AST 111

Start at the beginning of the Moon Orbit video, 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 __________.

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 _________.

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?

just a few hours before midnight on December 31

Sort each item into the correct bin based on whether it describes lunar eclipses or solar eclipses.

lunar eclipses: - 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 solar eclipses - occurs when the Moon comes directly between Earth and the Sun - can occur only at new moon - can be seen only along a relatively narrow path on Earth - occurs when the Moon's shadow falls on Earth

A total solar eclipse can only happen during what lunar phase?

new

Again consider the position of the Moon shown in part A. How much of the Moon's surface is covered by Earth's shadow?

none

Suppose you live at a mid-latitude in the Southern Hemisphere (such as in Australia, New Zealand, Chile, or South Africa). When will you have 12 hours of daylight and 12 hours of darkness?

on both the March and September equinoxes

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?

at the two points at the top and bottom

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?

b - moon over arrow

Astronomers infer that the universe is expanding because distant galaxies all appear to _________.

be moving away from us, with more distant ones moving faster

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?

because the line of nodes gradually moves around the Moon's orbit

Again consider the position of the Moon shown in part A. What does the Moon look like in our sky at this time?

c the crescent shape

Which photo shows what the Moon looks like when it is in the position shown in the following moon phase diagram?

c the full 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. In this hypothetical situation, approximately how many solar eclipses would occur each year?

12

Based on observations of the universal expansion, the age of the universe is about _________.

14 billion years

In reality, the Moon's orbit about Earth is tilted (by about 5°) with respect to Earth's orbit about the Sun. As a result, the actual number of solar eclipses that occur each year is approximately _____.

2

Today, astronomers can detect and measure stellar parallax for thousands of the nearest stars, providing us with direct evidence that Earth really does orbit the Sun. Moreover, as the Parallax Angle animation shows (return to the main "Parallax" screen, and select the "Parallax and Distance" button), these measurements allow us to calculate distances to these relatively nearby stars. If we hope to use parallax to measure distances to even more-distant stars, which of the following telescopes would be most useful?

A telescope that orbits the Sun in the outer solar system

Place each statement in the correct bin corresponding to whether it represents 1 astronomical unit (1 AU), 1 light-year, or neither of those.

AU BIN: about 150 million kilometers, Earth's average distance from the Sun, Jupiter lies about 5.2 of these from the Sun 1 LY bin: the distance light travels in 1 year about, 10 trillion kilometers, the star Sirius lies about 8 of these from the Sun NEITHER: Mars's average distance from the Sun the diameter of Earth

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

Which of the following is not a general difference between a planet and a star?

All planets are made of rock and all stars are made of gas.

When is the next opportunity to see a total solar eclipse in the United States?

April 8, 2024

Drag words from the left to the blanks at the right to complete the sentence correctly.

At most times, Mars appears to move eastward relative to the stars. The exceptions are during its periods of apparent retrograde motion, when Mars appears to move westward relative to the stars.

What do we mean when we say that the universe is "expanding"?

Average distances between galaxies are increasing with time.

Why do the patterns of the stars in our sky look the same from year to year?

Because the stars in the constellations are so far away.

Complete the sentence correctly by dragging a word representing Mars's appearance to the first blank and a time of day to the second blank.

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.

The table in the video shows you the speeds of Raisins 1, 2, and 3 as measured from the Local Raisin. Suppose instead that 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

Why will total solar eclipses no longer be possible after about 600 million years from now?

The Moon will have moved too far from Earth for it to fully block the Sun.

What do astronomers mean by the "Big Bang"?

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

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: winter, spring, fall summer Farthest:

A typical galaxy is a _________.

collection of millions or billions of stars, bound together by gravity and orbiting a common center

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?

d You can tell this is third quarter, rather than first quarter, because it is the position where the Moon has traveled 3/4 of the way around its from the new moon position.

As seen from Earth, the Sun appears to follow the annual path that we call the __________ around the celestial sphere.

ecliptic

Based on their inability to detect stellar parallax, the ancient Greeks concluded that ______

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

Suppose you see a first quarter moon in your evening sky. How will the Moon's appearance change over the next few days?

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.

