Astronomy How is the geocentric theory different from the heliocentric theory?

AstronomyAstronomyHow is the geocentric How is the geocentric theory different from theory different from

the heliocentric theory? the heliocentric theory?

Terms Part 1Terms Part 1 UniverseUniverse Big BangBig Bang GalaxiesGalaxies NebulaNebula OrbitsOrbits Solar SystemSolar System

Geocentric Geocentric TheoryTheory

Heliocentric Heliocentric TheoryTheory

GalileoGalileo CopernicusCopernicus

How is the geocentric theory different How is the geocentric theory different from the heliocentric theory? from the heliocentric theory?

What do most scientists What do most scientists say produced the say produced the universe?universe?

Compare and Contrast Compare and Contrast the geocentric theory the geocentric theory and the heliocentric and the heliocentric theory.theory.

Who was Copernicus and Who was Copernicus and what did he propose that what did he propose that was later supported by was later supported by observations made by observations made by Galileo?Galileo?

The Formation of Our Solar SystemThe Formation of Our Solar System

Most scientists believe that the Most scientists believe that the universeuniverse began began about 13.5 billion years ago in a great about 13.5 billion years ago in a great explosion, called the explosion, called the Big BangBig Bang..

Later, the space material from the explosion Later, the space material from the explosion formed the first stars.formed the first stars.

These stars were drawn together by gravity to These stars were drawn together by gravity to produce produce family of stars, called family of stars, called galaxiesgalaxies..

A A galaxygalaxy is a large group of stars, gas, is a large group of stars, gas, and dust held together by gravityand dust held together by gravity

There are three types of galaxies …There are three types of galaxies …

Elliptical, Irregular, and SpiralElliptical, Irregular, and Spiral

Can you guess which one is which?Can you guess which one is which?

Spiral Galaxy Spiral Galaxy – a central – a central bulge of older stars bulge of older stars and arms that stretch and arms that stretch outward like a wheeloutward like a wheel

Elliptical Galaxy – has an oval shape with a bright center.

Irregular Galaxy – Galaxies that are not Irregular Galaxy – Galaxies that are not spiral or elliptical are considered spiral or elliptical are considered irregularirregular

The Formation of Our Solar The Formation of Our Solar SystemSystem

Most scientists believe that about 5 billion years Most scientists believe that about 5 billion years agoago, a gigantic cloud of gases and dust, called a , a gigantic cloud of gases and dust, called a nebulanebula, was disturbed and began to spin., was disturbed and began to spin.

Something disturbed the nebula causing it to spinSomething disturbed the nebula causing it to spin

As it spun, material clumped together. Intense As it spun, material clumped together. Intense heat and pressure created heat and pressure created our sunour sun

Grains of dust surrounding the sun collided over Grains of dust surrounding the sun collided over and over to form planets, moons, and comets in and over to form planets, moons, and comets in our solar systemour solar system

The Formation of Our Solar The Formation of Our Solar System,System,

These These objects revolve around the sun in paths objects revolve around the sun in paths called called orbitsorbits..

Centuries ago, Centuries ago, most people thought Earth was the most people thought Earth was the center of the solar system, not the sun. This theory center of the solar system, not the sun. This theory is called the is called the geocentric theorygeocentric theory..

The idea that the sun is the center of the solar The idea that the sun is the center of the solar system is called the system is called the heliocentric theoryheliocentric theory..

CopernicusCopernicus was an astronomer. He suggested was an astronomer. He suggested that the sun, not Earth, was the center of the solar that the sun, not Earth, was the center of the solar system.system.

Geocentric TheoryGeocentric Theory

What does the prefix geo- mean?What does the prefix geo- mean?

What does –centric mean?What does –centric mean?

What do you think geocentric What do you think geocentric means? means?

Geocentric TheoryGeocentric Theory GeocentricGeocentric

means earth means earth centered.centered.

Ptolemy Ptolemy developed the developed the geocentric geocentric theory theory

A long time ago A long time ago people thought people thought Earth was the Earth was the center of our center of our solar system and solar system and everything everything revolved around revolved around itit

Heliocentric TheoryHeliocentric Theory

What does the prefix helio- mean?What does the prefix helio- mean?

What do you think heliocentric means?What do you think heliocentric means?

Heliocentric TheoryHeliocentric Theory

• HeliocentricHeliocentric means means sun centered sun centered

• Copernicus was the Copernicus was the first person to suggest first person to suggest that the sun was the that the sun was the center of the solar center of the solar systemsystem

• Galileo used Galileo used telescopes to make telescopes to make observations that the observations that the sun was the center of sun was the center of the solar systemthe solar system

The Formation of Our Solar The Formation of Our Solar System, System,

Galileo Galileo invented a telescope and invented a telescope and discovered 4 moons revolving Jupiter.discovered 4 moons revolving Jupiter.

He concluded that not everything in the He concluded that not everything in the solar system revolved around Earth.solar system revolved around Earth.

Galileo found that Venus goes through Galileo found that Venus goes through phases like those of the moon, as phases like those of the moon, as predicted by Copernicus.predicted by Copernicus.

Galileo reasoned that this could happen Galileo reasoned that this could happen only if Venus revolved around the sun, not only if Venus revolved around the sun, not around Earth.around Earth.

Quick CheckQuick Check

What did the geocentric theory What did the geocentric theory state?state?

A.A. The sun is at the center of the solar The sun is at the center of the solar systemsystem..

B.B. Earth is at the center of the solar system.Earth is at the center of the solar system.

C.C. The universe began with a great The universe began with a great explosion.explosion.

D.D. The earth revolves around a moon.The earth revolves around a moon.


What object is the largest?What object is the largest?

A. EarthA. Earth

B. the sunB. the sun

C. the Milky Way GalaxyC. the Milky Way Galaxy

D. a starD. a star


Which happened MOST recently?Which happened MOST recently?

A. the formation of the universeA. the formation of the universe

B. the formation of the solar systemB. the formation of the solar system

C. the formation of the sunC. the formation of the sun

D. the formation of the Milky Way GalaxyD. the formation of the Milky Way Galaxy


The solar system is thought to The solar system is thought to be formed from which of the be formed from which of the following objects?following objects?

A. the sunA. the sun

B. the Milky Way GalaxyB. the Milky Way Galaxy

C. a nebulaC. a nebula

D. the universeD. the universe


What was the FIRST discovery made What was the FIRST discovery made by Galileo that supported Copernicus’ by Galileo that supported Copernicus’ idea that the sun, not the earth, was idea that the sun, not the earth, was at the center of the solar system?at the center of the solar system?

