Astronomy 101 Exam 1

Which of the following is a general difference between a planet and a star? -Planets are larger than stars. -Planets are brighter than stars. -Stars glow in infrared and visible light, while planets glow only in the infrared. -All planets are made of rock and all stars are made of gas.

-Stars glow in infrared and visible light, while planets glow only in the infrared.

Look again at the Cause of Lunar Phases animation. At what position(s) in its orbit would we see exactly half of the Moon's daylight face and exactly half of its night face? -at the two points at the top and bottom -at the point on the far right -at the two points on the far left and far right -at the point on the far left

-at the two points at the top and bottom

Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called _________. -circumpolar -celestial -seasonal -bright

-circumpolar

Based on their inability to detect stellar parallax, the ancient Greeks concluded that _________. -the stars must be extremely far away -they lacked the technology necessary for detecting stellar parallax -either Earth is the center of the universe or stars are extremely far away -Earth must be the center of the universe

-either Earth is the center of the universe or stars are extremely far away

Suppose a comet orbits the Sun on a highly eccentric orbit with an average (semimajor axis) distance of 1 AU. How long does it take to complete each orbit, and how do we know? -It depends on the eccentricity of the orbit, as described by Kepler's first law. -Each orbit should take about 2 years, because the eccentricity is so large. -It depends on the eccentricity of the orbit, as described by Kepler's second law. -1 year, which we know from Kepler's third law.

1 year, which we know from Kepler's third law.

Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:

Earth travels faster in its orbit around the Sun in January than in July

Which of the following statements about an ellipse is NOT true? -A circle is considered to be a special type of ellipse. -The semimajor axis of an ellipse is half the length of the longest line that you can draw across an ellipse. -The focus of an ellipse is always located precisely at the center of the ellipse. -An ellipse with a large eccentricity looks much more elongated (stretched out) than an ellipse with a small eccentricity.

The focus of an ellipse is always located precisely at the center of the ellipse.

The Interactive Figure states that the planetary orbits are shown to scale. Which statement correctly describes the way the planet sizes are shown compared to their orbits?***

The planets are all much too large compared to their orbits.

Which of the following orbits has the largest semi major axis?

The semimajor axis is half of the distance across the ellipse in its longest direction (which means half of the major axis), which is also the planet's average distance from the Sun. Therefore, the ellipse that measures the longest across is the one with the largest semi major axis.

-latitude = 15°S, longitude = 45°W

What is the approximate latitude and longitude of the South American location marked by the black dot on this diagram? -latitude = 15°S, longitude = 75°W -latitude = 15°S, longitude = 45°W -latitude = 30°W, longitude = 60°N -latitude = 15°N, longitude = 45°W

-2

Which position in this diagram represents Earth on the day that we have the longest amount of daylight in the continental United States? -4 -3 -1 -2

Earth is farthest from the Sun in July and closest to the Sun in January. During which Northern Hemisphere season is Earth moving fastest in its orbit? -Spring -Summer -Fall -Winter

Winter

You are one year older each time Earth ____________ about the Sun.

orbits

During some lunar eclipses, the Moon's appearance changes only slightly, because it passes only through the part of Earth's shadow called the _____________.

penumbra

According to Kepler's second law, Pluto will be traveling fastest around the Sun when at _________.

perihelion

Our _________ is moving toward the star Vega at about 70,000 km/hr.

solar system

What do we mean when we say that the universe is expanding? -Within galaxies, average distances between star systems are increasing with time. -Average distances between galaxies are increasing with time. -Everything in the universe is gradually growing in size. -The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing.

-Average distances between galaxies are increasing with time.

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? -Make the Moon orbit Earth twice as fast. -Change the Moon's orbital plane so it tilts the opposite way. -Relocate the Moon to twice its current distance from Earth. -Change the Moon's orbital plane so it is in the same plane as Earth's orbit around the Sun.

-Change the Moon's orbital plane so it is in the same plane as Earth's orbit around the Sun.

You observe a full Moon rising at sunset. What will you see at midnight? -A first quarter moon -A third quarter moon -A waning gibbous moon -A full moon high in the sky

-A full moon high in the sky

Note that an observer located at the Local Raisin would see Raisins 1, 2, and 3 all move away from her during the animation. What would an observer located at Raisin 2 see? -Raisin 1 moves toward her while Raisin 3 moves away from her. -Raisin 1 moves away from her while Raisin 3 moves toward her. -Raisin 1 and Raisin 3 both move away from her. -Raisin 1 and Raisin 3 both move toward her.

-Raisin 1 and Raisin 3 both move away from her.

Which of the following statements about the celestial sphere is NOT true? -The Earth is placed at the center of the celestial sphere. -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 does not exist physically.

-The "celestial sphere" is another name for our universe.

Look carefully at this telescopic photo of the Moon. All the following statements are true. Which one is proved by the fact that the line dividing the dark and bright regions is not perfectly straight? -This is a first quarter moon. -Some parts of the Moon's surface are darker in color than others. -The Moon goes around the Earth. -The Moon's surface is not perfectly smooth but rather has mountains and valleys.

-The Moon's surface is not perfectly smooth but rather has mountains and valleys.

The Andromeda Galaxy is faintly visible to the naked eye. When you look at the Andromeda Galaxy, the retina of your eye is absorbing light that has traveled through space for ______ to reach you. -about 2 ½ million years -about 100,000 years -a few minutes -about 250 years

-about 2 ½ million years

On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun? -about the distance across the United States -100 meters -about the distance across the state of Delaware -about the distance across 50 football fields

-about the distance across the United States

Suppose that someone in the Andromeda galaxy had a super-telescope through which they were looking at Earth right now. They would see Earth ______. -as it was about 100,000 years ago -as it will be about 2 ½ million years from now -as it is right now -as it was about 2 ½ million years ago

-as it will be about 2 ½ million years from now

If we have a new moon today, when we will have the next full moon? -in about 1 week -in about 2 weeks -in about 6 months -in about a month

-in about 2 weeks

In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because _________. -some constellations are circumpolar -during some times of year, some constellations drop below the southern horizon -on any particular night, we can only see stars that are directly opposite (180 degrees away from) the Sun in the sky -our evening view of space depends on where Earth is located in its orbit around the Sun

-our evening view of space depends on where Earth is located in its orbit around the Sun

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 _________. -stars would take twice as long to rise and set -the cycle of precession would take 13,000 years instead of 26,000 years -the four seasons would each be twice as long as they are now -the Earth would not have seasons

-the four seasons would each be twice as long as they are now

It's 6 am and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase? -full -new -first quarter -third quarter

-third quarter

When it is summer in Australia, the season in the United States is -winter -summer -spring

-winter

-a total solar eclipse

What is this a picture of? -a full moon -a total lunar eclipse -the saros cycle -a total solar eclipse

-2

Which photo shows what we call a first quarter moon? -2 -1 -3 -4

-3

Which photo shows what we call a gibbous moon? -1 -3 -4 -2

How does a 12-month lunar calendar differ from our 12-month solar calendar? -It has about 11 fewer days. -It uses a 23-hour rather than a 24-hour day. -Its new year always occurs in February instead of on January 1. -It does not have seasons.

It has about 11 fewer days.

Which of the following planets has essentially no seasons at all? -Neptune (axis tilt = 29.6°) -Jupiter (axis tilt = 3.1°) -Mars (axis tilt = 25.2°) -Uranus (axis tilt = 97.9°)

Jupiter (axis tilt = 3.1°) With almost no axis tilt at all, Jupiter does not have seasons.

According to Kepler's third law:

Jupiter orbits the Sun at a faster speed than Saturn.

