The Earth, Moon, and Sun The Earth, Moon, and Sun SystemSystem

SOL 6.8SOL 6.8

IntroductionIntroduction

In this presentation we will learn:In this presentation we will learn: About the relative sizes, motions, locations, and About the relative sizes, motions, locations, and

characteristics of the earth, sun and moon. characteristics of the earth, sun and moon. Vocabulary includes: rotation, revolution, axis of rotation, orbital plane, Vocabulary includes: rotation, revolution, axis of rotation, orbital plane, periods of rotation and revolution, mass, diameter, radius of orbit, periods of rotation and revolution, mass, diameter, radius of orbit,

density, density, composition, surface, core, atmosphere.composition, surface, core, atmosphere.

The effects of their motions and positions on our The effects of their motions and positions on our seasons, tides, eclipses, and the measurement of seasons, tides, eclipses, and the measurement of time. time.

Vocabulary includes: seasons, high and low tides, phases of the Vocabulary includes: seasons, high and low tides, phases of the moon, moon, equinoxes, solstices, perihelion, aphelion, day, night, month, year, equinoxes, solstices, perihelion, aphelion, day, night, month, year, solar solar and lunar eclipses.and lunar eclipses.

Lets compare all three Lets compare all three

heavenly bodiesheavenly bodies

for a minute!!for a minute!!

We’ll start with the SunWe’ll start with the Sun

The SunThe Sun

A G2 typical yellow dwarf starA G2 typical yellow dwarf star

DiameterDiameter: 1.4 million kilometers: 1.4 million kilometers Contains 99.8% of the mass of Contains 99.8% of the mass of

the solar systemthe solar system

CompositionComposition: 75% hydrogen, : 75% hydrogen, 25% helium25% helium

Surface TemperatureSurface Temperature: 5500 : 5500 ooCC

Core TemperatureCore Temperature: 15 million : 15 million degrees Celsiusdegrees Celsius

Rotates on its own axis once Rotates on its own axis once every 25.4 days at the equator.every 25.4 days at the equator.

Revolves around the center of Revolves around the center of the Milky Way Galaxy once the Milky Way Galaxy once every 225 million years.every 225 million years.

The EarthThe Earth

Diameter: 12.7 thousand Diameter: 12.7 thousand kilometerskilometers

Mass: 6.0 x 10Mass: 6.0 x 102424 kilograms or six kilograms or six sextillion metric tonssextillion metric tons

Composition: water, silicon, Composition: water, silicon, heavy metal iron-nickel coreheavy metal iron-nickel core

Atmosphere: nitrogen, water Atmosphere: nitrogen, water vapor, oxygen, carbon dioxidevapor, oxygen, carbon dioxide

Surface Temperature: -13 – Surface Temperature: -13 – 3737ooCC

Called the “Blue Planet” Called the “Blue Planet” because of the color of nitrogen because of the color of nitrogen in it’s atmosphere.in it’s atmosphere.

Earth’s MovementEarth’s Movement

The Earth rotates on an axis that is tilted 23 The Earth rotates on an axis that is tilted 23 ½½ degrees degrees relative to the orbital or ecliptic plane. relative to the orbital or ecliptic plane.

It’s period of rotation is one day or 23 hours and 56 It’s period of rotation is one day or 23 hours and 56 minutes.minutes.

The period of revolution around the Sun is a year or 365 The period of revolution around the Sun is a year or 365 and one-quarter days.and one-quarter days.

Why do we have leap years every four years?Why do we have leap years every four years? The earth completes this The earth completes this ellipticalelliptical orbit at an average orbit at an average

radius of 150,000,000 kilometers from the Sun. radius of 150,000,000 kilometers from the Sun. It travels through 942 million kilometers of space during its It travels through 942 million kilometers of space during its

ellipticalelliptical orbit, and travels at a speed of 100,000 km per orbit, and travels at a speed of 100,000 km per hour to finish that path in one year.hour to finish that path in one year.

The earth is also wobbling back and forth along its orbit The earth is also wobbling back and forth along its orbit because of the movement of the moon.because of the movement of the moon.

The MoonThe Moon Diameter: 3.4 thousand kilometers Diameter: 3.4 thousand kilometers

(about ¼ of the diameter of the (about ¼ of the diameter of the earth)earth)

Mass: 7.36 × 10Mass: 7.36 × 102222 kilograms or kilograms or about 1/80 of the mass of the earthabout 1/80 of the mass of the earth

Composition: similar to the earth’s Composition: similar to the earth’s crustcrust

Atmosphere: because of little Atmosphere: because of little gravity the moon basically has no gravity the moon basically has no atmosphereatmosphere

Surface covered with craters and Surface covered with craters and mares (flat seas of rock)mares (flat seas of rock)

Surface Temperature: -233 – 123 Surface Temperature: -233 – 123 ooCC

The moon always shows the same The moon always shows the same side to Earthside to Earth

What is the collision theory about What is the collision theory about how the moon was formed?how the moon was formed?