A. the discovery of JupiterA. the discovery of Jupiter

B. the discovery of some of Jupiter’s moonsB. the discovery of some of Jupiter’s moons

C. The discovery of the phases of VenusC. The discovery of the phases of Venus

D. the discovery of the telescopeD. the discovery of the telescope


What hypothesis was proposed by Nicolas What hypothesis was proposed by Nicolas Copernicus that was later supported by Copernicus that was later supported by observations made by Galileo?observations made by Galileo?

a.a. The universe began with a Big Bang.The universe began with a Big Bang.

b.b. Earth is the center of the solar system.Earth is the center of the solar system.

c.c. The sun is the center of the solar The sun is the center of the solar system.system.

d.d. The solar system is about 4.5 billion The solar system is about 4.5 billion years old.years old.


From the oldest event to the most From the oldest event to the most recent event in the formation of the recent event in the formation of the solar system, which is the correct solar system, which is the correct sequence? sequence?

a. nebula, Big Bang, suna. nebula, Big Bang, sun

b. Big Bang, nebula, sunb. Big Bang, nebula, sun

c. sun, nebula, Big Bangc. sun, nebula, Big Bang

d. Big Bang, sun, nebulad. Big Bang, sun, nebula


To what hypothesis does the Big Bang refer?To what hypothesis does the Big Bang refer?

a. an explanation of how the universe a. an explanation of how the universe beganbegan

b. an explanation of how the Milky Way b. an explanation of how the Milky Way Galaxy beganGalaxy began

c. an explanation of how the solar system c. an explanation of how the solar system beganbegan

d. an explanation of how Earth begand. an explanation of how Earth began

The Position of the The Position of the Solar SystemSolar System

TermsTerms Light year = 1 light year is the Light year = 1 light year is the

distance light travels in a year.distance light travels in a year. 1 light year = 9.5 trillion km1 light year = 9.5 trillion km

Astronomical unit = 1 astronomical Astronomical unit = 1 astronomical unit is the average distance between unit is the average distance between the sun and Earth the sun and Earth (150,000,000 km).(150,000,000 km).

What is the position or location of What is the position or location of our solar system?our solar system?

What is a light year?What is a light year?

Give a detailed Give a detailed description of the description of the Milky Way Galaxy.Milky Way Galaxy.

Where is our solar Where is our solar system located?system located?

What is an What is an astronomical unit? astronomical unit?

778,000,000What do you think this number

means?

money?

# of People?

Baseball players salary?

Number of hairs on your head?

778,000,000 778,000,000 kilometerskilometers

is the distance is the distance from thefrom the

sun to Jupiter!sun to Jupiter!

1 meter = 150,000,000km1 meter = 150,000,000km

EX: EX: 378,000,000 km 378,000,000 km = 2.8 = 2.8

150,000,000150,000,000

You need 2.8 metersYou need 2.8 meters

Measuring SpaceMeasuring Space

A A light year light year is the distance light is the distance light travels in 1 year travels in 1 year it is it is approximately 9.5 trillion kilometersapproximately 9.5 trillion kilometers

An An Astronomical Unit (AU) Astronomical Unit (AU) is the is the average distance between Earth and average distance between Earth and the sun the sun one AU is approximately one AU is approximately 150,000,000 kilometers150,000,000 kilometers

The Position of the Solar System The Position of the Solar System

A light year is the distance light travels in a A light year is the distance light travels in a yeayear. The most distant objects observed from r. The most distant objects observed from Earth are about 13.6 billion light years away. Earth are about 13.6 billion light years away. One (1) light year = 9.5 trillion km.One (1) light year = 9.5 trillion km.

Galaxies come in all sizes and shapes. Galaxies come in all sizes and shapes. The The Milky Way Galaxy is shaped like a giant Milky Way Galaxy is shaped like a giant flattened disc with a bulge in the middle.flattened disc with a bulge in the middle.

Spiral arms spin out into space from the Milky Spiral arms spin out into space from the Milky Way Galaxy’s center.Way Galaxy’s center.

The Position of the Solar System The Position of the Solar System

The Milky Way is about 100,000 light The Milky Way is about 100,000 light years (9.5 million trillion km) in years (9.5 million trillion km) in diameter.diameter.

It is between 1000 to 3000 light It is between 1000 to 3000 light years (9.3 million billion km to 31.0 years (9.3 million billion km to 31.0 million billion km) thick.million billion km) thick.

It is thickest at the center.It is thickest at the center.

The Position of the Solar SystemThe Position of the Solar System

Our solar system is located in one of the galaxy’s Our solar system is located in one of the galaxy’s outer arms.outer arms.

The sun is about 30,000 light years away from The sun is about 30,000 light years away from the center of the galaxy.the center of the galaxy.

It takes our solar system about 240 million years It takes our solar system about 240 million years to circle the center of the galaxy.to circle the center of the galaxy.

An astronomical unit is the average distance An astronomical unit is the average distance between Earth and the sun. An astronomical unit between Earth and the sun. An astronomical unit is about 150,000,000 kmis about 150,000,000 km

We live in a spiral We live in a spiral galaxy called the galaxy called the Milky Way GalaxyMilky Way Galaxy

Our solar system lies Our solar system lies on one of the outer on one of the outer arms called Orions arms called Orions ArmArm


Where in the Milky Way Galaxy is Where in the Milky Way Galaxy is the solar system found?the solar system found?

A. In its centerA. In its center

B. In an inner armB. In an inner arm

C. In an outer armC. In an outer arm

D. Outside the Milky Way’s out edgeD. Outside the Milky Way’s out edge


A light year is a unit ofA light year is a unit of

A. time.A. time.

B. volume.B. volume.

C. speed.C. speed.

D. distance.D. distance.


If a space probe were able to move If a space probe were able to move at half the speed of light, how long at half the speed of light, how long would it take the probe to travel would it take the probe to travel from Earth to the center of the Milky from Earth to the center of the Milky Way Galaxy?Way Galaxy?

A. 15,000 light yearsA. 15,000 light years

B. 30,000 light yearsB. 30,000 light years

C. 60,000 light yearsC. 60,000 light years

D. 120,000 light yearsD. 120,000 light years


Light travels about 300,000 km a Light travels about 300,000 km a second. The sun is about second. The sun is about 150,000,000 km from Earth. About 150,000,000 km from Earth. About how long does light take to travel how long does light take to travel from the sun to Earth?from the sun to Earth?