A point at which the Moon crosses Earth's orbital plane is called a(n) ___________.

node

Look again at the Cause of Lunar Phases animation. To understand phases of the Moon, you must imagine the view from Earth (in the center of the animation) 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? -at the point on the far left -at the point on the far right -at the two points on the far left and far right -at the two points at the top and bottom

-at the point on the far left

What do we mean by a geocentric model of the universe? -a model of the Milky Way Galaxy that has our solar system located at its center -a model designed to explain what we see in the sky while having Earth orbit the Sun -a model designed to explain what we see in the sky while having Earth located in the center of the universe -the name given to sphere-shaped models that show all the constellations as they appear in our sky on the celestial sphere

A model designed to explain what we see in the sky while having Earth located in the center of the universe

According to Kepler's third law (p2 = a3), how does a planet's mass affect its orbit around the Sun? -More massive planets orbit the Sun at higher average speed. -A more massive planet must have a larger semimajor axis. -A planet's mass has no effect on its orbit around the Sun. -More massive planets must have more circular orbits.

A planet's mass has no effect on its orbit around the Sun.

Suppose it is full Moon. What phase of Earth would someone on the Moon see at this time? -first quarter Earth -Earth does not go through phases as seen from the Moon. -full Earth -new Earth

-new Earth

This figure shows the circle upon circle motion of a planet in the Ptolemaic model. At which point(s) is the planet in the middle of its period of retrograde motion in our sky?

2 only. The planet moves around the smaller circle while the small circle moves around the larger circle, with the result path indicated by the dashed curve. Notice that the planet moves backward (apparent retrograde motion) whenever it is moving on the side of the small circle closer to Earth; Point 2 is in the middle of this part of the small circle and hence represents the middle of the period of apparent retrograde motion.

Scientific thinking is _________. -a difficult process that only a handful of people can do well -based on everyday ideas of observation and trial-and-error experiments -an ancient mode of thinking first invented in Egypt -completely different from any other type of thinking

based on everyday ideas of observation and trial-and-error experiments

The great contribution of Nicholas Copernicus was to _________. -discover the laws of planetary motion -create a detailed model of our solar system with the Sun rather than Earth at the center -discover the law of gravity -prove that Earth is not the center of the universe

create a detailed model of our solar system with the Sun rather than Earth at the center

Galileo's contribution to astronomy included:

Making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.

Imagine that Venus is in its full phase today. If we could see it, at what time would the full Venus be highest in the sky?

Noon (Because Venus is full when it is on the opposite side of the Sun from Earth, the Sun and Venus both appear to move through the sky together at that time. Venus therefore rises with the Sun, reaches its highest point at noon, and sets with the Sun.)

When would a new Venus be highest in the sky?

Noon (You probably noticed that a new Venus occurs when Venus is directly between the Sun and Earth, which means a new Venus will be high in the sky at the same time that the Sun is high in the sky.)

According to Kepler's second law, Jupiter will be traveling most slowly around the Sun when at ________.

aphelion

The extent to which Mars' orbit differs from a perfect circle is called its ________.

eccentricity

We cannot see a new moon in our sky because _________. -a new moon is quite near the Sun in the sky -it is above the horizon during the daytime -it is obscured by Earth's shadow -no sunlight is illuminating the Moon

-a new moon is quite near the Sun in the sky

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? -Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. -Venus orbits the Sun faster than Earth orbits the Sun. -The Sun is located slightly off-center from the middle of each planet's orbit. -All the planets orbit the Sun in nearly the same plane. -Inner planets orbit the Sun at higher speed than outer planets. -Earth is slightly closer to the Sun on one side of its orbit than on the other side.

- Earth is slightly closer to the Sun on one side of its orbit than on the other side - The Sun is located slightly off-center from the middle of each planet's orbit

For most of history, the lack of observable stellar parallax was interpreted to mean that _________. -stars were too far away for parallax to be measured with available technology -Earth is stationary at the center of the universe -stars must all lie at the same distance from Earth, on the celestial sphere -Galileo's theories of the universe were essentially correct

-Earth is stationary at the center of the universe

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 _____. Check two responses below, one for each of the two blanks in the question. -(Blank 1) dimmest -(Blank 1) brightest -(Blank 2) noon -(Blank 2) dusk -(Blank 2) midnight -(Blank 2) dawn

-(Blank 1) brightest -(Blank 2) midnight

If you wanted to document the apparent retrograde motion of Mars, you would need to measure and record Mars's __________ over a period of __________. Check two responses below: one for each of the two blanks in the question. -(Blank 1) position among the constellations -(Blank 1) angular distance from the Sun in the sky -(Blank 1) altitude and direction in the sky -(Blank 1) speed as it moves east to west across the sky -(Blank 2) about 4 to 6 hours -(Blank 2) one full night -(Blank 2) about one week -(Blank 2) several months

-(Blank 1) position among the constellations -(Blank 2) several months

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. Check two responses below, one for each of the two blanks in the question. -(Blank 1) to the right (westward) -(Blank 1) to the left (eastward) -(Blank 1) fast -(Blank 1) slow -(Blank 2) to the right (westward) -(Blank 2) to the left (eastward) -(Blank 2) fast -(Blank 2) slo

-(Blank 1) to the left (eastward) -(Blank 2) to the right (westward)

If the 14 billion year history of the universe were compressed to one year, and "now" is exactly midnight December 31, approximately how long ago were your grandparents born? -1 hour ago -1 minute ago -1 second ago -0.15 second ago

-0.15 second ago

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? -Jupiter's orbital period is 5.2032 times Earth's orbital period. -11.862=5.2033 -5.2032=11.863 -Jupiter's orbital period is 5.2033 times Earth's orbital period.

-11.862=5.2033

Suppose the planet Uranus were much brighter in the sky, so that it was as easily visible to the naked eye as Jupiter or Saturn. Which one of the following statements would most likely be true in that case? -A week would have eight days instead of seven. -Its brightness would make it possible to read by starlight at night. -Its gravity would cause the tides to be much higher than they actually are. -Its slow motion through the sky would have led it to be named after the Goddess of Procrastination. -The discovery that the Earth is a planet going around the Sun would have come hundreds of years earlier.

A week would have eight days instead of seven.

Refer to the data in the introduction. Rank the seasons for the Northern Hemisphere based on Earth's distance from the Sun when each season begins, from closest to farthest.

Closest to the Sun: Winter Spring Fall Summer :Farthest from the Sun Many people guess that seasons are caused by variations in Earth's distance from the Sun, but if that were the case, we'd expect it to be warmest (summer) when Earth is closest to the Sun. As you can see in the rankings, Earth is actually farthest from the Sun when it is summer in the Northern Hemisphere. We conclude that variations in the Earth-Sun distance from are not the major cause of our seasons.

Tycho Brahe's contribution to astronomy included:

Collecting data that enabled Kepler to discover the laws of planetary motion

Which of these four ellipses has the greatest eccentricity?

Eccentricity describes the amount by which an ellipse is stretched out compared to a perfect circle. Because Ellipse 4 is the most stretched out of the four ellipses shown, it has the greatest eccentricity.

Which of the following orbits is the most eccentric?

Eccentricity is a measure of how "stretched out" an ellipse is. A perfect circle has zero eccentricity, and the most stretched out ellipse has the largest eccentricity.

Only one of the statements below uses the term theory in its correct, scientific sense. Which one? -I wrote a theory that is 152 pages long. -I have a new theory about the cause of earthquakes, and I plan to start testing it soon. -Evolution is only a theory, so there's no reason to think it really happened. -Einstein's theory of relativity has been tested and verified thousands of times.

