle of phases about every 29 1/2 days.
The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane.
The Moon is only about 1/4 as large as Earth in diameter.
The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane
