Table of Contents The Sky From Earth Earth in Space Gravity and Motion Phases and Eclipses Tides Earth’s Moon Earth, Moon, and Sun.

Table of Contents

The Sky From Earth

Earth in Space

Gravity and Motion

Phases and Eclipses

Tides

Earth’s Moon

Earth, Moon, and Sun

Chapter 6 Big Question

• How do earth, the moon, and the sun interact?

Chapter 6 Lesson 1: The Sky from Earth

• Objectives: • Identify objects and constellations visible in

the night sky without a telescope• Describe the apparent motion of stars and

planets throughout the year.

What Can You See in the Night Sky?• On a clear night we may see:

The moon Earth’s only natural SATELLITE (body that orbits a planet)

PLANETS Objects that orbit the sun Large enough to have become rounded by its own gravity Cleared the area of its orbit (no obstacles) Can see 5 without a telescope

Mercury, Venus, Mars, Jupiter, Saturn

METEORS Streak of light produced when a small object burns up

entering Earth’s atmosphere

What Can You See in the Night Sky?• On a clear night we may see:

COMETS Cold mixture of dust and ice Give a long trail of light as it approaches the sun More rare than meteors

STARS A giant ball of hot gas mainly composed of hydrogen and

helium

The Sky From Earth

CONSTELLATIONSA constellation is a pattern or group of stars that people imagined to represent a figure, animal, or object.

Finding ConstellationsWhat are the names of the constellations in this figure?

The Sky From Earth

How Do Objects in the Sky Appear to Move?

• Stars, planets, and other objects move in space• Their actual motions and their apparent motions

(how they look like they are moving) may be very different

• The apparent motion depends on the motions of the Earth

• Stars, the moon, and the sun appear to move from east to west across Earth’s sky. (apparent motion)

• Earth is actually turning from the west to east.• Earth rotation

Seasonal Changes

• Constellations vary from season to season depending on where earth is on its orbit around the sun.

• Each night the position of stars shifts slightly to the west.

• Planets all orbit the sun in about the same plane• They appear to move through the zodiac, a narrow

band in the sky

Opposite MotionsWhere would the mountain appear at each time shown?

The Sky From Earth

Chapter 6 Lesson 2: Earth in Space

• Objectives: • Demonstrate how Earth moves• Explain what causes the cycle of seasons on

Earth

The earth moves in space in two major ways: rotation and revolution.

How Does Earth Move?

Earth's RotationIn which direction does the Earth rotate?

Rotation

Rotation

• The spinning of the Earth along its AXIS is called its ROTATION. Causes day and night Each 24 hour ROTATION is called a day

Revolution

• The movement of one object around another• One revolution around the sun is one year• Our path, or ORBIT, around the sun is an

ellipse.• Brings the planet closest to the sun in January

Calendar

• Divides time based on the motions of the Earth and moon

• System of organizing time that defines the beginning, length, and divisions of the year

• Most commonly divided into:–-years (one revolution) –-months (based on the moon’s cycle ~ 29 days)–-days (one rotation)

What Causes Seasons?

• How Sunlight Hits Earth• near equator, sunlight hits almost overhead• Poles receive sunlight at a steep angle

•Earth’s Tilted Axis• Tilted 23.5 degrees from the vertical• Without the tilted axis, there would be no seasons

• North Pole will point away for part of the year, and toward the sun for the other part

Sunlight on EarthThe diagram shows how Earth’s tilted axis affects the strength of sunlight in different places.

Earth in Space

SeasonsThe diagram shows how Earth moves during the year.

Earth in Space

Solstices• Point of the year when the sun appears farthest north and south

of the equator • June 21st

• -Farthest north• -summer solstice in the Northern Hemisphere (longest day of the year)• -winter solstice in the Southern Hemisphere (shortest day of the year)• December 21st

• -Farthest south• -winter solstice in the Northern Hemisphere• -summer solstice in the Southern Hemisphere

Equinoxes

• Halfway in between solstices• Neither hemisphere is tilted toward the sun• Noon sun is directly over equator• “equal days, equal nights”-day and night are

about 12 hours each• March 21st

• Vernal Equinox (Spring) in Northern Hemisphere• September 22nd

• Autumnal (Fall) Equinox in Northern Hemisphere

Earth in Space

Solstices and EquinoxesThe diagrams show the apparent path of the sun at the solstices and equinoxes in the Northern Hemisphere. What is the sun’s path at the equinoxes and the December solstice for the Southern Hemisphere?