Einstein's theory of relativity has been tested and verified thousands of times.

In Ptolemy's Earth-centered model for the solar system, Venus's phase is never full as viewed from Earth because it always lies between Earth and the Sun. In reality, as Galileo first recognized, Venus is __________.

Full whenever it is on the opposite side of the Sun from Earth, although we cannot see the full Venus because it is close to the Sun in the sky.

Which of the following is not true about scientific progress?

Science advances only through the scientific method.

Which of the following is not true about scientific progress? -Science progresses through the creation and testing of models of nature. -Science advances only through the scientific method. -Science avoids explanations that invoke the supernatural.

Science advances only through the scientific method.

Shown following are five different phases of the Moon as seen by an observer in the Northern Hemisphere. Imagine that tonight the Moon is in the waxing gibbous phase (as shown at the far left (labeled "first") in the following ranking box). Rank the pictured phases from left to right based on the order in which you would see them over the next four weeks, from first seen to last.

((( (( ( ) )) ))) Remember that "waxing" phases mean on the way to full moon and "waning" phases mean after full moon. So if tonight is a waxing gibbous moon, then we are headed toward full moon in about three to four days. Because the full moon is not shown, we'd next see a waning gibbous moon, then a third-quarter moon, and then a waning crescent. From there we'd have new moon (which isn't shown), then the waxing crescent, and then first-quarter. Finally, a full four weeks from now (actually 29 1/2 days), we'd once again have a waxing gibbous moon.

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? -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 -2 -12 -24

-2

What do astronomers mean by a constellation? -A constellation is a region in the sky as seen from Earth. -A constellation is any random grouping of stars in the sky. -A constellation is a group of stars related through an ancient story. -A constellation is a group of stars that are all located in about the same place in space.

-A constellation is a region in the sky as seen from Earth.

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, 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? -A telescope placed on the same orbit of the Sun as Earth, but on the opposite side of the Sun -A telescope that orbits the Sun in the outer solar system -A larger version of the Hubble Space Telescope, placed in Earth orbit -An extremely large telescope built at the best observing site on Earth

-A telescope that orbits the Sun in the outer solar system

During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space? -Mars is moving around the Sun in the opposite direction from which Earth is moving around the Sun. -Earth is catching up with and passing by Mars in their respective orbits. -Earth and Mars are getting closer together. -Earth and Mars are on opposite sides of the Sun.

-Earth is catching up with and passing by Mars in their respective orbits.

When we see Saturn going through a period of apparent retrograde motion, it means: -Saturn is temporarily moving backward in its orbit of the Sun. -Earth is passing Saturn in its orbit, with both planets on the same side of the Sun. -Saturn and Earth must be on opposite sides of the Sun.

-Earth is passing Saturn in its orbit, with both planets on the same side of the Sun.

What is really happening in space during the periods when we see Mars going through apparent retrograde motion? -Earth is passing by Mars in its orbit around the Sun. -Earth and Mars are moving in opposite directions around the Sun. -Mars and the Sun both appear to be in the same constellation as viewed from Earth. -Mars is moving along its orbit in the opposite direction from the way it usually moves.

-Earth is passing by Mars in its orbit around the Sun.

Although this Cause of Lunar Phases animation 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 animation? Check all that apply. -The Moon is too small compared to Earth. -Earth is rotating much too fast relative to the speed of the Moon's orbit in the animation. -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. -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. -The Moon is too big compared to its orbit.

Which of the following lies in the ecliptic plane? -Earth's equator -Earth's orbital path around the Sun -A line connecting Earth's north and south poles -A line connecting Earth and Polaris

-Earth's orbital path around the Sun

Which of the following correctly lists our "cosmic address" from small to large? -Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe; -Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe; -Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe

-Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe;

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? -Their belief in an Earth-centered universe meant that they did not expect parallax, and therefore did not look for it. -Even for the nearest stars, parallax angles are too small to measure with the naked eye. -The Greeks thought all the stars were the same distance away, residing on a celestial sphere. -Some Greeks actually did measure it, but they did not understand the importance of their measurements.

-Even for the nearest stars, parallax angles are too small to measure with the naked eye.

When we say that a planet has a highly eccentric orbit, we mean that: -It is spiraling in toward the Sun. -Its orbit is an ellipse with the Sun at one focus. -In some parts of its orbit it is much closer to the Sun than in other parts.

-In some parts of its orbit it is much closer to the Sun than in other parts.

How does Earth's varying distance from the Sun affect our seasons? -It makes summer warmer in the Northern Hemisphere than in the Southern Hemisphere. -It causes the seasons to be more extreme than they would be if the Earth's distance from the Sun were always the same. -It doesn't --- Earth's orbital distance plays no significant role in the seasons. -It is responsible for the fact that the seasons are opposite in the Northern and Southern hemispheres.

-It doesn't --- Earth's orbital distance plays no significant role in the seasons.

Which of the following was not a major advantage of Copernicus's Sun-centered model over the Ptolemaic model? -It made significantly better predictions of planetary positions in our sky. -It offered a more natural explanation for the apparent retrograde motion of planets in our sky. -It allowed calculation of the orbital periods and distances of the planets.

-It made significantly better predictions of planetary positions in our sky.

The table in the animation shows you the speeds of Raisins 1, 2, and 3 as measured from the Local Raisin. Suppose instead you measured speeds as seen from Raisin 2. An observer at Raisin 2 would measure __________. -Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr -Local Raisin speed = 2.0 cm/hr; Raisin 1 speed = 4.0 cm/hr; Raisin 3 speed = 6.0 cm/hr -Local Raisin speed = 6.0 cm/hr; Raisin 1 speed = 4.0 cm/hr; Raisin 3 speed = 2.0 cm/hr -Local Raisin speed = 2.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr -Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 4.0 cm/hr

-Local Raisin speed = 4.0 cm/hr; Raisin 1 speed = 2.0 cm/hr; Raisin 3 speed = 2.0 cm/hr

Based on what you have learned from your rankings in Parts A and B, which of the following planets would you expect to have seasons most like Earth's? -Uranus (axis tilt = 97.9°) -Jupiter (axis tilt = 3.1°) -Mars (axis tilt = 25.2°)

-Mars (axis tilt = 25.2°) The seasonal temperature changes on Mars are quite similar in their pattern to those on Earth because Mars's axis tilt is so similar to Earth's. (Note, however, that while Earth's varying distance from the Sun plays essentially no role in our seasons, the same is not true on Mars. Because Mars has a more elliptical orbit and hence a much greater distance variation than Earth, distance from the Sun plays an important secondary role in the seasons on Mars.)

All of the following statements are true. Which one can be explained by Kepler's second law? -All the planets orbit the Sun in nearly the same plane. -Earth is slightly closer to the Sun in January than in July. -The Sun is not in the precise center of Saturn's orbit. -Venus orbits the Sun at a faster orbital speed than Earth. -Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun.

-Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun.

The Sun-centered system pictured in the lower window of the animation 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? -Yes, but the Greeks did not realize it because they never even considered a Sun-centered model. -No, because apparent retrograde motion still happens in an Earth-centered system as the Sun passes by a planet in its orbit around Earth. -Yes, but the Greeks were unable to detect apparent retrograde motion and therefore didn't know that it ruled out an Earth-centered universe. -No, because the Greeks had an Earth-centered model that also accounted for apparent retrograde motion.

-No, because the Greeks had an Earth-centered model that also accounted for apparent retrograde motion

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? -Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. -Venus orbits the Sun faster than Earth orbits the Sun. -The Sun is located slightly off-center from the middle of each planet's orbit. -All the planets orbit the Sun in nearly the same plane. -Inner planets orbit the Sun at higher speed than outer planets. -Earth is slightly closer to the Sun on one side of its orbit than on the other side.

-Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.

As you play the Moon Orbit animation, notice how the arrows representing the Sun's rays are at first spread apart, but become parallel as the animation zooms in to the Moon's orbit. Why do the Sun's rays become parallel at the end of the animation? -The rays that reach Earth and the Moon come from only one very small spot on the Sun. -Rays from the Sun that start out going in different directions turn toward Earth as they travel away from the Sun. -The animation is incorrect; the Sun's rays actually converge on the Moon from all directions, not just as parallel rays. -The Sun is so far away compared to the size of the Moon's orbit that all the rays reaching the orbit come from essentially the same direction.

-The Sun is so far away compared to the size of the Moon's orbit that all the rays reaching the orbit come from essentially the same direction.

In the Introduction to Parallax animation, notice that the parallax is greater (the apparent movement is larger) for the person than for the trees, and that the mountains do not appear to shift at all. Why? -The amount of parallax depends on an object's distance, with greater parallax for nearer objects. -The amount of parallax depends on an object's distance, with greater parallax for more distant objects. -The amount of parallax depends on an object's size, with greater parallax for larger objects. -The amount of parallax depends on an object's size, with greater parallax for smaller objects.

-The amount of parallax depends on an object's distance, with greater parallax for nearer objects.

Which of the following statements does NOT use the term angular size or angular distance correctly? -The angular distance between those two bright stars in the sky is about 2 meters. -The angular distance between those two houses in the distance is 30 degrees. -The angular size of the Sun is about the same as that of the Moon. -You can use your outstretched hand against the sky to estimate angular sizes and angular distances.

-The angular distance between those two bright stars in the sky is about 2 meters.

When we say the universe is expanding, we mean that: -Everything in the universe is growing in size. -The average distance between galaxies is growing with time. -The universe is getting older.

-The average distance between galaxies is growing with time.

Which of the following statements best describes what astronomers mean when they say that the universe is expanding? -The average distance between galaxies is increasing with time. -The observable universe is growing larger in radius at a rate of one light-year per year. -The universe itself is not growing, but our knowledge of the universe is increasing with time. -All objects in the universe, including Earth and everything on it, are gradually growing in size. -The average distance between stars in the Milky Way Galaxy is increasing with time.

-The average distance between galaxies is increasing with time.

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? -Polaris would not be our North star. -The region of Earth where the Sun does not rise on the winter solstice would be larger (extending farther south) than it is 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. -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.

All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new moon? -The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane. -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 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.

How would a star's parallax change as its distance from Earth increases? -The parallax shift increases as the star's distance from Earth increases. -The parallax shift does not change; it is independent of the star's distance from Earth. -The parallax shift decreases as the star's distance from Earth increases.

-The parallax shift decreases as the star's distance from Earth increases.

What conditions must exist for a lunar eclipse to occur? -The only condition is that the phase of the Moon must be new. -The phase of the Moon must be new and the Moon must be passing through Earth's orbital plane. -The only condition is that the phase of the Moon must be full. -The phase of the Moon must be full and the Moon must be passing through Earth's orbital plane.

-The phase of the Moon must be full and the Moon must be passing through Earth's orbital plane.

What conditions must exist for a solar eclipse to occur? -The only condition is that the phase of the Moon must be new. -The phase of the Moon must be new and the Moon must be passing through Earth's orbital plane. -The only condition is that the phase of the Moon must be full. -The phase of the Moon must be full and the Moon must be passing through Earth's orbital plane.

-The phase of the Moon must be new and the Moon must be passing through Earth's orbital plane.

The Introduction to Parallax animation demonstrates the basic idea of parallax. Click the play button, and watch how the motion of the photographer (lower window) affects what the camera sees (upper window). Which of the following statements correctly describes what is really happening? (Note: You need not continue with the next button to answer this question.) -The photographer, the person being photographed, and the trees are all moving at the same speed. -The photographer is moving, but the person being photographed and the trees are staying still. -The photographer is staying still, but the person being photographed and the trees are moving. -The trees are moving more slowly than the person being photographed, who is moving more slowly than the photographer.

-The photographer is moving, but the person being photographed and the trees are staying still.

The following statements describe ways in which the analogy might apply to the real universe. Which statements are correct? -Both the raisin cake and the universe have a well-defined inside and outside. -Raisin 1 is near the center of the cake, just as our galaxy is near the center of the universe. -The raisins stay roughly the same size as the cake expands, just as galaxies stay roughly the same size as the universe expands. -An observer at any raisin sees more distant raisins moving away faster, just as an observer in any galaxy sees more distant galaxies moving away faster. -The temperature starts low and ends high in both the raisin cake and the universe. -The average distance increases with time both between raisins in the cake and between galaxies in the universe.

-The raisins stay roughly the same size as the cake expands, just as galaxies stay roughly the same size as the universe expands. -An observer at any raisin sees more distant raisins moving away faster, just as an observer in any galaxy sees more distant galaxies moving away faster. -The average distance increases with time both between raisins in the cake and between galaxies in the universe.

Which of the following best describes why we have seasons on Earth? -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. -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. -The tilt of Earth's axis causes different portions of Earth to receive more or less direct sunlight at different times of year. -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.

-The tilt of Earth's axis causes different portions of Earth to receive more or less direct sunlight at different times of year.

What do astronomers mean by the Big Bang? -the explosion of a massive star at the end of its life -the event that marked the birth of our solar system -a gigantic explosion that blew all the galaxies in the universe to smithereens -the event that marked the beginning of the expansion of the universe

-the event that marked the beginning of the expansion of the universe

The fact that nearly all galaxies are moving away from us, with more distant ones moving faster, helped us to conclude that: -The universe is expanding. -Galaxies repel each other like magnets. -Our galaxy lies near the center of the universe.

-The universe is expanding.

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 left of Polaris; that is, 90 degrees clockwise from its current position -Still in the same place, below Polaris -Directly above Polaris -To the right of Polaris; that is, 90 degrees counterclockwise from its current position

-To the right of Polaris; that is, 90 degrees counterclockwise from its current position

In January, Earth's rotation axis points in the direction of the star Polaris. Where does it point in July? -Toward the star Sirius -Toward a star 23 ½° away from Polaris -Toward the star Polaris -Toward a star 47° away from Polaris

-Toward the star Polaris

Which of the following planets should have the most extreme seasons? -Neptune (axis tilt = 29.6°) -Uranus (axis tilt = 97.9°) -Jupiter (axis tilt = 3.1°) -Mars (axis tilt = 25.2°)

-Uranus (axis tilt = 97.9°) Uranus is tipped nearly on its side; its axis tilt of 97.9° is equivalent to 180° - 97.9° = 82.1°, but with the "north" pole tipped to below the ecliptic plane. This tilt of close to 90° gives Uranus very extreme seasons.

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? -Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. -Venus orbits the Sun faster than Earth orbits the Sun. -The Sun is located slightly off-center from the middle of each planet's orbit. -All the planets orbit the Sun in nearly the same plane. -Inner planets orbit the Sun at higher speed than outer planets. -Earth is slightly closer to the Sun on one side of its orbit than on the other side.

-Venus orbits the Sun faster than Earth orbits the Sun - Inner planets orbit the Sun at higher speed than outer planets

Look again at the Cause of Lunar Phases animation. 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 animation with the rotating Moon, not the hypothetical, non-rotating view.) -We see different faces of the Moon at different times. -We see phases of the Moon. -Astronauts on the Moon sometimes appear to hang upside-down. -We always see the same face of the Moon.

