Astronomy Exam 1: Online Questions Part 1
What conditions must exist for a lunar eclipse to occur? Select all that apply. View Available Hint(s) it must be full moon the Moon must be passing through Earth's orbital plane it must be new moon it must be near the time of the summer or winter solstice the Moon must be below Earth's orbital plane
1, 2
Which of the following statements about phases of the Moon are true? Select all that apply. 1. at new moon, the half of the Moon facing the Sun is fully illuminated 2. at new moon, the Moon's entire surface is engulfed in darkness 3. at new moon, we see only the "night" side of the Moon 4. if it is full moon, the Moon will rise around sunset 5. if it's new moon, the Moon will rise in the middle of the day 6. the time between first-quarter moon and third-quarter moon is about a month 7. the time between new moon and full moon is about two weeks
1, 3, 4, 7
What do astronomers mean by a constellation? a. A constellation is a region in the sky as seen from Earth. b. A constellation is a group of stars related through an ancient story. c. A constellation is any random grouping of stars in the sky. d. A constellation is a group of stars that are all located in about the same place in space.
a. A constellation is a region in the sky as seen from Earth
About how many stars are visible to the naked eye on a clear, dark night away from city lights? a. a couple thousand b. a few hundred billion c. a few dozen d. several million
a. a couple thousand
Lunar eclipses can occur only during a _________. View Available Hint(s) a. new moon b. full moon c. third-quarter moon d. first-quarter moon
b
Suppose it is full Moon. What phase of Earth would someone on the Moon see at this time? View Available Hint(s) a. full Earth b. new Earth c. Earth does not go through phases as seen from the Moon. d. first-quarter Earth
b
What conditions must exist for a solar eclipse to occur? View Available Hint(s) a. The only condition is that the phase of the Moon must be new. b. The phase of the Moon must be new and the Moon must be passing through Earth's orbital plane. c. The only condition is that the phase of the Moon must be full. d. The phase of the Moon must be full and the Moon must be passing through Earth's orbital plane.
b
At most times, Mars appears to move __________ relative to the stars. The exceptions are during its periods of apparent retrograde motion, when Mars appears to move _________ relative to the stars.
eastward, westward
Kepler's first law states that the orbit of each planet is an ellipse with the Sun at one focus. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's first law? Check all that apply. View Available Hint(s) 1. Venus orbits the Sun faster than Earth orbits the Sun. 2. Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. 3. The Sun is located slightly off-center from the middle of each planet's orbit. 4. All the planets orbit the Sun in nearly the same plane. 5. Earth is slightly closer to the Sun on one side of its orbit than on the other side. 6. Inner planets orbit the Sun at higher speed than outer planets.
3, 5
Based on their inability to detect stellar parallax, the ancient Greeks concluded that _________. View Available Hint(s) 1. they lacked the technology necessary for detecting stellar parallax 2. the stars must be extremely far away 3. Earth must be the center of the universe 4. either Earth is the center of the universe or stars are extremely far away
4
What conditions must exist for a solar eclipse to occur? Select all that apply. View Available Hint(s) the Moon must be above Earth's orbital plane it must be near the time of the spring or fall equinox it must be full moon it must be new moon the Moon must be passing through Earth's orbital plane
4, 5
A waxing gibbous moon rises at about 3pm, reaches its highest point in the sky at about 9pm, and sets around 3am. A first quarter moon rises at about noon, reaches its highest point in the sky at about sunset, and sets around midnight. A waxing crescent moon rises at about 9am, reaches its highest point in the sky at about 3pm, and sets around 9pm. A full moon rises at about sunset, reaches its highest point in the sky at midnight, and sets around sunrise. A new moon rises at about sunrise, reaches its highest point in the sky at about noon, and sets around sunset. A waning gibbous moon rises at about 9pm, reaches its highest point in the sky at about 3am, and sets around 9am.
A waxing gibbous moon rises at about 3pm, reaches its highest point in the sky at about 9pm, and sets around 3am. A first quarter moon rises at about noon, reaches its highest point in the sky at about sunset, and sets around midnight. A waxing crescent moon rises at about 9am, reaches its highest point in the sky at about 3pm, and sets around 9pm. A full moon rises at about sunset, reaches its highest point in the sky at midnight, and sets around sunrise. A new moon rises at about sunrise, reaches its highest point in the sky at about noon, and sets around sunset. A waning gibbous moon rises at about 9pm, reaches its highest point in the sky at about 3am, and sets around 9am.