A. 8 secondsA. 8 seconds B. 8 minutesB. 8 minutes C. 8 hoursC. 8 hours D. 8 yearsD. 8 years


The nearest star outside our solar The nearest star outside our solar system is about 4.2 light years away. system is about 4.2 light years away. About what distance would this be in About what distance would this be in kilometers?kilometers?

A. 40 trillionA. 40 trillion

B. 400 trillionB. 400 trillion

C. 4000 trillionC. 4000 trillion

D. 4 trillionD. 4 trillion

The Planets The Planets TermsTerms

MercuryMercury VenusVenus EarthEarth MarsMars

Pluto Pluto (Dwarf (Dwarf Planet)Planet)

JupiterJupiter SaturnSaturn UranusUranus NeptuneNeptune

How are the planets alike and/or How are the planets alike and/or different?different?

What factors exists on Earth What factors exists on Earth that make life possible here, that make life possible here, but unlikely on any other but unlikely on any other planet?planet?

Which planets in the solar Which planets in the solar system are called the “gas system are called the “gas giants” and why?giants” and why?

In general, what condition In general, what condition on the planets is MOST on the planets is MOST affected by its distance from affected by its distance from the sun?the sun?

The PlanetsThe Planets Earth’s atmosphere is about 78% nitrogen, 21% Earth’s atmosphere is about 78% nitrogen, 21%

oxygen.oxygen.

Liquid water, moderate temperature, and an Liquid water, moderate temperature, and an atmosphere rich in oxygen make Earth the only planet atmosphere rich in oxygen make Earth the only planet that can support life as we know it.that can support life as we know it.

The planets, Jupiter, Saturn, Uranus, and Neptune, are The planets, Jupiter, Saturn, Uranus, and Neptune, are called the “gas giants.” This is because they are so called the “gas giants.” This is because they are so much larger than Earth and they do not have well much larger than Earth and they do not have well defined surfaces.defined surfaces.

The condition on the planets that is most affected by The condition on the planets that is most affected by its distance from the sun is the temperature. The its distance from the sun is the temperature. The farther away they are from the sun, the lower the farther away they are from the sun, the lower the temperature on the planet.temperature on the planet.

The Inner Planets The Inner Planets MercuryMercury = = closest planet to the sun, only Pluto closest planet to the sun, only Pluto

is smaller, rocky surface with many craters, very is smaller, rocky surface with many craters, very thin atmosphere, high temperature, no life;thin atmosphere, high temperature, no life;

VenusVenus = = 22ndnd planet from sun, same size as Earth, planet from sun, same size as Earth, rocky surface, atmosphere is very thick with rocky surface, atmosphere is very thick with carbon dioxide, gas traps heat under it, no life;carbon dioxide, gas traps heat under it, no life;

EarthEarth = = 33rdrd planet from sun, surface is rocky, planet from sun, surface is rocky, covered with plains, valleys, mountains, plateaus, covered with plains, valleys, mountains, plateaus, active volcanoes, ¾ surface covered with water, active volcanoes, ¾ surface covered with water, atmosphere 78% nitrogen, 21% oxygen, water, atmosphere 78% nitrogen, 21% oxygen, water, moderate temperature, and oxygen makes Earth moderate temperature, and oxygen makes Earth only planet supporting life;only planet supporting life;

The Inner PlanetsThe Inner Planets

MarsMars = = 4th planet from the sun, called “red 4th planet from the sun, called “red planet”, half the size of Earth, rocky and dusty planet”, half the size of Earth, rocky and dusty surface, hills, plains, mountains, extinct surface, hills, plains, mountains, extinct volcanoes, craters, largest volcano in solar volcanoes, craters, largest volcano in solar system, ice caps north and south poles, may have system, ice caps north and south poles, may have had water at one time, thin atmosphere with had water at one time, thin atmosphere with carbon dioxide, life may have existed at one time;carbon dioxide, life may have existed at one time;

The Outer Planets The Outer Planets “Gas Giants”“Gas Giants”

JupiterJupiter = 5th planet from sun, largest planet, “gas = 5th planet from sun, largest planet, “gas giants," no solid surface, slushy ball of liquid giants," no solid surface, slushy ball of liquid hydrogen, atmosphere mostly helium and hydrogen hydrogen, atmosphere mostly helium and hydrogen gases, large red spot ( gigantic storm or hurricane), gases, large red spot ( gigantic storm or hurricane), circled by very thin rings, no life;circled by very thin rings, no life;

SaturnSaturn = 6th planet from sun, complex ring system, = 6th planet from sun, complex ring system, second largest planet, structure similar to Jupiter, second largest planet, structure similar to Jupiter, atmosphere is hydrogen and helium gases, no life;atmosphere is hydrogen and helium gases, no life;

UranusUranus = blue-green color from poisonous = blue-green color from poisonous methane, 7th planet from sun, third largest planet, methane, 7th planet from sun, third largest planet, surface completely covered with water, methane, and surface completely covered with water, methane, and ammonia, 11 rings circle planet, rotates on its side, ammonia, 11 rings circle planet, rotates on its side, poles point toward and away from sun, extremely poles point toward and away from sun, extremely cold temperature, no life; cold temperature, no life;

The Outer PlanetsThe Outer Planets“Gas Giants”“Gas Giants”

NeptuneNeptune = 8th planet from the sun, fourth = 8th planet from the sun, fourth largest planet, glows blue-green with methane largest planet, glows blue-green with methane gas clouds, icy ocean of water, methane, gas clouds, icy ocean of water, methane, ammonia, and hydrogen, six rings orbit planet, no ammonia, and hydrogen, six rings orbit planet, no life on planet;life on planet;

PlutoPluto = dwarf planet (?), smallest planet, = dwarf planet (?), smallest planet, smaller than Earth’s moon, may have rocky smaller than Earth’s moon, may have rocky surface, surface buried under layer of methane surface, surface buried under layer of methane ice, thin atmosphere of methane, nitrogen, and ice, thin atmosphere of methane, nitrogen, and carbon monoxide, too harsh to support life;carbon monoxide, too harsh to support life;

Is Pluto a planet? How does it compare and Is Pluto a planet? How does it compare and contrast with inner, outer planets?contrast with inner, outer planets?


What three factors exist on Earth that make What three factors exist on Earth that make life possible here, but unlikely on any other life possible here, but unlikely on any other planet?planet?