-We always see the same face of the Moon

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. -It would be much brighter, because it would be illuminated by the many stars in the center of our galaxy. -It would look about the same, but would be in the constellation Sagittarius instead of Andromeda. -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.

-We could not see it at all.

Based on what you have learned from your rankings in Parts A and B, why is it generally hotter in summer than in winter? Check all that apply. -We are closer to the Sun in the summer. -Earth rotates more rapidly in summer. -We have more hours of daylight in summer. -The Sun is higher in the sky in summer.

-We have more hours of daylight in summer. -The Sun is higher in the sky in summer. Two factors make it warmer in the summer: (1) the Sun is higher in the sky, which means more direct sunlight; (2) we have more total hours in sunlight each day. Notice that both factors are a result of Earth's axis tilt relative to the Sun, which is why we say that axis tilt is the cause of the seasons.

Today, the evidence that we live in an expanding universe is extremely strong, because astronomers have measured the motions of millions of galaxies. Nevertheless, in science, we must always remain open to the possibility that some future observation could call even our most strongly supported theories into question. Which of the following hypothetical observations would not be consistent with what we expect in an expanding universe? -You discover a pair of distant galaxies that are colliding with one another. -You discover an extremely distant galaxy that is moving toward us. -You discover an extremely distant galaxy that is moving away from us at 90% of the speed of light.

-You discover an extremely distant galaxy that is moving toward us.

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 won't see the Moon tonight, because it is up only in the morning. -Your friend will see a gibbous moon. -Your friend will see a first quarter moon. -Your friend will also see a crescent moon

-Your friend will also see a crescent moon

According to current scientific estimates, when did the Big Bang occur? -about 20 billion years ago -about 14 billion years ago -about 10 billion years ago -about 4 1/2 billion years ago -about 65 million years ago

-about 14 billion years ago

Play the Moon Orbit animation through to the end, where you see the Moon orbiting Earth at correctly scaled sizes. Notice that Earth's daylight side (white) is on the right in this view, and its night side (gray) is on the left. Where along its orbit would the Moon also have its daylight side on the right and its night side on the left? -only at the point on the far right (the new moon position) -only at the point on the far left (the full moon position) -only at the two points on the far left and far right (the new and full moon positions) -only at the two points at the top and bottom (the first- and third-quarter positions) -everywhere along its orbit

-everywhere along its orbit

Lunar eclipses can occur only during a _________. -third quarter moon -full moon -first quarter moon -new moon

-full moon

When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting _________. -lower in the sky -higher in the sky -dimmer -brighter

-higher in the sky

On the cosmic calendar, which compresses the history of the universe into a single year, about when did life arise on Earth? -in late January -in mid-August -in September -in mid-December -just a few hours before midnight on December 31

-in September

On the cosmic calendar, which compresses the history of the universe into a single year, about when did Earth form? -very early in January -in mid-February -in June -in early September -in mid-December

-in early September

We never see a crescent Jupiter from Earth because Jupiter __________. -shines with its own light -is farther than Earth from the Sun -does not go around Earth -orbits the Sun in the same direction as Earth

-is farther than Earth from the Sun

Start at the beginning of the Moon Orbit animation, which shows the Sun and part of Earth's orbit. If we wanted to show the Moon's orbit on the scale of this starting frame, we would need to draw a circle that __________. -has a diameter that is about half the distance between Earth's orbit and Venus's orbit -is about twice the size of the white dot representing the Sun -has a diameter that is about 1/4 of the distance between Earth's orbit and Venus's orbit -is smaller than one of the green dashes that show Earth's orbit

-is smaller than one of the green dashes that show Earth's orbit

A television advertisement claiming that a product is light-years ahead of its time does not make sense because _________. -light-years can only be used to talk about light -a light-year is an astronomically large unit, so a product could not possibly be so advanced -it doesn't specify the number of light-years -it uses "light-years" to talk about time, but a light-year is a unit of distance

-it uses "light-years" to talk about time, but a light-year is a unit of distance

On the cosmic calendar, which compresses the history of the universe into a single year, about when did early humans first walk on Earth? -in June -in September -in mid-December -on December 30 -just a few hours before midnight on December 31

-just a few hours before midnight on December 31

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 north -latitude 50 degrees south -longitude 40 degrees -latitude 40 degrees south

-latitude 40 degrees south

An angle of 1 arcsecond is _________. -about the width of your fist held at arm's length -about the width of a finger held at arm's length -slightly more than the width of a basketball held at arm's length -less than the thickness of a human hair held at arm's length

-less than the thickness of a human hair held at arm's length

The age of our solar system is about: -one-third of the age of the universe. -three-fourths of the age of the universe. -two billion years less than the age of the universe.

-one-third of the age of the universe.

During the time that a planet is in its period of apparent retrograde motion, _________. -over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars -the planet moves backwards (clockwise as viewed from above Earth's north pole) in its orbit of the Sun -the planet is getting closer to the Sun in its orbit -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

-over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars

What is the "Raisin Cake model" intended to explain? -that every raisin in a raisin cake moves farther away from every other raisin: there is no special central raisin (and no special central galaxy) -that the universe heats up as it expands, just like the raisin cake heats and expands -that raisins, like galaxies, expand with the rest of the universe -that all the raisins in the cake move away from one central raisin, just as all galaxies are moving away from one special galaxy (ours)

-that every raisin in a raisin cake moves farther away from every other raisin: there is no special central raisin (and no special central galaxy)

The term observable universe refers to _________. -that portion of the universe that we have so far photographed through telescopes -the portion of the universe that is not hidden from view by, for example, being below the horizon -that portion of the universe that we can see in principle, given the current age of the universe -the portion of the universe that can be seen by the naked eye

-that portion of the universe that we can see in principle, given the current age of the universe

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 _________. -the Galileo spacecraft that orbited Jupiter in the 1990s -the Arecibo radio telescope in Puerto Rico -the Hubble Space Telescope (which orbits Earth) -the Keck telescope on Mauna Kea, Hawaii

-the Galileo spacecraft that orbited Jupiter in the 1990s

Our solar system consists of _________. -a few hundred billion stars, bound together by gravity -the Sun and all the objects that orbit it -the Sun and the planets, and nothing else -the Sun and several nearby stars, as well as the planets and other objects that orbit these stars

-the Sun and all the objects that orbit it

What is the ecliptic? -the path traced by the Moon's shadow on Earth during a solar eclipse -the Sun's daily path from east to west in our sky -a half-circle extending from your horizon due north, through your zenith, to your horizon due south -the path the Sun appears to trace around the celestial sphere each year

-the path the Sun appears to trace around the celestial sphere each year

Consider the hypothetical observation "a planet beyond Saturn rises in west, sets in east." This observation is not consistent with a Sun-centered model, because in this model __________. -planets beyond Saturn must orbit the Sun more slowly than closer-in planets -the rise and set of all objects depends only on Earth's rotation -there are no planets beyond Saturn -all objects in space must orbit the Sun in the same direction

-the rise and set of all objects depends only on Earth's rotation

The Sun's path, as viewed from the equator, is highest in the sky on _________. -the winter solstice -the summer solstice -the spring and fall equinoxes -the day when Earth is closest to the Sun

-the spring and fall equinoxes

Which of the following best describes what we mean by the universe? -a vast collection of stars that number as many as the grains of sand on all the beaches on Earth -all the galaxies in all the superclusters -the sum total of all matter and energy -our Milky Way Galaxy

-the sum total of all matter and energy

Based on what you've learned from the raisin cake analogy, what two properties of distant galaxies do astronomers have to measure to show that we live in an expanding universe? -their distances and masses -their ages and masses -their distances and speeds -their ages and distances

-their distances and speeds

Which of the following is not part of a good scientific theory? -A scientific theory must make testable predictions that, if found to be incorrect, could lead to its own modification or demise. -A scientific theory should be based on natural processes and should not invoke the supernatural or divine. -A scientific theory cannot be accepted until it has been proven true beyond all doubt. -A scientific theory must explain a wide variety of phenomena observed in the natural world.