Which of the following can you observe about Venus with the naked eye? Select all that apply. 1. Venus sometimes shines brightly in the western sky shortly after sunset 2. When Venus is brightest, it is visible all night long 3. Venus sometimes shines brightly in the eastern sky shortly before dawn 4. Venus is visible at midnight when it is in its full phase
1, 3
Which of the following statements are true about summer compared to winter? Select all that apply. 1. You have more daylight and less darkness in summer. 2. At a given time of day, shadows are longer in summer. 3. Temperatures tend to be warmer in summer. 4. The Sun follows a longer and higher path through your sky in summer.
1, 3, 4
Kepler's third law states that a planet's orbital period, p, is related to its average (semimajor axis) orbital distance, a, according to the mathematical relationship p2=a3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's third law? Check all that apply. View Available Hint(s) 1. Inner planets orbit the Sun at higher speed than outer planets. 2. All the planets orbit the Sun in nearly the same plane. 3. Earth is slightly closer to the Sun on one side of its orbit than on the other side. 4. The Sun is located slightly off-center from the middle of each planet's orbit. 5. Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. 6. Venus orbits the Sun faster than Earth orbits the Sun.
1, 6
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. (Click "Show Moon with flat orbit" to see this situation.) In this hypothetical situation, approximately how many solar eclipses would occur each year? View Available Hint(s) 0 1 2 12 24
12
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? View Available Hint(s) 0 1 2 12 24
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 _____. 0 1 2 12 24
2
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 _____. View Available Hint(s) 0 2 12 24
2
Kepler's second law states that as a planet orbits the Sun, it sweeps out equal areas in equal times. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's second law? Check all that apply. View Available Hint(s) 1. The Sun is located slightly off-center from the middle of each planet's orbit. 2. Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. 3. All the planets orbit the Sun in nearly the same plane. 4. Venus orbits the Sun faster than Earth orbits the Sun. 5. Inner planets orbit the Sun at higher speed than outer planets. 6. Earth is slightly closer to the Sun on one side of its orbit than on the other side.
2
The Sun reaches the zenith (directly overhead) at midday ___________. Select all the options that make the statement true. 1. on the Arctic circle (66.5°N) on the June solstice 2. on the equator only on the March and September equinoxes 3. everywhere in the Northern Hemisphere on the June solstice 4. everywhere within the tropics (between latitudes 23.5°N and 23.5°S) on two dates each year 5. everywhere in the Southern Hemisphere on the December solstice 6. on the equator every day
2, 4
the dark, central region of an object's shadow, in which light from the Sun is fully blocked
Full shadow (umbra)
All of the following statements are true. Which one can be explained by Kepler's second law? a. Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun. b. Venus orbits the Sun at a faster orbital speed than Earth. c. All the planets orbit the Sun in nearly the same plane. d. Earth is slightly closer to the Sun in January than in July. e. The Sun is not in the precise center of Saturn's orbit.
a
How does Earth's varying distance from the Sun affect our seasons? View Available Hint(s) a. It doesn't; Earth's orbital distance plays no significant role in the seasons. b. It is responsible for the fact that the seasons are opposite in the Northern and Southern hemispheres. c. It makes summer warmer in the Northern Hemisphere than in the Southern Hemisphere. d. It causes the seasons to be more extreme than they would be if the Earth's distance from the Sun were always the same.
a
In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because _________. View Available Hint(s) a. our evening view of space depends on where Earth is located in its orbit around the Sun b. on any particular night, we can only see stars that are directly opposite (180 degrees away from) the Sun in the sky c. some constellations are circumpolar d. during some times of year, some constellations drop below the southern horizon
a
Jupiter orbits the Sun at an average distance of 5.203 AU and takes 11.86years to complete each orbit. Based on these facts, which statement is true? a. 11.862=5.2033 b. Jupiter's orbital period is 5.2033 times Earth's orbital period. c. 5.2032=11.863 d. Jupiter's orbital period is 5.2032 times Earth's orbital period.
a
All of the following statements are true. Which one can be explained by Kepler's third law? a. Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun. b. Venus orbits the Sun at a faster orbital speed than Earth. c. The Sun is not in the precise center of Saturn's orbit. d. All the planets orbit the Sun in nearly the same plane. e. Earth is slightly closer to the Sun in January than in July.
b
Based on what you have learned from your rankings in Parts A and B, which statement best describes how variation in the Earth-Sun distance affects the seasons? a. Summer occurs when Earth is closer to the Sun and winter occurs when Earth is farther from the Sun. b. The variation in Earth-Sun distance over the course of each year has virtually no effect on the seasons. c. No matter where you live or what the seasons, it is generally hotter when Earth is closer to the Sun and colder when Earth is farther from the Sun.