Which statement about motion in the universe is not true?

The mysterious "dark matter" is the fastest-moving material in the universe.

When we look at an object that is 1,000 light-years away we see it _________.

as it was 1,000 years ago

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 2 ½ million years ago

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?

at the point on the far left

Based on their inability to detect stellar parallax, the ancient Greeks concluded that _________.

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

Play the Moon Orbit video through to 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?

everywhere along its orbit

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?

exactly half

Suppose you see a moon that is half bright and half dark in your early evening sky. Then you are seeing a __________ moon.

first quarter

On the cosmic calendar, which compresses the history of the universe into a single year, about when did Earth form?

in early September

On the cosmic calendar, which compresses the history of the universe into a single year, about when did life arise on Earth?

in september

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?

rise: about midight; set: about noon

On a scale in which the distance from Earth to the Sun is about 15 meters, the distance from Earth to the Moon is _________.

small enough to fit within your hand

Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case _________.

we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2

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

- Earth is too big compared to the Moon's orbit. - The Moon is too big compared to its orbit. - The astronaut is too big compared to the Moon. - The Moon is too big compared to Earth.

Which of the following statements are true about summer compared to winter?

- Temperatures tend to be warmer in summer. - You have more daylight and less darkness in summer. - The Sun follows a longer and higher path through your sky in summer.

Which of the following statements about phases of the Moon are true? Select all that apply

- 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, we see only the "night" side of the Moon -at new moon, the half of the Moon facing the Sun is fully illuminated

Match the words in the left-hand column to the appropriate blank in the sentences in the right-hand column. Use each word only once.

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. 2. Anyone looking from the night side of Earth can, in principle, see a(n) total lunar eclipse. 3. 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. 4. A(n) total solar eclipsecan occur only when the Moon is new and has an angular size larger than the Sun in the sky. 5. A partial lunar eclipse begins when the Moon first touches Earth's umbra. 6. A point at which the Moon crosses Earth's orbital plane is called a(n) node.

Use the procedure shown in the video to determine the approximate rise, highest point, and set times for different phases of the Moon, then complete the following sentences.

1. A waxing gibbous moon rises at about 3pm, reaches its highest point in the sky at about 9pm, and sets around 3am. 2. A waxing crescent moon rises at about 9am, reaches its highest point in the sky at about 3pm, and sets around 9pm. 3. A first quarter moon rises at about noon, reaches its highest point in the sky at about sunset, and sets around midnight. 4. A new moon rises at about sunrise, reaches its highest point in the sky at about noon, and sets around sunset 5. A waning gibbous moon rises at about 9pm, reaches its highest point in the sky at about 3am, and sets around 9am 6. A full moon rises at about sunset, reaches its highest point in the sky at midnight, and sets around sunrise.

The following statements describe ways in which the analogy might apply to the real universe. Which statements are correct?

1. 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. 2. The average distance increases with time both between raisins in the cake and between galaxies in the universe. 3. The raisins stay roughly the same size as the cake expands, just as galaxies stay roughly the same size as the universe expands.

Which of the following are real motions of our "spaceship Earth"?

1. Earth orbits the Sun. 2. Earth moves with the Sun on an orbit around the center of the Milky Way galaxy. 3. Earth and our solar system moves with the Milky Way galaxy relative to other galaxies in our Local Group.

Match the words in the left-hand column to the appropriate blank in the sentences in the right-hand column. Use each word only once

1. Our entire solar system orbits around the center of the Milky Way Galaxyabout once every 230 million years. 2. The Milky Way and Andromeda galaxies are among a few dozen galaxies that make up our Local Group. 3. The Sun appears to rise and set in our sky because Earth rotatesonce each day. 4. You are one year older each time Earth orbitsabout the Sun. 5. On average, galaxies are getting farther apart with time, which is why we say our universeis expanding. 6. Our solar systemis moving toward the star Vega at about 70,000 km/hr.

Observations of stellar parallax therfore provide direct evidence that:

1. earth orbits the sun 2. some stars are more distant than others

What conditions must exist for a lunar eclipse to occur?

1. it must be a full moon 2. the Moon must be passing through Earth's orbital plane

What conditions must exist for a solar eclipse to occur?