A scientific theory cannot be accepted until it has been proven true beyond all doubt.

Which of the following is not true about a scientific theory? -A theory is essentially an educated guess. -A theory must explain a wide range of observations or experiments. -Even the strongest theories can never be proved true beyond all doubt.

A theory is essentially an educated guess.

Look once more at the objects you ranked in Parts A and B. This time, rank the objects from left to right based on how much they have aged since they emitted the light we see today, from greatest to least.

Aged Most: 1.Star on the far side of the Andromeda Galaxy 2.Star on the near side of the Andromeda Galaxy 3.Star on far side of Milky Way Galaxy 4.Star near center of Milky Way Galaxy 5. Orion Nebula 6.Alpha Centauri 7.Pluto 8.The Sun :Aged Least

Each of the four diagrams below represents the orbit of the same comet, but each one shows the comet passing through a different segment of its orbit around the Sun. During each segment, a line drawn from the Sun to the comet sweeps out a triangular-shaped, shaded area. Assume that all the shaded regions have exactly the same area. Rank the segments of the comet's orbit from left to right based on the length of time it takes the comet to move from Point 1 to Point 2, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Although Kepler wrote his laws specifically to describe the orbits of the planets around the Sun, they apply more generally. Kepler's second law tells us that as an object moves around its orbit, it sweeps out equal areas in equal times. Because all the areas shown here are equal, the time it takes the comet to travel each segment must also be the same.

Which of the following orbits shows the planet at aphelion?

Aphelion is the point in a planet's orbit that is farthest from the Sun.

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. -The area swept out in January is larger. -Both areas are the same.

Both areas are the same.

Refer to the data in the introduction. Rank the seasons for the Southern Hemisphere based on Earth's distance from the Sun when each season begins, from closest to farthest.

Closest to the Sun: Summer Fall Spring Winter :Farthest from the Sun The fact that the two hemispheres have opposite seasons is further proof that the seasons are not caused by Earth's varying distance from the Sun. Keep in mind that Earth is so small in size (diameter 12,800 km) compared to its distance from the Sun (about 150 million km) that there is no significant difference in the distances of the two hemispheres from the Sun; therefore, if the seasons were caused by Earth's varying distance from the Sun, the entire Earth would have summer at the same time.

The astrology practiced by those who cast predictive horoscopes can be tested by __________ -asking astrologers if it works. -counting how many times the predictions come true. -comparing how often the predictions come true to what would be expected by pure chance. -polling people to find out what percentage believe their horoscopes to be accurate.

Comparing how often the predictions come true to what would be expected by pure chance.

When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not? -Copernicus misjudged the distances between the planets. -Copernicus placed the planets in the wrong order going outward from the Sun. -Copernicus placed the Sun at the center, but did not realize that the Moon orbits the Earth. -Copernicus used perfect circles for the orbits of the planets.

Copernicus used perfect circles for the orbits of the planets.

-all of the above

Diagrams like this one are commonly used in discussions of seasons and they can be quite useful. However, this diagram greatly exaggerates: -the size of Earth relative to the size of Earth's orbit around the Sun. -the size of the Sun relative to the size of Earth's orbit around the Sun. -the amount by which Earth's orbit differs from a perfect circle. -all of the above -only the first and third choices above

Shown here are astronomical objects located at different distances from Earth. Rank the objects based on their distances from Earth, from farthest to nearest.

Farthest: 1.Star on the far side of the Andromeda Galaxy 2.Star on the near side of the Andromeda Galaxy 3.Star on far side of Milky Way Galaxy 4.Star near center of Milky Way Galaxy 5. Orion Nebula 6.Alpha Centauri 7.Pluto 8.The Sun :Nearest

Consider again the diagrams from Parts A and B, which are repeated here. Again, assume that all the shaded areas have exactly the same area. This time, rank the segments of the comet's orbit based on the speed with which the comet moves when traveling from Point 1 to Point 2, from fastest to slowest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

From Parts A and B, you know that the comet takes the same time to cover each of the four segments shown, but that it travels greater distances in the segments that are closer to the Sun. Therefore, its speed must also be faster when it is closer to the Sun. In other words, the fact that that the comet sweeps out equal areas in equal times implies that its orbital speed is faster when it is nearer to the Sun and slower when it is farther away.

What practical value did astronomy offer to ancient civilizations? It helped them keep track of time and seasons, and it was used by some cultures for navigation. -It helped them understand our cosmic origins. -It helped them find uses for ancient structures like Stonehenge. -It allowed them to predict eclipses with great accuracy.

It helped them keep track of time and seasons, and it was used by some cultures for navigation.

Consider again the diagrams from Parts D and E, which are repeated here. Again, imagine that you observed the asteroid as it traveled for one week, starting from each of the positions shown. This time, rank the positions (A-D) from left to right based on how fast the asteroid is moving at each position, from fastest to slowest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Just as you found for the comet in Parts A through C, the asteroid must be traveling at a higher speed during parts of its orbit in which it is closer to the Sun than during parts of its orbit in which it is farther away. You should now see the essence of Kepler's second law: Although the precise mathematical statement tells us that an object sweeps out equal areas in equal times, the key meaning lies in the idea that an object's orbital speed is faster when nearer to the Sun and slower when farther away. This idea explains why, for example, Earth moves faster in its orbit when it is near perihelion (its closest point to the Sun) in January than it does near aphelion (its farthest point from the Sun) in July.

Which of the following paths could not be a real orbit for a planet around the Sun?

Kepler's first law tells us that the orbit of a planet must be an ellipse with the Sun at one focus. Therefore, the path that shows the Sun in the center of the ellipse, rather than at a focus, cannot be the real orbital path of a planet. (Note that the circular path is allowed because a circle is an ellipse in which both foci are at the center.)

This diagram shows a planet at four points in its orbit around the Sun. At which of the points shown is it traveling slowest in its orbit?

Kepler's second law tells us that a planet sweeps out equal areas in equal times as it moves along its orbit, which means it moves faster when it is closer to the Sun and slower when it is farther from the Sun. Point 4 is farthest from the Sun, which is why it is the point at which the planet moves slowest.

Each of the four diagrams below represents the orbit of the same asteroid, but each one shows it in a different position along its orbit of the Sun. Imagine that you observed the asteroid as it traveled for one week, starting from each of the positions shown. Rank the positions based on the area that would be swept out by a line drawn between the Sun and the asteroid during the one-week period, from largest to smallest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Kepler's second law tells us that the asteroid will sweep out equal areas in equal time intervals. Therefore, the area swept out in any one week period must always be the same, regardless of the asteroid's location in its orbit around the Sun.

Consider again the diagrams from Part A, which are repeated here. Again, assume that all the shaded areas have exactly the same area. This time, rank the segments of the comet's orbit from left to right based on the distance the comet travels when moving from Point 1 to Point 2, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Kepler's second law tells us that the comet sweeps out equal areas in equal times. Because the area triangle is shorter and squatter for the segments nearer to the Sun, the distance must be greater for these segments in order for all the areas to be the same.

When would you expect to see Venus high in the sky at midnight?