The Movements of the MoonThe Movements of the Moon The Moon rotates on an axis that is not tilted very much The Moon rotates on an axis that is not tilted very much

relative to the Earth. relative to the Earth. It’s period of rotation is 27.3 days.It’s period of rotation is 27.3 days. The period of revolution around the Earth is 27.3 days as it The period of revolution around the Earth is 27.3 days as it

completes a near circular orbit at an average radius of 384,000 completes a near circular orbit at an average radius of 384,000 kilometers.kilometers.

What do these last two facts mean?What do these last two facts mean? That’s right. We are always looking at the same side of the That’s right. We are always looking at the same side of the

moon from the Earth. Actually we can see a little more around moon from the Earth. Actually we can see a little more around the edges, but only 55% of the lunar surface is visible from the the edges, but only 55% of the lunar surface is visible from the earth.earth.

It travels through 2.4 million kilometers of space during its It travels through 2.4 million kilometers of space during its slightly slightly ellipticalelliptical orbit, and travels at a speed of 3700 km per orbit, and travels at a speed of 3700 km per hour to finish that path in one month.hour to finish that path in one month.

The moon looks as much as 11% bigger or smaller because of The moon looks as much as 11% bigger or smaller because of the apogee, perigee, and tilt of its orbit relative to the earth.the apogee, perigee, and tilt of its orbit relative to the earth.

The moon’s orbital plane is 5 degrees tilted compared to the The moon’s orbital plane is 5 degrees tilted compared to the Earths ecliptic plane.Earths ecliptic plane.

Let’s see what you know!!Let’s see what you know!!

Which one is the smallest?Which one is the smallest? Which one is the densest?Which one is the densest? Which one has the greatest mass?Which one has the greatest mass? Which is spinning fastest on its axis?Which is spinning fastest on its axis? Which one is spinning slowest?Which one is spinning slowest? Which one has the longest orbit?Which one has the longest orbit? Which is moving fastest? Be careful on this one!!Which is moving fastest? Be careful on this one!! Now let’s see how they are related!!Now let’s see how they are related!!

The moon is constantly revolving around the The moon is constantly revolving around the Earth as the Earth revolves around the Sun.Earth as the Earth revolves around the Sun.

The appearance of the lit side of the moon The appearance of the lit side of the moon causes a change in the appearance of the causes a change in the appearance of the moon called a phase.moon called a phase.

Lets look closer at phase changes and other Lets look closer at phase changes and other things related to this movement.things related to this movement.

Phases of the MoonPhases of the Moon

The Moon Phases and TidesThe Moon Phases and Tides Tides are periodic rises and falls of large bodies of Tides are periodic rises and falls of large bodies of

water. Tides are caused by the gravitational water. Tides are caused by the gravitational interaction between the Earth and the Moon. interaction between the Earth and the Moon.

The gravitational attraction of the moon causes the The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon the Earth is also being pulled toward the moon (and away from the water on the far side). (and away from the water on the far side).

Since the earth is rotating while this is happening, Since the earth is rotating while this is happening, two tides occur each day. two tides occur each day.

Isaac NewtonIsaac Newton (1642 -1727) was the first person to (1642 -1727) was the first person to explain tides scientifically. His explanation of the explain tides scientifically. His explanation of the tides (and many other phenomena) was published tides (and many other phenomena) was published in 1686, in the second volume of the Principia. in 1686, in the second volume of the Principia.

Take a Look!!Take a Look!!

Variations in TidesVariations in Tides

What two dates would have the highest tides?What two dates would have the highest tides?

How many times a day do high tide How many times a day do high tide and low tide happen? and low tide happen?

Tides at the Chesapeake Bay Bridge TunnelTides at the Chesapeake Bay Bridge Tunnel

2004-04-22 4:47 AM EDT Low Tide 0.20 feet

2004-04-22 10:53 AM EDT High Tide 2.44 feet

2004-04-22 4:38 PM EDT Low Tide 0.24 feet

2004-04-22 11:08 PM EDT High Tide 2.92 feet

2004-04-23 5:24 AM EDT Low Tide 0.34 feet

2004-04-23 11:30 AM EDT High Tide 2.33 feet

2004-04-23 5:16 PM EDT Low Tide 0.35 feet

Besides tides and phases, the Besides tides and phases, the moon’s movement is also moon’s movement is also

responsible for two common responsible for two common events called solar and lunar events called solar and lunar

eclipses.eclipses.

