Chapter 2- Astronomy

25 July 2022
4.7 (114 reviews)
127 test answers

Unlock all answers in this set

Unlock answers (123)
question
As seen from Earth, the Sun appears to follow the annual path that we call the __________ around the celestial sphere.
answer
ecliptic
question
The Sun rises and sets each day because
answer
Earth rotates once each day
question
Which of the following statements about phases of the Moon are true? Select all that apply.
answer
-at new moon, we see only the "night" side of the Moon -if it is full moon, the Moon will rise around sunset -the time between new moon and full moon is about two weeks -at new moon, the half of the Moon facing the Sun is fully illuminated
question
A total solar eclipse can only happen during what lunar phase?
answer
New
question
What is the basic reason that we have seasons on Earth?
answer
Earth's axis is tilted relative to the ecliptic plane
question
What happens to Earth's axis as we orbit around the Sun over the course of each year?
answer
It remains pointed in the same direction at all times.
question
Which of the following statements are true about summer compared to winter?
answer
-Temperatures tend to be warmer in summer. -The Sun follows a longer and higher path through your sky in summer. -You have more daylight and less darkness in summer.
question
What is special about the June solstice?
answer
It's the day on which the Northern Hemisphere receives its most direct sunlight.
question
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?
answer
on both the March and September equinoxes
question
A waxing gibbous moon rises at about 3pm, reaches its highest point in the sky at about 9pm, and sets around 3am.
answer
3pm, 9pm, 3am
question
A new moon rises at about sunrise, reaches its highest point in the sky at about noon, and sets around sunset.
answer
Sunrise, noon, sunset
question
A first quarter moon rises at about noon, reaches its highest point in the sky at about sunset, and sets around midnight.
answer
noon, sunset, midnight
question
A waning gibbous moon rises at about 9pm, reaches its highest point in the sky at about 3am, and sets around 9am.
answer
9pm, 3 am, 9am
question
A waxing crescent moon rises at about 9am, reaches its highest point in the sky at about 3pm, and sets around 9pm.
answer
9am, 3pm , 9pm
question
A full moon rises at about sunset, reaches its highest point in the sky at midnight, and sets around sunrise.
answer
sunset, midnight, sunrise
question
Suppose you see a moon that is half bright and half dark in your early evening sky. Then you are seeing a __________ moon.
answer
First Quarter
question
Suppose you see a first quarter moon in your evening sky. How will the Moon's appearance change over the next few days?
answer
The moon will rise a little later each day, and with each passing day you will see a little more of the Moon's face illuminated.
question
Which of the following accurately describe an eclipse season?
answer
-During an eclipse season, there will be a lunar eclipse at full moon. -During an eclipse season, there will be a solar eclipse at new moon. -An eclipse season occurs when the nodes of the Moon's orbit are lined up with Earth and the Sun.
question
Approximately how often do eclipse seasons occur?
answer
Twice a year
question
Eclipse seasons do not occur exactly twice a year. Instead, they occur slightly more often, coming about 173 days apart (which is a bit less than the roughly 182 to 183 days that make up 6 months). Why do they do this, rather than occurring exactly twice each year?
answer
because the line of nodes gradually moves around the Moon's orbit
question
The combination of the 173-day period between eclipse seaons and the Moon's approximately 29 1/2 - day cycle of phases leads to what we call the saros cycle, which lasts about 18 years, 11 1/3 days. Which of the following accurately describe something about the saros cycle?
answer
If there is a solar eclipse in your home town today, there will be a solar eclipse in a different part of the world 18 years, 11 1/3 days from now.
question
Why will total solar eclipses no longer be possible after about 600 million years from now?
answer
The Moon will have moved too far from Earth for it to fully block the Sun.
question
Lunar Eclipse
answer
-occurs when the moon is on the direct opposite side of earth from the sun. -Occurs when earth's shadow falls on the moon -can occur only at full moon -can be seen by anyone on Earth's night side at the time
question
solar eclipse
answer
-Occurs when the moon comes directly between Earth and the Sun -Occurs when the moon's shadow fall on earth -Can be seen only along relatively narrow path on earth -can occur only at new moon
question
the larger, surrounding region of an object's shadow in which light from the Sun is only partially blocked
answer
Partial shadow (penumbra
question
the dark, central region of an object's shadow, in which light from the Sun is fully blocked
answer
Full shadow (umbra
question
What is an annular eclipse?