Never (For Venus to be high in the sky at midnight, it would have to be on the opposite side of our sky from the Sun. But that never occurs, because Venus is closer than Earth to the Sun. )

Rank the following items according to their size (diameter) from left to right, from largest to smallest.

Largest: The Universe The Local Supercluster The Local Group The Milky Way Galaxy Our Solar System The Sun Jupiter Earth :Smallest

The Milky Way and Andromeda galaxies are among a few dozen galaxies that make up our _______________.

Local Group

Consider the indicated events in the history of the universe that have helped make human life possible. Rank the events based on when they occurred, from longest ago to most recent. To rank items as equivalent, overlap them. Note: If two events occurred within seconds of each other, rank them as equivalent.

Longest Ago: 1. The Big Bang 1. The Universe begins to expand 2. Elements such as Carbon and Oxygen first exist 3. Nuclear fusion begins in the Sun 4. Earliest life on Earth 5. Dinosaurs go extinct 6. Earliest humans :Most Recent

Consider again the objects you ranked by distance in Part A. Suppose each object emitted a burst of light right now. Rank the objects from left to right based on the amount of time it would take this light to reach Earth, from longest time to shortest time.

Longest Time: 1.Star on the far side of the Andromeda Galaxy 2.Star on the near side of the Andromeda Galaxy 3.Star on far side of Milky Way Galaxy 4.Star near center of Milky Way Galaxy 5. Orion Nebula 6.Alpha Centauri 7.Pluto 8.The Sun :Shortest Time

Rank the following items that describe distances from longest distance (left) to shortest distance (right). (If two distances are equal, drag the second item on top of the first item.

Longest: 1 The distance from the Milky Way Galaxy to the Andromeda Galaxy 2 The distance from the Sun to the Milky Way Galaxy 3The Distance from Earth to Alpha Centauri 4 One Light Year 5 The Distance Across our Solar System to Neptune 5 The average distance from the Earth to the Sun :Shortest Be sure to remember that 1 AU is the average distance from Earth to the Sun of about 150 million kilometers, while 1 light-year is nearly 10 trillion kilometers. In other words, a light-year is a distance more than 60,000 times as large as an astronomical unit.

Two stars that are in the same constellation: -Must both be part of the same cluster of stars in space. -Must both have been discovered at about the same time. -May actually be very far away from each other.

May actually be very far away from each other

Our entire solar system orbits around the center of the __________ about once every 230 million years.

Milky Way Galaxy

Study this diagram, which shows why we see phases of Venus, as first observed by Galileo. When should we expect to see a full Venus in our night sky? -At midnight, when Venus is on the opposite side of its orbit from Earth. -Never. -At midnight, when Venus is on the same side of its orbit from Earth. -Only when Earth is at the opposite side of the Sun from what is shown in this diagram.

Never.

Consider again the diagrams from Part D, which are repeated here. Again, imagine that you observed the asteroid as it traveled for one week, starting from each of the positions shown. This time, rank the positions from left to right based on the distance the asteroid will travel during a one-week period when passing through each location, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Notice the similarity between what you have found here and what you found for the comet in Part B. Kepler's second law tells us any object will sweep out equal areas in equal times as it orbits the Sun, which means the area triangles are shorter and squatter when the object is nearer to the Sun, so that the object covers a greater distance during any particular time period when it is closer to the Sun than when it is farther away.

The great contribution of Tycho Brahe was to _________. -offer the first detailed model of a Sun-centered solar system, thereby beginning the process of overturning the Earth-centered model of the Greeks -observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion -discover four moons orbiting Jupiter, thereby lending strong support to the idea that Earth is not the center of the universe -discover that planets orbit the Sun in elliptical orbits with varying speed

Observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion

Galileo challenged the idea that objects in the heavens were perfect by _________. -observing sunspots on the Sun and mountains on the Moon -inventing the telescope -showing that heavy objects fall at the same rate as lighter objects -proving Kepler's laws were correct

Observing sunspots on the Sun and mountains on the Moon

Which of the following claims can be tested by scientific means? -Blue is the best color for walls. -God exists. -People born when the Sun is in the constellation of Leo are more financially successful than other people. -The final thoughts of Abraham Lincoln were about the fate of his country.

People born when the Sun is in the constellation of Leo are more financially successful than other people

Which of the following claims can be tested by scientific means? -The final thoughts of Abraham Lincoln were about the fate of his country. -God exists. -Blue is the best color for walls. -People born when the Sun is in the constellation of Leo are more financially successful than other people.

People born when the Sun is in the constellation of Leo are more financially successful than other people.

Galileo observed all of the following. Which observation offered direct proof of a planet orbiting the Sun? -Four moons of Jupiter. -Patterns of shadow and sunlight near the dividing line between the light and dark portions of the Moon's face -The Milky Way is composed of many individual stars. -Phases of Venus

Phases of Venus

Which of the following is not consistent with the major hallmarks of science? -Science consists of proven theories that are understood to be true explanations of reality. -Scientific explanations should be based solely on natural causes. -Science progresses through the creation and testing of models that explain observation as simply as possible. -A scientific model must make testable predictions.

Science consists of proven theories that are understood to be true explanations of reality.

What, if anything, is wrong with the planetary orbit shown? -The Sun is not at one focus, as Kepler's first law requires. -The orbital path violates Kepler's third law. -There is nothing wrong with this orbit; it is fine as shown. -The shape of the orbit is not an ellipse, as Kepler's first law requires.

The Sun is not at one focus, as Kepler's first law requires. (Because this ellipse is not a perfect circle, neither of its two foci are at the center of the ellipse. Kepler's first law tells us that the Sun must be located at one of the two foci.)

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? -The asteroid shares the same orbit around the Sun as Earth. -The asteroid's average (semimajor axis) distance from the Sun is 1AU. -The asteroid has the same perihelion distance as Earth. -The asteroid will eventually collide with Earth. -The asteroid has a more eccentric orbit than Earth.

The asteroid's average (semimajor axis) distance from the Sun is 1AU.

How did the Ptolemaic model explain the apparent retrograde motion of the planets? -The planets resided on giant spheres that sometimes turned clockwise and sometimes turned counterclockwise. -The planets sometimes stopped moving and then reversed to move backward along their circular orbits. -The model showed that apparent retrograde motion occurs as Earth passes by another planet in its orbit of the Sun. -The planets moved along small circles that moved on larger circles around the Earth.

The planets moved along small circles that moved on larger circles around the Earth.

Assume you knew nothing else about the planets but what is shown in this diagram. What could you conclude? -Earth takes less than a third as long to orbit the Sun as Mars. -The outer planets are more massive than the inner planets. -The square of a planet's period in years is equal to the cube of its average distance from the Sun in AU. -Saturn orbits the Sun faster than any other planet.

The square of a planet's period in years is equal to the cube of its average distance from the Sun in AU. (This is Kepler's third law. The graph illustrates it because it shows a straight line relationship between the cube of average distance (see the label on the horizontal axis) and the square of period (see the label on the vertical axis).)

Which of the following best describes a set of conditions under which archaeoastronomers would conclude that an ancient structure was used for astronomical purposes? -They find that, looking out from the center of the building, there are two windows that align with the rise and set points of two bright stars. -The structure has the same dome shape as modern astronomical observatories. -The structure consists of lines in the desert that make patterns visible only from high above. -The structure has holes in the ceiling that allow viewing the passage of constellations that figure prominently in the culture's folklore, and many other structures built by the same culture have ceiling holes placed in the same way.

The structure has holes in the ceiling that allow viewing the passage of constellations that figure prominently in the culture's folklore, and many other structures built by the same culture have ceiling holes placed in the same way.