A. liquid water, moderate temperatures, atmospheric A. liquid water, moderate temperatures, atmospheric oxygenoxygen

B. liquid water, moderate temperatures, atmospheric B. liquid water, moderate temperatures, atmospheric nitrogennitrogen

C. liquid waters, moderate size of Earth, atmospheric C. liquid waters, moderate size of Earth, atmospheric oxygenoxygen

D. solid water, moderate temperatures, atmospheric D. solid water, moderate temperatures, atmospheric oxygenoxygen


Which planets in the solar Which planets in the solar system are called the “gas system are called the “gas giants”?giants”?

A. Mercury, Venus, Earth, MarsA. Mercury, Venus, Earth, Mars

B. Saturn, Uranus, Neptune, PlutoB. Saturn, Uranus, Neptune, Pluto

C. Jupiter, Saturn, Uranus, NeptuneC. Jupiter, Saturn, Uranus, Neptune

D. Earth, Venus, Pluto, MarsD. Earth, Venus, Pluto, Mars


Which planet is MOST LIKELY to Which planet is MOST LIKELY to support life as we know it?support life as we know it?

A. MercuryA. Mercury

B. VenusB. Venus

C. JupiterC. Jupiter

D. MarsD. Mars


In general, what condition is MOST In general, what condition is MOST affected by its distance from the sun?affected by its distance from the sun?

A. sizeA. size

B. temperatureB. temperature

C. atmosphereC. atmosphere

D. surface compositionD. surface composition


The force of gravity on a planet determines The force of gravity on a planet determines the weight of objects on the planet. If you the weight of objects on the planet. If you weighted 30 kg (66 pounds) on Earth, what weighted 30 kg (66 pounds) on Earth, what would you weigh on Jupiter?would you weigh on Jupiter?

A. 11.4 kg (5.2 pounds)A. 11.4 kg (5.2 pounds)

B. 30 kg (66 pounds)B. 30 kg (66 pounds)

C. 34.2 kg (75.4 pounds)C. 34.2 kg (75.4 pounds)

D. 75.9 kg (167.3 pounds)D. 75.9 kg (167.3 pounds)


Your spaceship is lost in the solar system. You arrive at Your spaceship is lost in the solar system. You arrive at a planet and begin orbiting it. Your instruments collect a planet and begin orbiting it. Your instruments collect the data shown in the table. What planet is below you?the data shown in the table. What planet is below you?

A. EarthA. Earth B. MarsB. Mars

C. JupiterC. Jupiter D. PlutoD. Pluto

Planet Average Distance from the Sun (x millions km)

Diameter(x 1000 km)

Year Length (on Earth days/years)

Gravity (x Earth’s )

Moons

Unknown 778 143.0 11.9 y 2.53 63


From nearest to farthest from the From nearest to farthest from the sun, which sequence is correct?sun, which sequence is correct?

A. Mercury, Venus, EarthA. Mercury, Venus, Earth

B. Mercury, Earth, VenusB. Mercury, Earth, Venus

C. Venus, Mercury, EarthC. Venus, Mercury, Earth

D. Venus, Earth, MercuryD. Venus, Earth, Mercury


Which of the following planets have a Which of the following planets have a rocky surface?rocky surface?

A. JupiterA. Jupiter

B. UranusB. Uranus

C. NeptuneC. Neptune

D. MercuryD. Mercury


In order from smallest to largest, In order from smallest to largest, which set of planets is correctly which set of planets is correctly shown?shown?

A. Mars, Earth, SaturnA. Mars, Earth, Saturn

B. Earth, Mars, SaturnB. Earth, Mars, Saturn

C. Saturn, Earth, MarsC. Saturn, Earth, Mars

D. Saturn, Mars, EarthD. Saturn, Mars, Earth


Mercury has a rocky surface and a very. Very Mercury has a rocky surface and a very. Very thin atmosphere. There is no liquid water on thin atmosphere. There is no liquid water on the planet, Daytime temperatures rise to the planet, Daytime temperatures rise to about 430about 430°C (806°F). Based on these data, what is the °C (806°F). Based on these data, what is the MOST reasonable conclusion you can reach about MOST reasonable conclusion you can reach about Mercury?Mercury?

A. It is the farthest planet from the sun.A. It is the farthest planet from the sun.B. It can support life.B. It can support life.C. It cannot surprise lifeC. It cannot surprise lifeIt is very much like Earth.It is very much like Earth.

Objects’ Motion in the Sky TermsObjects’ Motion in the Sky Terms

RotationRotation AxisAxis

Day Day YearYear

ConstellationConstellation RevolutionRevolution

Why do the sun and moon seem to Why do the sun and moon seem to move each day?move each day?

What causes day and What causes day and night?night?

If Earth’s rotation If Earth’s rotation slowed, what do you slowed, what do you think would be most think would be most affected?affected?

Compare and contrast Compare and contrast rotation and rotation and revolution.revolution.

RotationRotation Earth’s Earth’s rotationrotation on its axis causes day and night. on its axis causes day and night.

RotationRotation means spinning. Earth’s spinning on its means spinning. Earth’s spinning on its axis is called its rotation. Earth makes one axis is called its rotation. Earth makes one complete spin about every 24 hours. One complete spin about every 24 hours. One complete spin is called a complete spin is called a dayday..

It takes 24 hrs for the Earth to make one It takes 24 hrs for the Earth to make one complete spin on its axiscomplete spin on its axis. If the earth’s rotation . If the earth’s rotation slowed, a day would be longer. slowed, a day would be longer.

Earth spins around its axis from west to east. Earth spins around its axis from west to east. This makes objects in the sky appear to be This makes objects in the sky appear to be moving from east to west. moving from east to west.

RevolutionRevolution In addition to rotating on its axis, Earth In addition to rotating on its axis, Earth

travels around the suntravels around the sun. The movement of . The movement of one object around another object is called one object around another object is called revolutionrevolution..

One complete revolution around the sun is One complete revolution around the sun is called a year. Earth’s path as it revolves called a year. Earth’s path as it revolves around the sun is called its around the sun is called its orbitorbit..

As it travels around the sun, Earth’s orbit As it travels around the sun, Earth’s orbit is not a circle, it is is not a circle, it is ellipticalelliptical, like a slightly , like a slightly flattened circle, or oval shape.flattened circle, or oval shape.


What motion makes objects in the What motion makes objects in the sky seem to rise in the east and set sky seem to rise in the east and set in the west each day?in the west each day?

A. revolution of EarthA. revolution of Earth

B. rotation of EarthB. rotation of Earth

C. revolution of the sunC. revolution of the sun

D. rotation of the sunD. rotation of the sun


What does one revolution of Earth What does one revolution of Earth equal?equal?