b
During the time that a planet is in its period of apparent retrograde motion: _________ View Available Hint(s) a. The planet appears to rise in the west and set in the east, rather than the usual rising in the east and setting in the west. b. Over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars c. The planet moves backwards (clockwise as viewed from above Earth's north pole) in its orbit of the Sun. d. The planet is getting closer to the Sun in its orbit.
b
Earth is slightly closer to the Sun in January than in July. How does the area swept out by Earth's orbit around the Sun during the 31 days of January compare to the area swept out during the 31 days of July? The area swept out in July is larger. Both areas are the same. The area swept out in January is larger.
b
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 _________. View Available Hint(s) a. stars would take twice as long to rise and set b. the four seasons would each be twice as long as they are now c. the cycle of precession would take 13,000 years instead of 26,000 years d. the Earth would not have seasons
b
If you are located in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location? View Available Hint(s) a. The altitude of the north celestial pole equals your longitude. b. The altitude of the north celestial pole equals your latitude. c. The altitude of the celestial equator equals your latitude. d. The longitude of the north celestial pole is circumpolar, and therefore crosses your zenith at the meridian.
b
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? View Available Hint(s) a. Summers and winters would be more severe (for example, hotter and colder, respectively) than they are now. b. 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. c. Polaris would not be our North star. d. The region of Earth where the Sun does not rise on the winter solstice would be larger (extending farther south) than it is now.
b
Suppose you see a photo showing Jupiter half in sunlight and half in shadow (that is, a first-quarter Jupiter). This photo might have been taken by _________. View Available Hint(s) a. the Arecibo radio telescope in Puerto Rico b. the Galileo spacecraft that orbited Jupiter in the 1990s c. the Keck telescope on Mauna Kea, Hawaii d. the Hubble Space Telescope (which orbits Earth)
b
The Moon always shows nearly the same face to Earth because ________. View Available Hint(s) a. the Moon does not rotate b. the Moon rotates once in the same amount of time that it takes the Moon to orbit Earth once c. the Moon rotates once in the same amount of time that it takes Earth to orbit the Sun once d. sunlight always hits the same face of the Moon
b
What is the basic reason that we have seasons on Earth? a. The amount of energy put out by the Sun varies over the course of each year. b. Earth's axis is tilted relative to the ecliptic plane. c. Earth's distance from the Sun varies over the course of each year. d. Earth's orbit is not quite a perfect circle.
b
What is the saros cycle? View Available Hint(s) a. The 26,000-year cycle of the Earth's precession b. The roughly 18-year cycle over which the pattern of eclipses repeats c. The annual cycle of the seasons d. The roughly one-month cycle of lunar phases in the sky
b
When is the next opportunity to see a total solar eclipse in the United States? December 4, 2021 April 8, 2024 at the next full moon at the next new moon August 12, 2026
b
Which of the following planets has essentially no seasons at all? View Available Hint(s) Neptune (axis tilt = 29.6°) Jupiter (axis tilt = 3.1°) Uranus (axis tilt = 97.9°) Mars (axis tilt = 25.2°)
b
hich of the following best describes why we have seasons on Earth? View Available Hint(s) a. The varying speed of Earth in its orbit around the Sun gives us summer when we are moving fastest and winter when we are moving slowest. b. The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year. c. Earth's elliptical orbit means we are closer to the Sun and therefore receive more intense sunlight at some times of year than at others. d. The tilt of Earth's axis causes the Northern Hemisphere to be closer to the Sun than the Southern Hemisphere in summer, and visa versa in winter.
b
A total solar eclipse can only happen during what lunar phase? a. waning gibbous b. new c. full d. first quarter
b. new
Consider a time when Mars is in the middle of one of its periods of apparent retrograde motion. During this time, Mars appears ________ in our night sky and crosses the meridian around _________.
brightest, midnight
During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space? View Available Hint(s) a. Mars is moving around the Sun in the opposite direction from which Earth is moving around the Sun. b. Earth and Mars are getting closer together. c. Earth is catching up with and passing by Mars in their respective orbits. d. Earth and Mars are on opposite sides of the Sun.