answer
a solar eclipse in which the Moon does not appear large enough to fully block the Sun
question
When is the next opportunity to see a total solar eclipse in the United States?
answer
April 8, 2024
question
Consider the Moon when it is in the position shown in the moon phase diagram below. How much of the Moon's total surface is illuminated by sunlight at this time?
answer
exactly half
question
Again consider the position of the Moon shown in part A. How much of the Moon's surface is covered by Earth's shadow?
answer
None
question
Again consider the position of the Moon shown in part A. What does the Moon look like in our sky at this time?
answer
Crescent to the right
question
Which of the following best summarizes the reason we see phases of the Moon?
answer
Half the Moon is always illuminated by the Sun, but the phase we see depends on how much of this half we are looking at from Earth
question
Which photo shows what the Moon looks like when it is in the position shown in the following moon phase diagram?
answer
Full Moon
question
Suppose you look up in the sky and the Moon appears as in the photo below. Which of the following diagrams correctly shows the Moon's location in its orbit around Earth for this phase?
answer
Waning gibbous moon diagram
question
Step 1 is to draw a diagram that shows the Moon in the correct position for the phase being considered. Which diagram below correctly shows the location of a third quarter moon?
answer
Third Quarter
question
Step 2 is to place a person in the position on Earth where the Moon would be overhead or at its highest point in the sky and determine the time for that person. At which of the four numbered positions shown below would the person be seeing the third quarter moon be at its highest point in the sky?
answer
4
question
About what time is it for the person who sees the third quarter moon at its highest point (position 4 in the diagram from Part B)?
answer
Sunrise
question
The final step is to determine the rise and set times for this phase. Which of the following are the correct times for a third quarter moon?
answer
rise: about midight; set: about noon
question
Rank the seasons for the Northern Hemisphere based on Earth's distance from the Sun when each season begins, from closest to farthest.
answer
Winter spring fall summer
question
Rank the seasons for the Southern Hemisphere based on Earth's distance from the Sun when each season begins, from closest to farthest.
answer
summer fall spring winter
question
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?
answer
The variation in Earth-Sun distance over the course of each year has virtually no effect on the seasons.
question
You've now seen that Earth's varying distance cannot be the cause of our seasons. So what is the cause of the seasons?
answer
The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
question
True everywhere on Earth
answer
Sun rises due east and sets due west on March equinox
question
Not true anywhere on Earth
answer
Sun reaches zenith (altitude 90 degrees) every day at noon
question
True for Northern Hemisphere
answer
-sun reaches highest point in local sky on June solstice -at high latitudes, Sun never rises on December solstice
question
True for Southern Hemisphere
answer
-Sun traces shortest path across local sky on June solstice -Sun is above horizon for the longest time on December solstice -At high latitudes, Sun never sets on December solstice
question
The Sun reaches the zenith (directly overhead) at midday
answer
-on the equator only on the March and September equinoxes -everywhere within the tropics (between latitudes 23.5°N and 23.5°S) on two dates each year
question
Where does the Sun remain above the horizon all day (never setting) on the December solstice?
answer
Everywhere between the Antarctic Circle (latitude 66.5°S) and the South Pole
question
Although the Causes of Lunar Phases video is very useful for learning about phases of the Moon, it is inaccurate in some ways. Which of the following correctly identify inaccuracies with this video?
answer
-The Moon is too big compared to its orbit. -Earth is too big compared to the Moon's orbit. -The Moon is too big compared to Earth. -The astronaut is too big compared to the Moon.
question
Watch the Causes of Lunar Phases video. To understand phases of the Moon, you must imagine the view from Earth looking out to the Moon as it orbits. At what position(s) in its orbit would we see all of the Moon's daylight side and none of its night side?
answer
at the point on the far left
question
Look again at the Causes of Lunar Phases video. At what position(s) in the Moon's orbit would we see exactly half of the Moon's daylight face and exactly half of its night face?
answer
at the two points at the top and bottom
question
Look again at the Causes of Lunar Phases video. As the Moon orbits, notice how the astronaut's head always points toward Earth. What do we see from Earth that occurs for the same reason? (Be sure you are viewing the first portion of the video, with the rotating Moon, not the hypothetical, non-rotating view, shown afterward.)
