Earth’s Rotation

& Revolution

Earth’s Rotation

& RevolutionChapter 2 , Section

1:1Chapter 2 , Section

1:1

Section ObjectivesSection Objectives

Identify what makes up the solar system.

Describe how Earth moves in space.

Describe how Earth’s tilt, rotation, and revolution around the sun cause the four seasons.

Identify what makes up the solar system.

Describe how Earth moves in space.

Describe how Earth’s tilt, rotation, and revolution around the sun cause the four seasons.

The Solar SystemThe Solar SystemOur solar system = 8 planets (including

Earth) and many smaller bodies, all orbiting the sun

Our solar system = 8 planets (including Earth) and many smaller bodies, all orbiting the sun

A Tour Through the Rest of the Solar System

A Tour Through the Rest of the Solar System

Mercury Venus Earth Mars

The Big Picture - Comparing Planet and Star Sizes (2:34)

Disqualified: Poor Little Pluto!

Disqualified: Poor Little Pluto!

FUN FACTS Discovered in 1930 Since then, many other similar

bodies have been found, including at least one asteroid - Eris - that is larger than Pluto

In 2006, astronomers classed Pluto and Eris as dwarf planets

Some astronomers believe that Pluto was once a moon of Neptune but it somehow escaped into its own orbit.

Technically, Pluto's name is now 134340 after being declassified as a planet.

Because of Pluto's irregular orbit, there are periods of times when it is closer to the sun than Neptune.

What Happened to Pluto? (3:31)

FUN FACTS Discovered in 1930 Since then, many other similar

bodies have been found, including at least one asteroid - Eris - that is larger than Pluto

In 2006, astronomers classed Pluto and Eris as dwarf planets

Some astronomers believe that Pluto was once a moon of Neptune but it somehow escaped into its own orbit.

Technically, Pluto's name is now 134340 after being declassified as a planet.

Because of Pluto's irregular orbit, there are periods of times when it is closer to the sun than Neptune.

What Happened to Pluto? (3:31)

Elliptical Orbits

Orbit: the path a planet or other object travels as it rotates around the solar system Orbits have an elliptical shape Each planet or object takes a different amount of time

to complete its orbitEarth: 1 orbit = 365 ¼ days (1 year)Mercury: 1 orbit = 88 days (abt 3 mos.)Pluto: 1 orbit = 250 years

Orbit: the path a planet or other object travels as it rotates around the solar system Orbits have an elliptical shape Each planet or object takes a different amount of time

to complete its orbitEarth: 1 orbit = 365 ¼ days (1 year)Mercury: 1 orbit = 88 days (abt 3 mos.)Pluto: 1 orbit = 250 years

Like EarthMercury, Venus, and Mars (also Pluto)Solid and smallFew or no moonsRotate or spin slowly

Like JupiterHuge balls of gasHave many moons and/or ringsSpin rapidly

Like EarthMercury, Venus, and Mars (also Pluto)Solid and smallFew or no moonsRotate or spin slowly

Like JupiterHuge balls of gasHave many moons and/or ringsSpin rapidly

Two Types of Planets

The SunThe SunAbout 93 million miles from EarthMade mostly of intensely hot

gases - as hot as 27 million degrees Fahrenheit!

Light and warmth from the Sun makes life on earth possible!

About 93 million miles from EarthMade mostly of intensely hot

gases - as hot as 27 million degrees Fahrenheit!

Light and warmth from the Sun makes life on earth possible!

The Sun, cont.

The Sun, cont.

Inside the Sun (6:13)Inside the Sun (6:13)

The EarthThe Earth

The MoonThe MoonEarth’s nearest neighborOrbits Earth every 30 daysCold and rocky, no water or

atmosphereGives off no light Light seen when the moon

“shines” is actually a reflection from the sun!

First Moonwalk, 1969 (1:44)

Earth’s nearest neighborOrbits Earth every 30 daysCold and rocky, no water or

atmosphereGives off no light Light seen when the moon

“shines” is actually a reflection from the sun!