c
In Ptolemy's Earth-centered model, when would Venus appear directly behind the Sun as viewed from Earth? when it is in a crescent phase when it is in closest to Earth never when it is in farthest from Earth
c
It's 6 a.m. and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase? View Available Hint(s) a. full b. first quarter c. third quarter d. new
c
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 _________. View Available Hint(s) a. latitude 40 degrees north b. longitude 40 degrees c. latitude 40 degrees south d. latitude 50 degrees south
c
The point directly over your head is called _________. View Available Hint(s) a. the North Star b. the north celestial pole c. the zenith d. the meridian
c
What do we mean when we talk about the Milky Way in our sky? a. The whitish patch of light we see when we look toward the center of the Milky Way Galaxy. b. The spiral-shaped galaxy in which we live. c. The patchy band of light that outlines the plane of the Milky Way Galaxy as seen from Earth. d. The bright stars of the constellations that lie along the ecliptic in our sky.
c
What happens to Earth's axis as we orbit around the Sun over the course of each year? a. It sweeps out a cone while remaining at a 23½° tilt, so that it sometimes points toward Polaris and sometimes toward other stars. b. It wobbles back and forth, so that the tilt varies between 0° and 23½°. c. It remains pointed in the same direction at all times.
c
What is an annular eclipse? a. a type of eclipse that happens once each year b. a solar eclipse in which totality lasts for more than 2 minutes c. a solar eclipse in which the Moon does not appear large enough to fully block the Sun d. a lunar eclipse in which the Moon passes only through Earth's penumbra e. a lunar eclipse in which the Moon turns an eerie red color
c
What is special about the June solstice? a. It's the day when the Sun has the longest and highest path through the Southern Hemisphere sky. b. It's the day when Earth has the greatest axis tilt. c. It's the day on which the Northern Hemisphere receives its most direct sunlight. d. It's the longest day of the year for everyone on Earth.
c
What is the celestial sphere? a. The celestial sphere is a model that shows the true locations in space of the Sun and a few thousand of the nearest stars. b. It represents a belief in an Earth-centered universe, and hence is no longer considered to have any use. c. The celestial sphere is a representation of how the entire sky looks as seen from Earth. d. The celestial sphere is a model of how the stars are arranged in the sky relative to our Sun, which is in the middle of the sphere.
c
What is the ecliptic? a. The Sun's daily path from east to west in our sky b. The path traced by the Moon's shadow on Earth during a solar eclipse c. The path the Sun appears to trace around the celestial sphere each year d. A half-circle extending from your horizon due north, through your zenith, to your horizon due south
c
When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting _________. View Available Hint(s) a. dimmer b. lower in the sky c. higher in the sky d. brighter
c
Which of the following correctly describes the meridian in your local sky? View Available Hint(s) a. The point directly over your head b. A half-circle extending from your horizon due east, through the north celestial pole, to your horizon due west c. A half-circle extending from your horizon due north, through your zenith, to your horizon due south d. A half-circle extending from your horizon due east, through your zenith, to your horizon due west
c
Which of the following planets should have the most extreme seasons? View Available Hint(s) Neptune (axis tilt = 29.6°) Jupiter (axis tilt = 3.1°) Uranus (axis tilt = 97.9°) Mars (axis tilt = 25.2°)
c
You observe a full Moon rising at sunset. What will you see at midnight? View Available Hint(s) a. A third-quarter moon b. A waning gibbous moon c. A full moon high in the sky d. A first-quarter moon
c
You've now seen that Earth's varying distance cannot be the cause of our seasons. So what is the cause of the seasons? View Available Hint(s) a. The seasons are caused by variation in the amount of rainfall (or snowfall) in different places at different times of year. b. Earth's speed varies in its orbit around the Sun, giving us summer when Earth is moving fastest and winter when Earth is moving slowest. c. The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year. d. The tilt of Earth's axis causes the Northern Hemisphere to be closer to the Sun than the Southern Hemisphere in summer, and vice versa in winter.
c
All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new moon? View Available Hint(s) a. The nodes of the moon's orbit precess with an 18-year period. b. The Moon is only about one fourth as large as Earth in diameter. c. The Moon goes through a complete cycle of phases about every 29 1/2 days. d. The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane.
d
As you saw in Part C, stellar parallax exists only because Earth orbits the Sun. Therefore, if the ancient Greeks had measured stellar parallax, they would have known that their belief in an Earth-centered universe was wrong. Why didn't the ancient Greeks measure stellar parallax? View Available Hint(s) a. Some Greeks actually did measure it, but they did not understand the importance of their measurements. b. The Greeks thought all the stars were the same distance away, residing on a celestial sphere. c. Their belief in an Earth-centered universe meant that they did not expect parallax, and therefore did not look for it. d. Even for the nearest stars, parallax angles are too small to measure with the naked eye.