answer
We always see the same face of the Moon.
question
Waxing Crescent Moon
answer
visible near western horizon about an hour after sunset sets 2-3 hours after the sun sets
question
Waning Crescent Moon
answer
occurs about 3 days before new moon visible near eastern horizon just before sunrise
question
full moon
answer
rises at about the time the sun sets visible due south at midnight occur 14 days after the new moon
question
A solar eclipse that occurs when the new moon is too far from Earth to completely cover the Sun can be either a partial solar eclipse or a(n)
answer
annular eclipse
question
Anyone looking from the night side of Earth can, in principle, see a(n)
answer
total lunar eclipse
question
During some lunar eclipses, the Moon's appearance changes only slightly, because it passes only through the part of Earth's shadow called the
answer
penumbra
question
A(n) occur only when the Moon is new and has an angular size larger than the Sun in the sky.
answer
total solar eclipse
question
A partial lunar eclipse begins when the Moon first touches Earth's
answer
umbra
question
A point at which the Moon crosses Earth's orbital plane is called a(n
answer
node
question
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.
answer
eastward, westward
question
If you wanted to document the apparent retrograde motion of Mars, you would need to measure and record Mars's position among the constellations over a period of several months.
answer
position among the constellations, several months
question
What is really happening in space during the periods when we see Mars going through apparent retrograde motion?
answer
Earth is passing by Mars in its orbit around the Sun.
question
Consider a time when Mars is in the middle of one of its periods of apparent retrograde motion. During this time, Mars appears brightest in our night sky and crosses the meridian around midnight.
answer
brightest, midnight
question
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?
answer
No, because the Greeks had an Earth-centered model that also accounted for apparent retrograde motion.
question
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?
answer
12
question
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 _____.
answer
2
question
What conditions must exist for a solar eclipse to occur?
answer
it must be new moon the Moon must be passing through Earth's orbital plane
question
What conditions must exist for a lunar eclipse to occur?
answer
it must be full moon the Moon must be passing through Earth's orbital plane
question
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?
answer
Change the Moon's orbital plane so it is in the same plane as Earth's orbit around the Sun.
question
Beginning about 55 seconds into the video, you'll see an animation of a photographer looking through her camera at a man, a set of trees, and distant mountains. Notice that, as viewed through the camera, the positions of the man and the trees change (relative to distant mountains) as the photographer moves. Which of the following statements correctly describes what is really happening in this situation?
answer
The photographer is moving, but the man and the trees are staying still.
question
Consider again the portion of the video discussed in Part A. Notice that in the view through the cameara, the parallax is larger (the apparent movement is larger) for the man than for the trees, and that the mountains do not appear to shift at all. Why?
answer
The amount of parallax depends on an object's distance, with larger parallax for nearer objects.
question
Just as you found for parallax on Earth, stellar parallax is larger for stars that are nearer and smaller for stars that ar more distant. Which statement best summarizes why stellar parallax occurs? You may find it helpful to watch the animation of stellar parallax that begins at about 1:20 into the video.
answer
We view nearby stars from different positions in Earth's orbit at different times of year.
question
Observations of stellar parallax therefore provide direct evidence that:
answer
Earth orbits the Sun some stars are more distant than others
question
As you saw in Part D, 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?
answer
Even for the nearest stars, parallax angles are too small to measure with the naked eye
question
Based on their inability to detect stellar parallax, the ancient Greeks concluded that _________.
answer
either Earth is the center of the universe or stars are extremely far away
question
As discussed in the video, parallax measurements allow us to calculate distances to stars for which parallax is detectable. Suppose you have a telescope capable of measuring parallax shifts of a particular amount (for example, 0.001 arcsecond). Which of the following locations for the telescope would allow you to measure distances to the most distant stars?
answer
a telescope on Mars
question
This diagram represents a simplified model of the celestial sphere. The unlabeled circle that is highlighted in purple represents:
answer
the celestial equator
question
This diagram represents a person's local sky. What does the red semicircle represent?
answer
the meridian
question
What is the approximate latitude and longitude of the South American location marked by the black dot on this diagram?