1. the Moon must be passing through Earth's orbital plane 2. It must be a new moon

Each of the following figures shows Earth with a different axis tilt. (Assume that Earth's rotation period is unchanged.) Each also shows a person located in Florida (not to scale). Rank the figures based on how much time the person spends in daylight during a 24-hour period, from most to least.

1. tilt 23 1/2 (with the person standing on the left) 2. tilt 0 3. Tilt 23 1/2 person standing closer to the middle 4. tilt 45 5. tilt 90

The following figures are the same as those from Part A. This time, consider the seasonal differences that occur as Earth orbits the Sun with the different axis tilts. Rank the figures on the basis of the seasonal temperature differences you would expect between summer and winter, from the one with the most extreme seasonal differences to the one with the least extreme. To rank items as equivalent, overlap them

1. tilt 90 2. 45 3. 23 1/3 4. 0

Shown here are six galaxies, each labeled with its approximate distance from Earth. Rank the galaxies from left to right based on the amount of time it has taken their light to travel to Earth, from the longest time to the shortest time.

10 Bil, 5 bil, 2 bil, 800 mil, 230 mil, 70 mil

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?

4 Now that you've identified the correct position, think about the time for this person.

Consider again the galaxies you ranked in Part A. This time, rank them from left to right based on the age of the universe at the time these galaxies emitted the light we receive from them today, from oldest (closest to today) to youngest (furthest back in time

70 mil, 230 mil, 800 mil, 2 bil, 5 bil, 10 bil

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.

The Sun rises and sets each day because

Earth rotates once each day

What is the basic reason that we have seasons on Earth?

Earth's axis is tilted relative to the ecliptic plane.

Which of the following lies in the ecliptic plane?

Earth's orbital path around the Sun

How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects?

Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth.

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?

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

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?

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

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

FARTHEST: 1. star on the far side of the andromita galexy, 2. star on the near side of the andromita galexy, star on the far side of the milkey way galexy, star near the center of the milkey way galexy, oron nebula, Alpha Centrui, pluto, the sun

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.

FARTHEST: 1. star on the far side of the andromita galexy, 2. star on the near side of the andromita galexy, star on the far side of the milkey way galexy, star near the center of the milkey way galexy, oron nebula, Alpha Centrui, pluto, the sun

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 andromita galexy, 2. star on the near side of the andromita galexy, star on the far side of the milkey way galexy, star near the center of the milkey way galexy, oron nebula, Alpha Centrui, pluto, the sun

How are galaxies important to our existence?

Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.

Which of the following best summarizes the reason we see phases of the Moon?

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.

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?

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.

Complete the sentence correctly by dragging words representing something you can measure to the first blank and a time period to the second blank.

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.

Relative to the age of the universe, how old is our solar system?

It is about one-third the age of the universe.

What happens to Earth's axis as we orbit around the Sun over the course of each year?

It remains pointed in the same direction at all times.

What is special about the June solstice?

It's the day on which the Northern Hemisphere receives its most direct sunlight.

Because we live in an expanding universe, distant galaxies are farther away from us today than they were when the light we see from them started on its journey to us. So what do we mean when we say that a galaxy is 7 billion light-years away?

Its light has taken 7 billion years to reach us.

Which of the following planets has essentially no seasons at all?

Jupiter (axis tilt = 3.1°)

Regarding the history of the universe, which of the following is true?

Key elements of which Earth and life are made, including carbon, oxygen, and iron, did not exist when the universe was born and were created later in stars.

Rank the following objects from largest to smallest.

LG: Galexy, Solar system, sun, earth SM

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?

Mars (axis tilt = 25.2°)

Match the choices in the left-hand column to the appropriate blank in the in the right-hand column. Use each choice only once.

Mars is about 1.5 AU from the Sun. Jupiter is about 5 AU from the Sun. The star Sirius is about 8 light-years from the Sun. The diameter of the Milky Way Galaxy is about 100,000 light-years. The distance from Earth to the Moon is less than 0.01 AU.

Using the ideas discussed in your text, in what sense are we "star stuff"?

Nearly every atom from which we are made was once inside of a star.