d
Each choice describes how a few astronomical phenomena are related to time periods. Which list is entirely correct? (Careful: some lists are partially correct.) View Available Hint(s) a. Earth's rotation defines a day. The saros cycle of eclipses defines a month. Earth's orbit defines a year. Earth's cycle of axis precession takes 26,000 years. b. Earth's rotation defines a day. The Sun's rotation defines a week. The Moon's rotation defines a month. Earth's orbit defines a year. c. Earth's rotation defines a day. The cycle of the Moon's phases takes about a week. Earth's orbit defines a year. Earth's cycle of axis precession defines a month. d. Earth's rotation defines a day. The cycle of the Moon's phases takes about a month. Earth's orbit defines a year. Earth's cycle of axis precession takes 26,000 years.
d
For most of history, the lack of observable stellar parallax was interpreted to mean that _________. View Available Hint(s) a. stars were too far away for parallax to be measured with available technology b. stars must all lie at the same distance from Earth, on the celestial sphere c. Galileo's theories of the universe were essentially correct d. Earth is stationary at the center of the universe Previous Answers
d
If we have a new moon today, when we will have the next full moon? View Available Hint(s) a. In about one week b. In about six months c. In about a month d. In about two weeks
d
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? View Available Hint(s) a. Make the Moon orbit Earth twice as fast. b. Change the Moon's orbital plane so it tilts the opposite way. c. Relocate the Moon to twice its current distance from Earth. d. Change the Moon's orbital plane so it is in the same plane as Earth's orbit around the Sun.
d
Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called _________. View Available Hint(s) a. seasonal b. bright c. celestial d. circumpolar
d
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? View Available Hint(s) a. Still in the same place, below Polaris b. Directly above Polaris c. To the left of Polaris; that is, 90 degrees clockwise from its current position d. To the right of Polaris; that is, 90 degrees counterclockwise from its current position
d
Suppose you see a moon that is half bright and half dark in your early evening sky. Then you are seeing a __________ moon. new third quarter full first quarter
d
The Sun's path, as viewed from the equator, is highest in the sky on _________. View Available Hint(s) a. the December solstice b. the June solstice c. the day when Earth is closest to the Sun d. the March and September equinoxes
d
The moon will rise a little _____ each day, and with each passing day you will see a little _____ of the Moon's face illuminated.
later, more
If you wanted to document the apparent retrograde motion of Mars, you would need to measure and record Mars's __________ over a period of ____________
position among the constellations, several months
the larger, surrounding region of an object's shadow in which light from the Sun is only partially blocked
Partial shadow (penumbra)
Stellar parallax occurs in much the same way as parallax on Earth, with greater parallax for stars that are nearer. Return to the main "Parallax" screen, and from here select the "Stellar Parallax" button, and watch how the motion of the star changes in the "View from Earth" window. Which statement best summarizes why stellar parallax occurs? View Available Hint(s) a. We view nearby stars from different positions in Earth's orbit at different times of year. b. We view nearby stars from different positions on Earth as Earth rotates on its axis. c. Nearby stars move in tiny circles as Earth orbits the Sun. d. Nearby stars move at higher speeds relative to the Sun than more distant stars.
a
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 on both the June and December solstices on the June solstice only on the December solstice only on the March equinox only
a
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? View Available Hint(s) a. Your friend will also see a crescent moon. b. Your friend will see a first-quarter moon. c. Your friend will see a gibbous moon. d. Your friend won't see the Moon tonight because it is up only in the morning.
a
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? View Available Hint(s) a. We could not see it at all. b. It would be much brighter because it would be illuminated by the many stars in the center of our galaxy. c. It would look about the same, but it would be harder to pick out because its cloud-like appearance would make it blend in with the cloud-like appearance of the Milky Way in our sky. d. It would look about the same but would be in the constellation Sagittarius instead of Andromeda.