Facts about EclipsesFacts about Eclipses Eclipses are caused by a shadow being Eclipses are caused by a shadow being

cast on the moon or the earth.cast on the moon or the earth.

When the moon cast a shadow on the When the moon cast a shadow on the Earth it is a solar eclipse (The sun is Earth it is a solar eclipse (The sun is blocked from view)blocked from view)

When the Earth casts a shadow on the When the Earth casts a shadow on the moon it is called a lunar eclipse (we can moon it is called a lunar eclipse (we can not see the moon)not see the moon)

Lunar eclipsesLunar eclipses do not occur as do not occur as frequently as total solar eclipses, but frequently as total solar eclipses, but they are visible from anywhere on the they are visible from anywhere on the side of Earth facing the Moon during the side of Earth facing the Moon during the evening. evening. (seen most often(seen most often))

A total solar eclipse can only be seen A total solar eclipse can only be seen from a narrow band about a hundred from a narrow band about a hundred miles wide at most, and while up to miles wide at most, and while up to seven of these a year are not unusual, seven of these a year are not unusual, they frequently occur over the most they frequently occur over the most inaccessible regions on the planet. inaccessible regions on the planet. (most common) (least seen(most common) (least seen))

Even when 99% of the Sun's surface is Even when 99% of the Sun's surface is obscured during the partial phases of a obscured during the partial phases of a total eclipse, the remaining crescent is total eclipse, the remaining crescent is intensely bright and cannot be viewed intensely bright and cannot be viewed safely without eye protection. safely without eye protection. Failure to Failure to use appropriate filtration may result use appropriate filtration may result in permanent eye damage or in permanent eye damage or blindnessblindness. .

Eclipse Schedules - 2004Eclipse Schedules - 2004 Apr. 19Apr. 19. Partial eclipse of the Sun. Visible in Antarctica, southeast Atlantic . Partial eclipse of the Sun. Visible in Antarctica, southeast Atlantic

Ocean, southern half of Africa and Madagascar.Ocean, southern half of Africa and Madagascar.

May 4May 4. Total eclipse of the Moon. The beginning of the umbral phase visible in . Total eclipse of the Moon. The beginning of the umbral phase visible in Asia except extreme northeast, Europe except western region, Africa except Asia except extreme northeast, Europe except western region, Africa except northwestern part, Indonesia, Australia, New Zealand, Antarctica except part of northwestern part, Indonesia, Australia, New Zealand, Antarctica except part of the peninsula, the eastern South Atlantic Ocean, the Indian Ocean, and the the peninsula, the eastern South Atlantic Ocean, the Indian Ocean, and the western Pacific Ocean; the end visible in Africa, Europe, western Asia, western western Pacific Ocean; the end visible in Africa, Europe, western Asia, western Australia, Antactcia, South America except the southwestern part, the eastern Australia, Antactcia, South America except the southwestern part, the eastern North Atlantic Ocean, the South Atlantic Ocean, the Indian Ocean, and the North Atlantic Ocean, the South Atlantic Ocean, the Indian Ocean, and the extreme southeastern South Pacific Ocean.extreme southeastern South Pacific Ocean.

Oct. 14Oct. 14. Partial eclipse of the Sun. Visible in Northeast Asia, Japan, western . Partial eclipse of the Sun. Visible in Northeast Asia, Japan, western Pacific Ocean, Hawaiian Islands, and the western part of Alaska.Pacific Ocean, Hawaiian Islands, and the western part of Alaska.

Oct. 28.Oct. 28. Total eclipse of the Moon. The beginning of the umbral phase visible in Total eclipse of the Moon. The beginning of the umbral phase visible in Africa, Europe, Greenland, the Arctic region, North America except the extreme Africa, Europe, Greenland, the Arctic region, North America except the extreme northwest, Central America, South America, extreme western Asia, part of Queen northwest, Central America, South America, extreme western Asia, part of Queen Maud Land and the peninsula of Antarctica, the Atlantic Ocean, the eastern Maud Land and the peninsula of Antarctica, the Atlantic Ocean, the eastern South Pacific Ocean, and the western Indian Ocean; the end visible in North South Pacific Ocean, and the western Indian Ocean; the end visible in North America, the Arctic region, Greenland, Central America, South America, Europe, America, the Arctic region, Greenland, Central America, South America, Europe, western Africa, Antarctic peninsula, the eastern Pacific Ocean, and the Atlantic western Africa, Antarctic peninsula, the eastern Pacific Ocean, and the Atlantic

Models of Solar EclipsesModels of Solar Eclipses

Model of a Lunar EclipseModel of a Lunar Eclipse

The Earth is moving around the The Earth is moving around the Sun and is tilted on an axis Sun and is tilted on an axis relative to the orbital plane.relative to the orbital plane.

