Astronomy Part 2
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
49.What causes the apparent retrograde motion of the planets?
As Earth passes another planet, the other planet appears to move backward with respect to the background stars, but the planet's motion does not actually change.
What is the basic reason that we have seasons on Earth?
Earth's axis is tilted relative to the ecliptic plane.
Where does the Sun remain above the horizon all day (never setting) on the December solstice?
Everywhere between the Antarctic Circle (latitude 66.5°S) and the South Pole
14.What makes the North Star, Polaris, special?
It appears very near the north celestial pole.
22.Which of the following statements about lunar phases is true?
It is possible to have two full Moons during January, but not usually during February.
What happens to Earth's axis as we orbit around the Sun over the course of each year?
It remains pointed in the same direction at all times.
What is special about the June solstice?
It's the day on which the Northern Hemisphere receives its most direct sunlight.
41.If part of the full Moon passes through Earth's umbra, we will see a(n)
partial lunar eclipse.
45.What is the Saros cycle?
the 18-year cycle over which the pattern of eclipses repeats
5.What is the ecliptic?
the Sun's apparent path along the celestial sphere
Which of the following statements are true about summer compared to winter?
*You have more daylight and less darkness in summer. *The Sun follows a longer and higher path through your sky in summer. *Temperatures tend to be warmer in summer.
The Sun reaches the zenith (directly overhead) at midday ___________.
*everywhere within the tropics (between latitudes 23.5°N and 23.5°S) on two dates each year *on the equator only on the March and September equinoxes
Rank the seasons for the Southern Hemisphere based on Earth's distance from the Sun when each season begins, from closest to farthest.
Summer, Fall, Spring, Winter
19.Why is it summer in the Northern Hemisphere when it is winter in the Southern Hemisphere?
The Northern Hemisphere is tilted toward the Sun and receives more direct sunlight.
52.Which of the following statements about stellar parallax is true?
The closer a star is to us, the more parallax it exhibits.
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.
39.What conditions are required for a lunar eclipse?
The phase of the Moon must be full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun.
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.
38.What conditions are required for a solar eclipse?
The phase of the Moon must be new, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun.
What is the cause of the seasons?
The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
How variation in the Earth-Sun distance affects the seasons?
The variation in Earth-Sun distance over the course of each year has virtually no effect on the seasons.
54.Why were ancient peoples unable to detect stellar parallax?
They did not have the ability to measure very small angles.
65.The Moon and the Sun are approximately the same angular size.
True
Rank the seasons for the Northern Hemisphere based on Earth's distance from the Sun when each season begins, from closest to farthest.
Winter, Spring, Fall, Summer
7. Which of the following correctly describes the meridian in your sky?
a half-circle extending from your horizon due north, through your zenith, to your horizon due south
2.Which of the following best describes the modern definition of a constellation?
a region of the celestial sphere
11.What is a circumpolar star?
a star that always remains above your horizon and appears to rotate around the celestial pole
32.Why do we see essentially the same face of the Moon at all times?
because the Moon's rotational and orbital periods are equal
25.If the Moon is setting at 6 A.M., the phase of the Moon must be
full
2.08If we have a new moon today, when we will have the next full moon?
in about 1 week in about 2 weeks
28.At approximately what time would a full Moon be on your meridian?
midnight
Suppose you live at a mid-latitude in the Southern Hemisphere (such as in Australia, New Zealand, Chile, or South Africa). When will you have 12 hours of daylight and 12 hours of darkness?
on both the March and September equinoxes
15.You are standing on Earth's equator. Which way is Polaris, the North star?
on the northern horizon
26.If the Moon is setting at noon, the phase of the Moon must be
third quarter.
43.When are eclipse seasons?
when the nodes of the Moon's orbit are nearly aligned with the Sun