Could we see a galaxy that is 20 billion light-years away? (Assume that we mean a "lookback time" of 20 billion years.)

No, because it would be beyond the bounds of our observable universe.

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?

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

How long does it take the Earth to complete one orbit around the Sun?

One year

Match the correct names for regions of eclipse shadows to their descriptions.

Partial shadow (penumbra): the larger, surrounding region of an object's shadow in which light from the Sun is only partially blocked Full shadow (umbra): the dark, central region of an object's shadow, in which light from the Sun is fully blocked

Note that an observer located at the Local Raisin would see Raisins 1, 2, and 3 all move away from her during the video. What would an observer located at Raisin 2 see?

Raisin 1 and Raisin 3 both move away from her.

Where is our solar system located within the Milky Way Galaxy?

Roughly halfway between the center and the edge of the visible disk of the galaxy

If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy?

Several thousand years

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.

TIED: a. the universe began to expand, the big bang, 2. elements such as carbon and oxygen began to exist, nuclear fission begins in the sun, earliest life on earth, dinosours go extinct, earliest humans

As you play the Moon Orbit video, notice how the arrows representing the Sun's rays are at first spread apart but become parallel as the video zooms in on the Moon's orbit. Why do the Sun's rays become parallel at the end of the video?

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.

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.

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?

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

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

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.)

The distance from the milkey way galexy to the andromita galexy, the distance from the Sun to the center of the Milky Way Galaxy, the distance from Earth to Alpha Centauri, one light year, the distance across our solar system (to Neptune), TIED ARE; the average distance from Earth to the Sun, and one AU

Suppose we observe a galaxy that is 13 billion light-years away. Which of the following can we conclude?

The galaxy formed before the universe was 1 billion years old

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?

The photographer is moving, but the man and the trees are staying still.

On the main screen of the interactive figure, select "Parallax", then select the "Introduction to Parallax" button. Click the play button to watch the animation, 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 is moving, but the person being photographed and the trees are staying still.

What is the ecliptic plane?

The plane of Earth's orbit around the Sun

Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?

The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart.

Which of the following best describes what we mean by the universe?

The sum total of all matter and energy

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

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?

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

In what sense are telescopes like time machines?

They allow us to see distant objects as they were long in the past.

In January, Earth's rotation axis points in the direction of the star Polaris. Where does it point in July?

Toward the star Polaris

Which of the following planets should have the most extreme seasons?

Uranus (axis tilt = 97.9°)

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.)

We always see the same face of the Moon.

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.

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

Stellar parallax occurs in much the same way as parallax on Earth, with greater parallax for stars that are nearer. Return to the main "Parallax" screen, and from here select the "Stellar Parallax" button, and watch how the motion of the star changes in the "View from Earth" window. Which statement best summarizes why stellar parallax occurs?

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

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 an extremely distant galaxy that is moving toward us.

Which of the following has your "cosmic address" in the correct order?

You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe

The number of stars in the Milky Way Galaxy is approximately _________.

a few hundred billion

What is an annular eclipse?

a solar eclipse in which the Moon does not appear large enough to fully block the Sun

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?

a telescope on Mars

Which of the following accurately describe an eclipse season?

a. During an eclipse season, there will be a lunar eclipse at full moon. b. During an eclipse season, there will be a solar eclipse at new moon. c. An eclipse season occurs when the nodes of the Moon's orbit are lined up with Earth and the Sun.

According to current scientific estimates, when did the Big Bang occur?

about 14 billion years ago

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

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.

summer, fall spring winter

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)?

sunrise

The term observable universe refers to _______

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

Our solar system consists of _________.

the Sun and all the objects that orbit it

An astronomical unit (AU) is _________.

the average distance between Earth and the Sun

The total number of stars in the observable universe is about _________.

the same as the number of grains of sand on all the beaches on Earth

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

the universe, the local supercluster, the local group, the milky way galaxy, our solar system, the sun, jupiter, earth

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

their distances and speeds

Approximately how often do eclipse seasons occur?

twice a year

If we imagine the history of the universe compressed into one year, with the present as the stroke of midnight at the very end of that year, dinosaurs became extinct _________.

yesterday morning