A. an hourA. an hour

B. a dayB. a day

C. a monthC. a month

D. a yearD. a year


Around what does Earth rotate?Around what does Earth rotate?

A. its axisA. its axis

B. the sunB. the sun

C. the starsC. the stars

D. constellationsD. constellations


What motion of Earth makes it seem as if What motion of Earth makes it seem as if the stars and constellations are in different the stars and constellations are in different positions at different times of the year?positions at different times of the year?

A. Earth’s rotationA. Earth’s rotationB. the rotation of the stars and B. the rotation of the stars and constellationsconstellationsC. the revolution of the stars and C. the revolution of the stars and constellationsconstellationsD. the revolution of EarthD. the revolution of Earth


If Earth’s rotation slowed, which of the If Earth’s rotation slowed, which of the following would happen?following would happen?

A. The stars would not seem to change A. The stars would not seem to change position.position.

B. The length of a day would increase.B. The length of a day would increase.

C. The length of a day would decrease.C. The length of a day would decrease.

D. The length of a day would still be about D. The length of a day would still be about 24 hours.24 hours.


Assume Earth’s Assume Earth’s revolution increasedrevolution increased and and its its rotation decreasedrotation decreased. Which set of data . Which set of data would go with these changes?would go with these changes?

A. length of a year, 340 days; length of a day, A. length of a year, 340 days; length of a day, 26 26 hourshours

B. length of a year, 370 days; length of a day,B. length of a year, 370 days; length of a day, 28 hours28 hours

C. length of a year, 380 days; length of a day, C. length of a year, 380 days; length of a day, 23 23 hourshours

D. length of a year, 330 days; length of a day, D. length of a year, 330 days; length of a day, 20 20 hourshours


If the time it took Earth to If the time it took Earth to rotaterotate once on its axis once on its axis increasedincreased,,

A. a day would be longer.A. a day would be longer.

B. a day would be shorter.B. a day would be shorter.

C. a year would be longer.C. a year would be longer.

D. a year would be shorter.D. a year would be shorter.

Gravity TermsGravity Terms

GravityGravity InertiaInertia

OrbitsOrbits EllipseEllipse

How do the planets remain in How do the planets remain in their orbits their orbits ? ?

What two factors keep What two factors keep the planets in their the planets in their orbits?orbits?

What is gravity?What is gravity?

What is inertia?What is inertia?

What two factors does What two factors does the strength of the pull the strength of the pull of gravity depend of gravity depend upon?upon?

GravityGravity

All objects, from the atom to the largest All objects, from the atom to the largest family of stars, possess gravity.family of stars, possess gravity.

Gravity is a force that attracts all objects Gravity is a force that attracts all objects towards each other.towards each other.

The strength of the pull of gravity between The strength of the pull of gravity between two objects depends on two factors.two objects depends on two factors.

These two factors are the product of the These two factors are the product of the masses of the objects and the distance masses of the objects and the distance between them. between them.

GravityGravity As the product of the masses increases, the pull of As the product of the masses increases, the pull of

gravity also increases.gravity also increases.

If the distance between the two objects increases, If the distance between the two objects increases, then the pull of gravity between them decreases.then the pull of gravity between them decreases.

All objects in our solar system travel around the All objects in our solar system travel around the sun in paths called orbits.sun in paths called orbits.

Planets orbit around the sun, and moons are in Planets orbit around the sun, and moons are in orbit around planets.orbit around planets.

GravityGravity

Scientist Sir Isaac Newton discovered 3 Scientist Sir Isaac Newton discovered 3 Laws of Motion.Laws of Motion.

His 1st Law of Motion states that an object His 1st Law of Motion states that an object in motion will tend to stay in motion at the in motion will tend to stay in motion at the same speed and direction unless acted on same speed and direction unless acted on by an outside force.by an outside force.

The tendency of objects to keep doing The tendency of objects to keep doing what they were doing is called inertia.what they were doing is called inertia.

GravityGravity Inertia tends to lead planets to follow a Inertia tends to lead planets to follow a

straight path at a certain speed unless straight path at a certain speed unless acted on by an outside force. This outside acted on by an outside force. This outside force is the gravity of the sun.force is the gravity of the sun.

While the gravity of the sun pulls the While the gravity of the sun pulls the planet towards it, the speed and direction planet towards it, the speed and direction (inertia) of the planet pushes it forward.(inertia) of the planet pushes it forward.

When the forces of gravity and inertia are When the forces of gravity and inertia are balanced, the planet follows a curved path balanced, the planet follows a curved path around the sun.around the sun.

Quick CheckQuick CheckWhat force keeps Earth in orbit What force keeps Earth in orbit around the sun?around the sun?

A. a pull by one object that is in A. a pull by one object that is in contact with another object.contact with another object.

B. a push by one object that is in B. a push by one object that is in contact with another object.contact with another object.

C. massC. mass

D. gravityD. gravity


What affects the force of gravity What affects the force of gravity between two objects?between two objects?

A. the product of their masses and A. the product of their masses and the distance between themthe distance between them

B. only the distance between themB. only the distance between them

C. only the sum of their massesC. only the sum of their masses

D. the mass of the larger objectD. the mass of the larger object


In what direction does an object in In what direction does an object in space tend to move?space tend to move?

A. in a curved pathA. in a curved path

B. inwardB. inward

C. in a straight lineC. in a straight line

D. backwardD. backward

Quick CheckQuick CheckHow would the force of gravity How would the force of gravity between Earth and the sun be between Earth and the sun be affected if the mass of Earth were affected if the mass of Earth were greater than it is?greater than it is?

A. The force of gravity would be A. The force of gravity would be unchanged.unchanged.B. The force of gravity would be B. The force of gravity would be greater.greater.C. The force of gravity would be less.C. The force of gravity would be less.D. There would be no force of gravity.D. There would be no force of gravity.


If the force of gravity between Earth If the force of gravity between Earth and the sun were greater than and the sun were greater than Earth’s inertia, what would happen to Earth’s inertia, what would happen to Earth?Earth?

A. Earth would escape into space.A. Earth would escape into space.B. Earth would fall into the sun.B. Earth would fall into the sun.C. Earth would remain in its orbit C. Earth would remain in its orbit around the sun.around the sun.D. Earth would stop moving.D. Earth would stop moving.

How would you describe the How would you describe the characteristics of comets, asteroids, characteristics of comets, asteroids,

and meteoroids?and meteoroids? What is a comet What is a comet

made of?made of?

Where are most Where are most asteroids found?asteroids found?

What is the sequence What is the sequence that describes a that describes a meteoroid that falls meteoroid that falls to Earth’s surface?to Earth’s surface?