What kinds of things does this What kinds of things does this cause?cause?

What Causes the Seasons?What Causes the Seasons?

Check this out!!Check this out!! In the below animation, you can see the Earth during one In the below animation, you can see the Earth during one

full year (the animation then starts over again), as you full year (the animation then starts over again), as you would if you looked straight at it from the Sun. As you can would if you looked straight at it from the Sun. As you can see, the part of the Earth that is directly facing the sun see, the part of the Earth that is directly facing the sun changes with the time of the year. It is the northern half for changes with the time of the year. It is the northern half for a while, then moves south of the equator, only to move a while, then moves south of the equator, only to move back to the north again. back to the north again.

Kind of makes you dizzy thinking Kind of makes you dizzy thinking about it, doesn’t it?about it, doesn’t it?

A common myth is that the seasons are caused by the A common myth is that the seasons are caused by the changing distance between the Earth and the Sun. changing distance between the Earth and the Sun.

The info below disproves that myth. The info below disproves that myth. The aphelion is the furthest distance from the Sun, and the The aphelion is the furthest distance from the Sun, and the

perihelion is the closest distance to the Sun. perihelion is the closest distance to the Sun. Notice that the perihelion happens during the winter and Notice that the perihelion happens during the winter and

the aphelion in the summer.the aphelion in the summer.

Perihelion Jan 4 18 Aphelion July 5 11 Equinoxes Mar 20 06 49 Sept 22 16 30 Solstices June 21 00 57 Dec 21 12 42

Equinoxes and SolsticesEquinoxes and Solstices

The official date beginnings of the seasons are the The official date beginnings of the seasons are the equinoxes and the solstices. equinoxes and the solstices.

Summer begins on the summer solstice (the longest day of Summer begins on the summer solstice (the longest day of the year)the year)

Fall begins on the autumnal equinox. (equal night 12h/12h)Fall begins on the autumnal equinox. (equal night 12h/12h) Winter begins on the Winter solstice (the shortest day of Winter begins on the Winter solstice (the shortest day of

the year)the year) Spring begins on the vernal equinox. (equal night)Spring begins on the vernal equinox. (equal night) In 2004 these occur on:In 2004 these occur on: Equinoxes Mar 20 06 49 Sept 22 16 30 Solstices June 21 00 57 Dec 21 12 42

What would happen if…What would happen if…

the earth’s axis was not tilted toward or the earth’s axis was not tilted toward or away from the sun?away from the sun?

the earth’s axis was tilted more than 23.5 the earth’s axis was tilted more than 23.5 degrees?degrees?

The earth’s axis was tilted less than 23.5 The earth’s axis was tilted less than 23.5 degrees?degrees?

Time Goes OnTime Goes On

A day is the time it takes for the Earth to complete A day is the time it takes for the Earth to complete one rotation on its axis.one rotation on its axis.

A year is the time it takes for the Earth to complete A year is the time it takes for the Earth to complete one revolution around the sun.one revolution around the sun.

A month is the time it takes for the moon to A month is the time it takes for the moon to complete one revolution around the earth and one complete one revolution around the earth and one rotation on its axis.rotation on its axis.

A week is 7 days long, which is the time it takes to A week is 7 days long, which is the time it takes to go through one phase of the moon.go through one phase of the moon.

Monday is “moon” day, and Sunday is “Sun” dayMonday is “moon” day, and Sunday is “Sun” day What would happen to time measurement if the What would happen to time measurement if the

earth started rotating twice as fast on its axis?earth started rotating twice as fast on its axis?

Do You Understand?Do You Understand?

What causes the seasons?What causes the seasons? Tides are caused by the tilt Tides are caused by the tilt

of the Earth. of the Earth. T or FT or F What are the highest tides What are the highest tides

called?called? If your days are shorter If your days are shorter

than twelve hours long and than twelve hours long and getting shorter all the time getting shorter all the time what season are you?what season are you?

What do we call the What do we call the longest day?longest day?

If your days are longer If your days are longer than twelve hours and than twelve hours and getting longer all the time, getting longer all the time, what season are you?what season are you?

What type of eclipse What type of eclipse happens most often?happens most often?

What type of eclipse is What type of eclipse is seen more often?seen more often?

What calendar time What calendar time periods are related to the periods are related to the movement of the moon?movement of the moon?

Winter Solstice

Dec. 21

Autumnal Equinox

Sept. 22

Summer Solstice

June 21

Vernal Equinox

Mar 20

Perihelion – Jan. 4

Aphelion – July 5

Summer

Winter

Fall

Spring

September

November

October

December

January

March

April

July

August

June

May

February

March 6,1959