a
We cannot see a new moon in our sky because _________. View Available Hint(s) a. a new moon is quite near the Sun in the sky b. it is obscured by Earth's shadow c. no sunlight is illuminating the Moon d. it is above the horizon during the daytime
a
We describe a location on Earth's surface by stating its _________. View Available Hint(s) a. latitude and longitude b. meridian and longitude c. altitude and direction (or azimuth) d. latitude and direction
a
n angle of 1 arcsecond is _________. View Available Hint(s) a. less than the thickness of a human hair held at arm's length b. about the width of a finger held at arm's length c. about the width of your fist held at arm's length d. slightly more than the width of a basketball held at arm's length
a
As seen from Earth, the Sun appears to follow the annual path that we call the __________ around the celestial sphere. a. ecliptic b. north celestial pole c. celestial equator d. milky way e. south celestial pole f. constellations
a. ecliptic
The Sun-centered system pictured in the lower window of the video offers a simple explanation for observations of apparent retrograde motion. Should these facts alone have been enough to convince the ancient Greeks that Earth really does go around the Sun? View Available Hint(s) a. No, because apparent retrograde motion still happens in an Earth-centered system as the Sun passes by a planet in its orbit around Earth. b. Yes, but the Greeks did not realize it because they never even considered a Sun-centered model. c. Yes, but the Greeks were unable to detect apparent retrograde motion and therefore didn't know that it ruled out an Earth-centered universe. d. No, because the Greeks had an Earth-centered model that also accounted for apparent retrograde motion.
d
Today, astronomers can detect and measure stellar parallax for thousands of the nearest stars, providing us with direct evidence that Earth really does orbit the Sun. Moreover, as the Parallax Angle animation shows (return to the main "Parallax" screen, and select the "Parallax and Distance" button), these measurements allow us to calculate distances to these relatively nearby stars. If we hope to use parallax to measure distances to even more-distant stars, which of the following telescopes would be most useful? View Available Hint(s) a. An extremely large telescope built at the best observing site on Earth b. A larger version of the Hubble Space Telescope, placed in Earth orbit c. A telescope placed on the same orbit of the Sun as Earth, but on the opposite side of the Sun d. A telescope that orbits the Sun in the outer solar system
d
What conditions must exist for a lunar eclipse to occur? View Available Hint(s) a. The only condition is that the phase of the Moon must be new. b. The phase of the Moon must be new and the Moon must be passing through Earth's orbital plane. c. The only condition is that the phase of the Moon must be full. d. The phase of the Moon must be full and the Moon must be passing through Earth's orbital plane.
d
What is really happening in space during the periods when we see Mars going through apparent retrograde motion? View Available Hint(s) a. Earth and Mars are moving in opposite directions around the Sun. b. Mars and the Sun both appear to be in the same constellation as viewed from Earth. c. Mars is moving along its orbit in the opposite direction from the way it usually moves. d. Earth is passing by Mars in its orbit around the Sun.
d
What is stellar parallax? View Available Hint(s) a. It is the change in the set of constellations that we see at different times of year in the evening sky. b. It describes the fact that stars are actually moving relative to one another, even though to our eyes the stars appear fixed in the constellations. c. It is the daily rise and set of the stars. d. It is the slight back-and-forth shifting of star positions that occurs as we view the stars from different positions in Earth's orbit of the Sun.
d
Which of the following statements about the celestial sphere is not true? View Available Hint(s) a. When we look in the sky, the stars all appear to be located on the celestial sphere. b. The Earth is placed at the center of the celestial sphere. c. The celestial sphere does not exist physically. d. The celestial sphere is another name for our universe.
d
Which of the following statements does not use the term angular size or angular distance correctly? View Available Hint(s) a. The angular size of the Sun is about the same as that of the Moon. b. The angular distance between those two houses in the distance is 30 degrees. c. You can use your outstretched hand against the sky to estimate angular sizes and angular distances. d. The angular distance between those two bright stars in the sky is about 2 meters.
d
The Sun rises and sets each day because a. it orbits Earth once each day b. its position seems to change because of stellar parallax c. it undergoes retrograde motion each day d. Earth rotates once each day
d. Earth rotates once each day
Where does the Sun remain above the horizon all day (never setting) on the December solstice? a. Only at the North Pole b. Only at the equator c. Only at the South Pole. d. Everywhere between the Arctic Circle (latitude 66.5°N) and the North Pole e. Everywhere between the Antarctic Circle (latitude 66.5°S) and the South Pole f. Only on the Antarctic Circle (latitude 66.5°S)
e
You discover an asteroid that orbits the Sun with the same 1-year orbital period as Earth. Which of the following statements must be true? a. The asteroid has a more eccentric orbit than Earth. b. The asteroid shares the same orbit around the Sun as Earth. c. The asteroid has the same perihelion distance as Earth. d. The asteroid will eventually collide with Earth. e. The asteroid's average (semimajor axis) distance from the Sun is 1AU.
e