table of contents the sky from earth earth in space gravity and motion phases and eclipses tides...
TRANSCRIPT
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