You've now seen that Earth's varying distance cannot be the cause of our seasons. So 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. -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. -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. -The seasons are caused by variation in the amount of rainfall (or snowfall) in different places at different times of year.

The tilt of Earth's axis causes different portions of the Earth to receive more or less direct sunlight at different times of year.

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? -Summer occurs when Earth is closer to the Sun and winter occurs when Earth is farther from the Sun. -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. -The variation in Earth-Sun distance over the course of each year has virtually no effect on the seasons.

The variation in Earth-Sun distance over the course of each year has virtually no effect on the seasons.

the meridian

This diagram represents a person's local sky. What does the red semicircle represent? -the horizon -the celestial equator -the meridian -the zenith

-the celestial equator

This diagram represents a simplified model of the celestial sphere. The unlabeled circle that is highlighted in purple represents: -the ecliptic -the meridian -the spring equinox -the celestial equator

-several months

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: -about 3 nights -one full night -about one hour -several months

All of the following statements are true. Which one can be explained by Kepler's third law? -All the planets orbit the Sun in nearly the same plane. -Venus orbits the Sun at a faster orbital speed than Earth. -Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun. -The Sun is not in the precise center of Saturn's orbit. -Earth is slightly closer to the Sun in January than in July.

Venus orbits the Sun at a faster orbital speed than Earth.

All the following statements are true. Which one follows directly from Kepler's third law (p2 = a3)? -Venus takes longer to rotate than it does to orbit the Sun. -Venus orbits the Sun at a slower average speed than Mercury. -Venus is more massive than Mercury. -Venus has a thicker atmosphere than Mercury.

Venus orbits the Sun at a slower average speed than Mercury.

Listed following are locations and times at which different phases of the Moon are visible from Earth's Northern Hemisphere. Match these to the appropriate moon phase.

Waxing Crescent Moon: -Sets 2-3 hours after the sun sets -Visible near western horizon about an hour after sunset Waning Crescent Moon: -Occurs about three days before new moon -Visible near eastern horizon just before sunrise Full Moon: -Rises at about the same time the sun sets -Occurs 14 days after the new moon -Visible due south at midnight

Imagine for a moment that despite all the evidence, Earth actually is not rotating and orbiting the Sun. Which of these hypothetical observations (none of them are real) would be inconsistent with our Sun-centered view of the solar system? -We discover an Earth-sized planet orbiting the Sun beyond the orbit of Pluto. -We find that we are unable to measure any parallax for a distant galaxy. -We discover a small planet beyond Saturn that rises in the west and sets in the east each day. -We discover that the universe is actually contracting, not expanding.

We discover a small planet beyond Saturn that rises in the west and sets in the east each day.

In Ptolemy's Earth-centered model for the solar system (not shown), Venus always stays close to the Sun in the sky and, because it always stays between Earth and the Sun, its phases range only between new and crescent. The following statements are all true and were all observed by Galileo. Which one provides evidence that Venus orbits the Sun and not Earth?

We sometimes see gibbous (nearly but not quite full) Venus.

Stellar parallax occurs in much the same way as parallax on Earth, with greater parallax for stars that are nearer. Explore the Parallax Angle animation, and watch how the motion of the star changes in the "View from Earth" window. Which statement best summarizes why stellar parallax occurs? -Nearby stars move in tiny circles as Earth orbits the Sun. -We view nearby stars from different positions on Earth as Earth rotates on its axis. -Nearby stars move at higher speeds relative to the Sun than more distant stars. -We view nearby stars from different positions in Earth's orbit at different times of year.

We view nearby stars from different positions in Earth's orbit at different times of year.

-3

Which position in this diagram represents Earth at the beginning of spring for the Southern Hemisphere? -3 -2 -4 -1

Which of the following was NOT observed by Galileo? -four moons orbiting Jupiter -mountains and valleys on the Moon -phases of Venus. -stellar parallax

stellar parallax

Consider again the set of observations from Part A. This time, classify each observation according to whether it is consistent with only the Earth-centered model, only the Sun-centered model, both models, or neither model. (Note that an observation is "consistent" with a model if that model offers a simple explanation for the observation.)

[Earth-centered only] - a planet beyond Saturn rises in west, sets in east [Sun-centered only] - Mercury goes through a full cycle of phases - positions of nearby stars shift slightly back and forth each year [Both models] - stars circle daily around north or south celestial pole - moon rises in east, sets in west each day - a distant galaxy rises in east, sets in west each day [Neither model] - we sometimes see a crescent Jupiter

Let's start with an example from history. Listed below are a series of claims regarding United States President John F. Kennedy (1917-1963). Classify each statement according to whether or not it is falsifiable.

[Falsifiable:could be proven false] - Kennedy was the 35th president of the United States - Kennedy died from a bullet in his brain [Not falsifiable:could not be proven false] - Kennedy's death was the will of God - The murder of John F. Kennedy was an act of evil - If he'd lived, Kennedy would have ended the Vietnam War - Kennedy's murder was orchestrated by an undetectable shadow government of the United States

Let's now consider possible scientific claims. Recall that a scientific claim is falsifiable if it could in principle be shown to be false by observations or experiments, even if those observations or experiments have not yet been performed. Classify each claim according to whether or not it is falsifiable.

[Falsifiable:could be proven false] - The chemical content of the universe is mostly hydrogen and helium - Earth is at the center of the solar system - The Sun is at the center of the solar system - The observable universe contains approximately 100 billion galaxies [Not falsifiable:could not be proven false] - We are all playthings in a computer program created by advanced aliens - The laws of nature are magnificent and beautiful - The universe was created by God

Consider the following observations. Classify each observation based on whether it is a real observation (a true statement of something we can actually see from Earth) or one that is not real (a statement of something that does not really occur as seen from Earth).

[Real:true statements] - Mercury goes through a full cycle of phases - Moon rises in east, sets in west each day - stars circle daily around north or south celestial pole - positions of nearby stars shift slightly back and forth each year - a distance galaxy rises in east, sets in west each day [Not real:false statements] - we sometimes see a crescent Jupiter - a planet beyond Saturn rises in west, sets in east

What do we mean by a geocentric model of the universe? -a model designed to explain what we see in the sky while having Earth orbit the Sun -a model designed to explain what we see in the sky while having Earth located in the center of the universe -the name given to sphere-shaped models that show all the constellations as they appear in our sky on the celestial sphere -a model of the Milky Way Galaxy that has our solar system located at its center

a model designed to explain what we see in the sky while having Earth located in the center of the universe

What was the Ptolemaic model? -a Sun-centered model of planetary motion published by Ptolemy -the Earth-centered model of the cosmos in which Earth was surrounded by seven perfect spheres, one each for the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn -the first scientific model to successfully predict solar and lunar eclipses -an Earth-centered model of planetary motion published by Ptolemy

an Earth-centered model of planetary motion published by Ptolemy

1. 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) __________.

annular eclipse

Earth orbits in the shape of a/an ________ around the Sun.

ellipse

Earth is located at one ______ of the Moon's orbit.

focus

The Sun appears to rise and set in our sky because Earth _________ once each day.

rotates

The mathematical form of Kepler's third law measures the period in years and the ____ in astronomical units (AU).

semimajor axis

Anyone looking from the night side of Earth can, in principle, see a(n) ___________.

total lunar eclipse

A(n) _________ can occur only when the Moon is new and has an angular size larger than the Sun in the sky.

total solar eclipse

A partial lunar eclipse begins when the Moon first touches Earth's __________.

umbra

On average, galaxies are getting farther apart with time, which is why we say our ________ is expanding.

universe