answer
latitude = 15ºS, longitude = 45ºW
question
Diagrams like this one are commonly used in discussions of seasons and they can be quite useful. However, this diagram greatly exaggerates:
answer
all of the answers listed
question
Which position in this diagram represents Earth on the day that we have the longest amount of daylight in the continental United States?
answer
2
question
Which position in this diagram represents Earth at the beginning of spring for the Southern Hemisphere?
answer
3
question
Which photo shows what we call a first-quarter moon?
answer
2
question
Which photo shows what we call a gibbous moon?
answer
3
question
This multiple exposure photograph shows the apparent retrograde motion of Mars. To make this picture, the photographer needed to combine individual photos of Mars taken over a period of:
answer
several months
question
What is this a picture of?
answer
a total solar eclipse
question
About how many stars are visible to the naked eye on a clear, dark night away from city lights?
answer
a couple thousand
question
What do astronomers mean by a constellation?
answer
A constellation is a region in the sky as seen from Earth
question
What is the ecliptic?
answer
The path the Sun appears to trace around the celestial sphere each year
question
What is the celestial sphere?
answer
The celestial sphere is a representation of how the entire sky looks as seen from Earth.
question
What do we mean when we talk about the Milky Way in our sky?
answer
The patchy band of light that outlines the plane of the Milky Way Galaxy as seen from Earth.
question
Which of the following statements does not use the term angular size or angular distance correctly?
answer
The angular distance between those two bright stars in the sky is about 2 meters.
question
Which of the following correctly describes the meridian in your local sky?
answer
A half-circle extending from your horizon due north, through your zenith, to your horizon due south
question
The point directly over your head is called _________.
answer
the zenith
question
Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called _________.
answer
circumpolar
question
We describe a location on Earth's surface by stating its _________.
answer
latitude and longitude
question
If you are located in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location?
answer
The altitude of the north celestial pole equals your latitude.
question
Which of the following best describes why we have seasons on Earth?
answer
The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.
question
Each choice describes how a few astronomical phenomena are related to time periods. Which list is entirely correct? (Careful: some lists are partially correct.)
answer
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.
question
If we have a new moon today, when we will have the next full moon?
answer
In about two weeks
question
We cannot see a new moon in our sky because _________.
answer
a new moon is quite near the Sun in the sky
question
The Moon always shows nearly the same face to Earth because ________.
answer
the Moon rotates once in the same amount of time that it takes the Moon to orbit Earth once
question
Lunar eclipses can occur only during a _________.
answer
Full moon
question
What is the saros cycle?
answer
The roughly 18-year cycle over which the pattern of eclipses repeats
question
During the time that a planet is in its period of apparent retrograde motion: _________
answer
Over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars
question
What is stellar parallax?
answer
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.
question
Which of the following statements about the celestial sphere is not true?
answer
The celestial sphere is another name for our universe.
question
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?
answer
We could not see it at all.
question
An angle of 1 arcsecond is _________.
answer
less than the thickness of a human hair held at arm's length
question
When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting _________.
answer
higher in the sky
question
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 _________.
answer
latitude 40 degrees south
question
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?
answer
To the right of Polaris; that is, 90 degrees counterclockwise from its current position
question
In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because _________.
answer
our evening view of space depends on where Earth is located in its orbit around the Sun
question
The Sun's path, as viewed from the equator, is highest in the sky on _________.
answer
the March and September equinoxes
question
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?
answer
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.
question
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 _________.
answer
the four seasons would each be twice as long as they are now
question
How does Earth's varying distance from the Sun affect our seasons?
answer
It doesn't; Earth's orbital distance plays no significant role in the seasons.
question
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?
answer
Your friend will also see a crescent moon.
question
Suppose it is full Moon. What phase of Earth would someone on the Moon see at this time?
answer
new earth
question
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?
answer
third quarter
question
You observe a full Moon rising at sunset. What will you see at midnight?
answer
A full moon high in the sky
question
All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new moon?
answer
The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane.
question
For most of history, the lack of observable stellar parallax was interpreted to mean that _________.
answer
Earth is stationary at the center of the universe
question
During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?
answer
Earth is catching up with and passing by Mars in their respective orbits.
question
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 _________.
answer
the Galileo spacecraft that orbited Jupiter in the 1990s