CometsComets

A comet is a chunk of material (ice and A comet is a chunk of material (ice and dust) called a nucleus.dust) called a nucleus.

When a comet gets close enough to the When a comet gets close enough to the sun, the energy in the sunlight turns the sun, the energy in the sunlight turns the ice into gas, releasing dust.ice into gas, releasing dust.

The gas and dust form an outer layer to The gas and dust form an outer layer to become an atmosphere called a coma.become an atmosphere called a coma.

CometsComets

Most comets revolve around the sun in Most comets revolve around the sun in very long, narrow orbits.very long, narrow orbits.

The main parts of a comet are the The main parts of a comet are the nucleus, the coma, and the tail.nucleus, the coma, and the tail.

As a comet gets closer to the sun, the As a comet gets closer to the sun, the sun’s energy blows parts of the comet sun’s energy blows parts of the comet away from the nucleus.away from the nucleus.

A comet’s tail always points away from A comet’s tail always points away from the sunthe sun because it is formed by energy of because it is formed by energy of the sun that blows outward from the sun.the sun that blows outward from the sun.

AsteroidsAsteroids Asteroids are chunks of rock and metal.Asteroids are chunks of rock and metal.

Most asteroids exist in a belt between the Most asteroids exist in a belt between the orbits of Mars and Jupiteorbits of Mars and Jupiterr. It is known as the . It is known as the asteroid belt.asteroid belt.

Some asteroids come near the orbit of Earth.Some asteroids come near the orbit of Earth.

65 million years ago, a large asteroid hit 65 million years ago, a large asteroid hit Earth making a large crater.Earth making a large crater.

Many scientist hypothesize that as a result Many scientist hypothesize that as a result many species of organisms, including many species of organisms, including dinosaurs, became extinct. dinosaurs, became extinct.

MeteoroidsMeteoroids

A A meteoroidmeteoroid is made up of chunks of rock is made up of chunks of rock or dust. Many come from comets and or dust. Many come from comets and asteroids.asteroids.

When a When a meteoroid enters Earth’s meteoroid enters Earth’s atmosphereatmosphere, it heats up and produces a , it heats up and produces a streak of light, streak of light, called a called a meteormeteor, or a , or a “shooting star.” “shooting star.”

Sometimes, a Sometimes, a meteoroidmeteoroid does not burn up does not burn up in Earth’s atmosphere and in Earth’s atmosphere and hits Earth’s hits Earth’s surfacesurface. Meteoroids that hit Earth’s . Meteoroids that hit Earth’s surface are surface are called called meteorites. meteorites.


When it approaches the sun, which When it approaches the sun, which object produces a shimmering tail object produces a shimmering tail that lasts at least a few days?that lasts at least a few days?

A. a meteoroidA. a meteoroid

B. an asteroidB. an asteroid

C. a cometC. a comet

D. the moonD. the moon


What is a comet’s coma?What is a comet’s coma?

A. the stony and icy center of its A. the stony and icy center of its headhead

B. a chunk of ironB. a chunk of iron C a stream of gases at its backC a stream of gases at its back D. the atmosphere around its D. the atmosphere around its

nucleusnucleus


Where are MOST asteroids found?Where are MOST asteroids found?

A. all over the solar systemA. all over the solar system

B. outside the solar systemB. outside the solar system

C. in orbit between Mars and JupiterC. in orbit between Mars and Jupiter

D. near EarthD. near Earth


What is the sequence that describes What is the sequence that describes a space rock that falls to Earth’s a space rock that falls to Earth’s surface?surface?

A. meteoroid, meteor, meteoriteA. meteoroid, meteor, meteorite

B. meteorite, meteor, meteoroidB. meteorite, meteor, meteoroid

C. meteor, meteoroid, meteoriteC. meteor, meteoroid, meteorite

D. meteoroid, meteorite, meteorD. meteoroid, meteorite, meteor


Meteoroids usually come fromMeteoroids usually come from

A. debris from other planetsA. debris from other planets

B. the moonB. the moon

C. beyond the solar systemC. beyond the solar system

D. comets or asteroidsD. comets or asteroids

The Phases of the Moon TermsThe Phases of the Moon Terms

PhasesPhases = one of the different = one of the different shapes of the moon as seen from shapes of the moon as seen from EarthEarth

Waxing = bright part of the moon Waxing = bright part of the moon increaseincrease in size in size as time passesas time passes

Waning = bright part of the moon Waning = bright part of the moon decreasesdecreases in size in size as time passes.as time passes.

How does the moon change How does the moon change phases?phases?

What causes the What causes the phases of the phases of the moon?moon?

What are the 8 What are the 8 names of the names of the phases of the phases of the moon?moon?

Since the moon Since the moon does not produce does not produce light, how can you light, how can you see it?see it?

The Phases of the MoonThe Phases of the Moon The changing shapes of the moon we see are The changing shapes of the moon we see are

called phases. The phase of the moon you see called phases. The phase of the moon you see depends on how much of the sunlit side of the depends on how much of the sunlit side of the moon faces Earth.moon faces Earth.

The moon shows all of its phases in a cycle that The moon shows all of its phases in a cycle that lasts 29.5 days.lasts 29.5 days.

The names of the moon’s 8 phases in order of The names of the moon’s 8 phases in order of appearance are: new moon, waxing crescent, first appearance are: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning quarter, waxing gibbous, full moon, waning gibbous, 3gibbous, 3rdrd (last) quarter, waning crescent. (last) quarter, waning crescent.

Since the moon does not produce light, light from Since the moon does not produce light, light from the sun reflects off the moon, enabling it to be the sun reflects off the moon, enabling it to be seen from Earth.seen from Earth.

The Phases of the MoonThe Phases of the Moon

Waxing means “increasing.”Waxing means “increasing.” Waning means “decreasing.”Waning means “decreasing.” The moon does not produce its own The moon does not produce its own

light. It reflects sunlight in all light. It reflects sunlight in all directions.directions.

During a During a new moonnew moon, the moon is , the moon is between the sun and Earth, you between the sun and Earth, you cannot see the moon.cannot see the moon.

The Phases of the MoonThe Phases of the Moon

After a few days, as the moon orbits Earth, After a few days, as the moon orbits Earth, , it is no longer between the sun and , it is no longer between the sun and Earth. Earth.

A little part of the moon’s face reflects A little part of the moon’s face reflects sunlight toward Earth= waxing sunlight toward Earth= waxing (increasing) crescent.(increasing) crescent.