First Moonwalk, 1969 (1:44)

EclipsesEclipses A solar eclipse occurs when the

moon moves between the sun and the earth, thus completely blocking out the sun for a part of the planet

A lunar eclipse is when the sun blocks the moon from sight on earth

Solar Eclipse: Turkey, 2008 (2:22)

A solar eclipse occurs when the moon moves between the sun and the earth, thus completely blocking out the sun for a part of the planet

A lunar eclipse is when the sun blocks the moon from sight on earth

Solar Eclipse: Turkey, 2008 (2:22)

Earth’s Movement

Earth’s Movement

Every planet rotates, or spins, on its axisAxis: an imaginary line the runs through Earth’s

center between the North and South Poles It takes 24 hours to finish a complete spin on Earth’s

axis24 hours = 1 dayAs Earth spins, different parts of the planet are in light

or darkness

Every planet rotates, or spins, on its axisAxis: an imaginary line the runs through Earth’s

center between the North and South Poles It takes 24 hours to finish a complete spin on Earth’s

axis24 hours = 1 dayAs Earth spins, different parts of the planet are in light

or darkness

Earth’s Movement (cont.)Earth’s Movement (cont.)Earth orbits the

Sun once every 365 ¼ days. 365 days = 1 yearEvery four years,

1 day is added (¼+¼+¼+¼=1) as Feb.29!This is called a

leap year!What is a Leap

Year? (3:58)

Earth orbits the Sun once every 365 ¼ days. 365 days = 1 yearEvery four years,

1 day is added (¼+¼+¼+¼=1) as Feb.29!This is called a

leap year!What is a Leap

Year? (3:58)

The Sun and the SeasonsThe Sun and the Seasons

Earth is tilted 23 ½° (degrees) on its axis

Seasons change as the Earth orbits orbits around the SunWhen the Northern or Southern

Hemispheres receive DIRECT RAYS from the Sun, they experience summer

When those hemispheres receive INDIRECT RAYS from the Sun, they experience winter

This is why hemispheres have opposite seasons Winter in the Northern Hemisphere = summer in the

Southern Hemisphere! Reasons for the Seasons (2:18)

Earth is tilted 23 ½° (degrees) on its axis

Seasons change as the Earth orbits orbits around the SunWhen the Northern or Southern

Hemispheres receive DIRECT RAYS from the Sun, they experience summer

When those hemispheres receive INDIRECT RAYS from the Sun, they experience winter

This is why hemispheres have opposite seasons Winter in the Northern Hemisphere = summer in the

Southern Hemisphere! Reasons for the Seasons (2:18)

The Sun and Seasons (cont.)

The Sun and Seasons (cont.)

Solstices and EquinoxesSolstices and EquinoxesFour days mark the beginning of the four

seasons: Solstices and Equinoxes (5:53)Summer Solstice (June 21)

North Pole is tilted toward the SunSun is directly over Tropic of Cancer (23 1/2˚ N)Northern Hemisphere - longest day, shortest night (opposite

in Southern Hemisphere)Winter Solstice (December 22)

North Pole is tilted away from the SunSun is directly over Tropic of Capricorn (23 1/2˚ S)Northern Hemisphere - shortest day, longest night (opposite

in Southern Hemisphere)Vernal (Spring) Equinox (around March 21) and

Autumnal (Fall) Equinox (around September 23)Day and night of equal lengthSun shines directly over the Equator

Four days mark the beginning of the four seasons: Solstices and Equinoxes (5:53)Summer Solstice (June 21)

North Pole is tilted toward the SunSun is directly over Tropic of Cancer (23 1/2˚ N)Northern Hemisphere - longest day, shortest night (opposite

in Southern Hemisphere)Winter Solstice (December 22)

North Pole is tilted away from the SunSun is directly over Tropic of Capricorn (23 1/2˚ S)Northern Hemisphere - shortest day, longest night (opposite

in Southern Hemisphere)Vernal (Spring) Equinox (around March 21) and

Autumnal (Fall) Equinox (around September 23)Day and night of equal lengthSun shines directly over the Equator

Any questions?Any questions?