Calculating PercentsThe table shows the number of hours of sunlight in three cities at different times of year.

Earth in Space

Gravity and Motion

Gravity AssistsHow does a planet's gravity change the path of a space probe?

Gravity and Motion

Gravity AssistsHow does a planet's gravity change the path of a space probe?The planet’s gravity pulls the space probe into a new direction.

What Determines Gravity?

I. Gravity a. attracts all objects toward each otherb. Sir Isaac Newton is credited with this realizationc. Depends on two factors: masses of the objects and the

distance between themd. The greater the mass, the greater the forcee. Weight

– 1. Measure of force of gravity on an –object– 2. Can change depending on location– 3. Moon’s gravity is 1/6th of Earth’s– 4. Moon has less mass!

What Determines Gravity?

•f. Force of gravity between two objects decreases as the distance between the objects increases. (As objects get further away from each other, the gravity decreases)

Gravity and Motion

Orbital MotionHow would the moon move if Earth's mass increased?

What Keeps Objects in Orbit?

I. Inertia a. Newton’s first law of motion

1. An object in motion stays in motion 2. An object at rest stays at rest3. unless acted upon by an outside force

What Keeps Objects in Orbit?

I. Inertia a. Newton’s first law of motion

1. An object in motion stays in motion 2. An object at rest stays at rest3. unless acted upon by an outside force

b. The more mass an object has, the greater the inertia.c. The greater the inertia, the harder the object is to start or

stop.d. Inertia and gravity combine to:

1. keep Earth in orbit around the sun 2. Keep the moon in orbit around the Earth

Gravity Versus DistanceAs a rocket leaves a planet’s surface, the force of gravity between the rocket and the planet changes.

Gravity and Motion

Chapter 6 Lesson 4: Phases and Eclipses

•Objectives: –Explain what cases the phases of the moon–Describe solar and lunar eclipses

What Causes the Moon’s Phases?

• The motions of the moon around the earth• The relative positions of the moon, Earth, and

sun change, causing the phases of the moon.• Depends on how much of the sunlight side of

the moon faces Earth• 8 phases• One lunar cycle is 29.5 days

Phases and Eclipses

The Moon’s MotionWhere would the moon's face appear in each view in this diagram that shows the moon's rotation and revolution?

Phases and Eclipses

Moon PhasesAs the moon orbits Earth, its sunlit side is seen from different angles.

History Channel: Moon

What Are Eclipses?

• Solar Eclipse– New Moon– Moon passes directly between the Earth and the

sun

What Are Eclipses?

• Solar Eclipse– New Moon– Moon passes directly between the Earth and the

sun

Sun Moon Earthumbra

sunlight

sunlight

What Are Eclipses?

• Lunar Eclipse– Full Moon– Earth is directly between the moon and the sun– Earth blocks sunlight from reaching the moon

Sun

Moo

n Earth umbra

sunlight

sunlight

Solar EclipseThe diagram shows the moon’s penumbra and umbra during an eclipse.

Phases and Eclipses

Lunar EclipseAs the moon moves through Earth’s shadow, total and partial eclipses occur.

Phases and Eclipses

Seasons and ShadowsIdentify what season it is in the Northern Hemisphere, what the phase of the moon is, and what kind of eclipse, if any, could occur.

Phases and Eclipses

Tide CycleTides are caused mainly by differences in how much gravity from the moon and the sun pulls on different parts of Earth.

Tides

The Sun’s Role Changes in the positions of Earth, the moon, and the sun affect the heights of the tides during a month. What is the position of the moon and where are the tide bulges at third quarter?

Tides

High and Low TidesThe table shows high and low tides at four times in May 2008, in St. John, New Brunswick.

Tides

Earth’s Moon

Galileo GalileiGalileo invented the telescope in 1609 and used it to view the moon's surface.

Different WorldsCompare and contrast Earth and the moon.

Earth’s Moon

Going to the MoonWhat would you pack?

Earth’s Moon