When When half half of the moon’s bright side faces of the moon’s bright side faces Earth, it is a Earth, it is a first quarter moon.first quarter moon.

During a During a waxing gibbouswaxing gibbous, most of the , most of the moon’s lighted side faces Earth.moon’s lighted side faces Earth.

The Phases of the MoonThe Phases of the Moon When the moon is half way through its When the moon is half way through its

cycle, the side that faces Earth is opposite cycle, the side that faces Earth is opposite of the sun. of the sun. Earth sees all of the moon’s Earth sees all of the moon’s bright face. This is called a bright face. This is called a full moonfull moon..

As the cycle continues, we see less and As the cycle continues, we see less and less of the bright side of the moon. less of the bright side of the moon.

In decreasing order, In decreasing order, waning gibbous, waning gibbous, third quarter moon, waning crescent.third quarter moon, waning crescent.

After After 29.5 days29.5 days, the cycle is complete. , the cycle is complete. Another Another new moonnew moon has appeared. has appeared.


The position of what objects is The position of what objects is responsible for the moon’s phases?responsible for the moon’s phases?

A. only EarthA. only Earth

B. only the moon and EarthB. only the moon and Earth

C. only the moon and the sunC. only the moon and the sun

D. the moon, Earth, and the sunD. the moon, Earth, and the sun


About how long does it take the About how long does it take the moon to complete one cycle of moon to complete one cycle of phases?phases?

A. one dayA. one day

B. one weekB. one week

C. one monthC. one month

D. one yearD. one year


Which is the correct order of the moon’s Which is the correct order of the moon’s phases?phases?

A. waxing crescent, waning crescent, first A. waxing crescent, waning crescent, first quarterquarter

B. waning gibbous, last quarter, waxing B. waning gibbous, last quarter, waxing gibbousgibbous

C. full moon, new moon, first quarterC. full moon, new moon, first quarterD. waxing gibbous, full moon, waning D. waxing gibbous, full moon, waning

gibbousgibbous


How much of the moon’s surface can How much of the moon’s surface can you see during a new moon phase?you see during a new moon phase?

A. noneA. none

B. one-quarterB. one-quarter

C. one halfC. one half

D. all of itD. all of it

Quick checkQuick check

What phase of the moon would you What phase of the moon would you see about three weeks after a new see about three weeks after a new moon?moon?

A. full moonA. full moon

B. waning gibbousB. waning gibbous

C. last quarterC. last quarter

D. the next new moonD. the next new moon

Quick Check AnswerQuick Check Answer

What phase of the moon would you What phase of the moon would you see about three weeks after a new see about three weeks after a new moon?moon?

C. last quarterC. last quarter

Solar and Lunar Eclipse TermsSolar and Lunar Eclipse Terms

Lunar eclipseLunar eclipse solar eclipsesolar eclipse

Total eclipseTotal eclipse partial partial eclipseeclipse

How does Earth, the moon, and the How does Earth, the moon, and the sun align during a solar eclipse and sun align during a solar eclipse and

lunar eclipse?lunar eclipse? What causes solar and What causes solar and

lunar eclipses?lunar eclipses?

Why do lunar eclipses Why do lunar eclipses occur only at full occur only at full moon?moon?

Describe the relative Describe the relative positions of Earth, the positions of Earth, the sun, and the moon sun, and the moon during a solar eclipse during a solar eclipse and during a lunar and during a lunar eclipse.eclipse.

Solar and Lunar EclipsesSolar and Lunar Eclipses A solar and lunar eclipse occurs only A solar and lunar eclipse occurs only

when the earth, moon, and sun are when the earth, moon, and sun are directly lined up.directly lined up.

There are two types of eclipses.There are two types of eclipses. The moon goes dark during a lunar The moon goes dark during a lunar

eclipse.eclipse. The sun goes dark during a solar eclipse.The sun goes dark during a solar eclipse. A lunar eclipse occurs when Earth passes A lunar eclipse occurs when Earth passes

directly between the sun and the moon. directly between the sun and the moon. The Earth casts a shadow on the moon.The Earth casts a shadow on the moon.

Lunar and Solar EclipsesLunar and Solar Eclipses A lunar eclipse can happen only during full moon. A lunar eclipse can happen only during full moon.

This is because it is the only time when Earth, the This is because it is the only time when Earth, the sun, and the moon are directly lined up with the sun, and the moon are directly lined up with the Earth between the moon and the sun.Earth between the moon and the sun.

A solar eclipse occurs when the moon passes A solar eclipse occurs when the moon passes directly between the sun and Earth. The moon directly between the sun and Earth. The moon casts a shadow on a part of Earth’s surface.casts a shadow on a part of Earth’s surface.

A solar eclipse can happen only during a new A solar eclipse can happen only during a new moon. This is because it is the only time when moon. This is because it is the only time when Earth, the sun, and the moon are directly lined up Earth, the sun, and the moon are directly lined up with the moon between Earth and the sun.with the moon between Earth and the sun.

Solar and Lunar EclipsesSolar and Lunar Eclipses There is not a lunar or solar eclipse every There is not a lunar or solar eclipse every

month because the moon is not always on month because the moon is not always on the same plane as Earth and the sun. the same plane as Earth and the sun.

The moon orbits Earth at an angle.The moon orbits Earth at an angle. An eclipse can be total or partial. An eclipse can be total or partial.

A total eclipse occurs when the moon or A total eclipse occurs when the moon or sun becomes completely covered.sun becomes completely covered.

A partial eclipse occurs when the moon or A partial eclipse occurs when the moon or sun becomes only partly covered.sun becomes only partly covered.


Under what conditions will an eclipse take Under what conditions will an eclipse take place?place?

A. only when the sun and Earth are A. only when the sun and Earth are directly lined updirectly lined upB. only when the moon and Earth are B. only when the moon and Earth are directly lined updirectly lined upC. only when the moon, the sun, and C. only when the moon, the sun, and Earth are not exactly lined upEarth are not exactly lined upD. only when the moon, the sun, and D. only when the moon, the sun, and Earth are directly lined upEarth are directly lined up


What phase must the moon be in to What phase must the moon be in to allow for a lunar eclipse?allow for a lunar eclipse?

A. newA. new

B. fullB. full

C. first quarterC. first quarter

D. waxing gibbousD. waxing gibbous


Although the moon is much smaller than the sun, Although the moon is much smaller than the sun, it looks about the same size when viewed from it looks about the same size when viewed from Earth. What fact might account for this Earth. What fact might account for this observation?observation?

A. The moon is farther from Earth than A. The moon is farther from Earth than the sun.the sun.B. Earth is closer to the sun than the B. Earth is closer to the sun than the moonmoonC. The moon is closer to Earth than the C. The moon is closer to Earth than the sun.sun.D. The moon shines brighter than the sun.D. The moon shines brighter than the sun.


What conditions would produce a partial What conditions would produce a partial eclipse of the moon?eclipse of the moon?

A. the moon is on the same plane as the A. the moon is on the same plane as the sun and Earthsun and Earth

B. the moon is below the plane of the sun B. the moon is below the plane of the sun and Earthand Earth

C. the moon is far above the plane of the C. the moon is far above the plane of the sun and Earthsun and Earth

D. none of the aboveD. none of the above


When Earth’s shadow falls on the When Earth’s shadow falls on the moon, the shadow causes amoon, the shadow causes a

A. new moon.A. new moon.

B. solar eclipse.B. solar eclipse.

C. full moon.C. full moon.

D. lunar eclipse.D. lunar eclipse.

The Tilt of Earth TermsThe Tilt of Earth Terms

Earth’s tiltEarth’s tilt 23.5°23.5°

summer solsticesummer solstice autumnal autumnal equinoxequinox• (June 21st)(June 21st) (Sept. 22nd)(Sept. 22nd)

winter solsticewinter solstice vernal equinoxvernal equinox• (Dec. 21st)(Dec. 21st) (March 21st)(March 21st)

Why does Earth have a cycle of Why does Earth have a cycle of seasons?seasons?

What two factors What two factors cause the cycle of cause the cycle of seasons?seasons?

How is Earth’s axis How is Earth’s axis tilted when the tilted when the Northern Hemisphere Northern Hemisphere has summer?has summer?

What does the word What does the word equinox mean? How is equinox mean? How is it related to the it related to the position of Earth’s position of Earth’s axis?axis?

The Tilt of EarthThe Tilt of Earth Earth’s axis is tilted from its orbit around the Earth’s axis is tilted from its orbit around the

sun by 23.5°.sun by 23.5°.

Earth has seasons because its axis is tilted as Earth has seasons because its axis is tilted as it moves around the sun.it moves around the sun.

As Earth revolves around the sun, its axis is As Earth revolves around the sun, its axis is tilted away from the sun part of the year and tilted away from the sun part of the year and toward the sun for part of the year.toward the sun for part of the year.

The cycle of seasons is caused by Earth’s The cycle of seasons is caused by Earth’s revolution around the sun and the tilt of revolution around the sun and the tilt of Earth’s axis.Earth’s axis.

The Tilt of EarthThe Tilt of Earth Summer solsticeSummer solstice (June 21)is the first day (June 21)is the first day

of summer in the Northern Hemisphere. At of summer in the Northern Hemisphere. At this time, Earth’s North Pole is tilted a full this time, Earth’s North Pole is tilted a full 23.5° toward the sun. This Hemisphere of 23.5° toward the sun. This Hemisphere of Earth has its longest day.Earth has its longest day.

Autumnal equinox Autumnal equinox (Sept. 22) signals the (Sept. 22) signals the first day of autumn. At this point, Earth is first day of autumn. At this point, Earth is neither pointed toward or away from the neither pointed toward or away from the sun. sun.

All parts of Earth have days and nights that All parts of Earth have days and nights that are almost equal in length.are almost equal in length.

The Tilt of EarthThe Tilt of Earth Winter solstice Winter solstice (Dec. 21) is the first day (Dec. 21) is the first day

of winter in the Northern Hemisphere and of winter in the Northern Hemisphere and is a point in Earth’s orbit. Earth’s North is a point in Earth’s orbit. Earth’s North Pole is tilted a full 23.5° away from the Pole is tilted a full 23.5° away from the sun.sun.

Sunlight strikes areas north of the Sunlight strikes areas north of the equator at a greater angle than at any equator at a greater angle than at any other time of the year.other time of the year.

Days are the shortest and nights are the Days are the shortest and nights are the longest.longest.

The Tilt of EarthThe Tilt of Earth

Vernal equinoxVernal equinox (March 20) marks (March 20) marks the first day of spring in the Northern the first day of spring in the Northern Hemisphere.Hemisphere.

At this time, Earth is not tilted toward At this time, Earth is not tilted toward or away from the sun.or away from the sun.

Days and nights are of equal length.Days and nights are of equal length.

Seasons on EarthSeasons on Earth At the equator, sunlight hits Earth’s surface more At the equator, sunlight hits Earth’s surface more

directly or at smaller angles.directly or at smaller angles.

Closer to the poles, sunlight hits Earth’s surface Closer to the poles, sunlight hits Earth’s surface at greater angles. Near the poles, energy from at greater angles. Near the poles, energy from the sun is spread out over a greater area.the sun is spread out over a greater area.

For this reason, areas near the equator have a For this reason, areas near the equator have a very warm climate, and areas farther from the very warm climate, and areas farther from the equator have cooler climates.equator have cooler climates.

Areas farthest from the equator have the coldest Areas farthest from the equator have the coldest climate since sunlight strikes these areas at the climate since sunlight strikes these areas at the greatest angle.greatest angle.


On the first day of which season, or On the first day of which season, or seasons, in the Northern Hemisphere seasons, in the Northern Hemisphere is Earth neither tilted toward or away is Earth neither tilted toward or away from the sun?from the sun?

A. winterA. winterB. spring and autumnB. spring and autumnC. only springC. only springD. summerD. summer


What is the season in the Southern What is the season in the Southern Hemisphere of Earth when it is Hemisphere of Earth when it is summer in the Northern summer in the Northern Hemisphere?Hemisphere?

A. springA. springB. autumnB. autumnC. winterC. winterD. summerD. summer


On which of the following dates is the On which of the following dates is the Northern Hemisphere of Earth tilted Northern Hemisphere of Earth tilted away from the sun at the greatest away from the sun at the greatest angle?angle?

A. March 20A. March 20B. June 21B. June 21C. September 22C. September 22D. December 21D. December 21


At what angle is Earth tilted on its At what angle is Earth tilted on its axis?axis?

A. 0°A. 0°

B. 23.5°B. 23.5°

C. 45°C. 45°

D. 90°D. 90°


About how many hours of daylight About how many hours of daylight would you expect people in Chicago would you expect people in Chicago to experience on February 1?to experience on February 1?

A. 10A. 10

B. 12B. 12

C. 14C. 14

D. 16D. 16

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Astronomy How is the geocentric theory different from the heliocentric theory?