Earth, Sun, and MoonEarth, Sun, and Moon

Physical Properties of EarthPhysical Properties of Earth

Diameter (pole to pole) 12,714 km Diameter (equator) 12,756 km Circumference (poles) 40,008 km Circumference (equator) 40,075 km Mass 5.98 x 1027 g Density 5.52 g/cm3 Average distance to sun 149,600,000 km Period of Rotation 23 hr 56 min Period of Revolution 365 days 6 hr 9

min

Motions of the EarthMotions of the Earth

1)1) RotationRotation1.1. Turning or spinning on its axisTurning or spinning on its axis

2)2) RevolutionRevolution1)1) Earth revolving around the sun in an elliptical orbitEarth revolving around the sun in an elliptical orbit

3)3) PrecessionPrecession1)1) Slight movement over a period of 26,000 Slight movement over a period of 26,000

years of Earth’s axisyears of Earth’s axis

RotationRotation 2 ways of measuring2 ways of measuring

1) Solar Day – time from one noon to 1) Solar Day – time from one noon to the nextthe next

2) Sidereal Day- time it takes Earth to 2) Sidereal Day- time it takes Earth to complete one full rotation (360 complete one full rotation (360 degrees) with respect to another star degrees) with respect to another star other than our sunother than our sunTime required for a star to reappear at Time required for a star to reappear at

the identical position in the sky where it the identical position in the sky where it was observed the day beforewas observed the day before

23 hours 56 minutes23 hours 56 minutes

RevolutionRevolutionEarth revolves around the sun in an Earth revolves around the sun in an

elliptical orbit at an average speed elliptical orbit at an average speed of 107,000 kilometers/hourof 107,000 kilometers/hourAverage distance from the sun is 150 Average distance from the sun is 150

million kilometersmillion kilometersPerihelion- Earth is closest to the Perihelion- Earth is closest to the

sun 147 million kilometers away sun 147 million kilometers away (January)(January)

Aphelion- Earth is farthest from the Aphelion- Earth is farthest from the sun about 152 million kilometers sun about 152 million kilometers away (July)away (July)

PrecessionPrecession

Earth wobbles on its 23.5Earth wobbles on its 23.5oo axis and North axis and North pole points to different stars in 26,000 year pole points to different stars in 26,000 year periodperiodNow points towards PolarisNow points towards Polaris In 14,000 will point to VegaIn 14,000 will point to VegaBy 28,000 will point to Polaris againBy 28,000 will point to Polaris againHas a slight affect on seasons Has a slight affect on seasons

SeasonsSeasons

The northern hemisphere experiences summer when Earth is farthest from the sun.

It experiences winter when Earth is closest to the sun.

The seasons are a result of the Earth’s tilt on its axis.Remember Earth’s axis is at a 23.5o tilt.

EquinoxEquinox

Equinox is the time when the sun is directly on Earth’s equator.Number of daytime hours = Number of

nighttime hoursNorthern and Southern Hemispheres are

not tilted toward the sun.Spring Equinox – Around March 20, 21Fall Equinox – September 22, 23

SolsticeSolstice

The point when the sun reaches its greatest distance north or south of the equator.

Summer Solstice – June 21, 22Long days, shorter nights

Winter Solstice – December 21, 22Short days, longer nights

http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html

Earth-Sun MotionEarth-Sun Motion

Earth, Sun, and solar system speeds in Earth, Sun, and solar system speeds in the direction of the bright star Vega at 20 the direction of the bright star Vega at 20 Kilometers per secondKilometers per second

Also- Sun revolves around the galaxyAlso- Sun revolves around the galaxyGalaxies themselves are also in motionGalaxies themselves are also in motion

We are approaching AndromedaWe are approaching Andromeda

Earth’s Moon (Luna)Earth’s Moon (Luna)

Earth’s only natural satellite (objects that Earth’s only natural satellite (objects that are in Earth’s orbit)are in Earth’s orbit)

Density is 3.3X greater than mantle rocks Density is 3.3X greater than mantle rocks of Earthof Earth

Gravitational attraction is 1/6 of that on Gravitational attraction is 1/6 of that on Earth- 150lb on Earth = 25 lb on the moonEarth- 150lb on Earth = 25 lb on the moon

Earth’s MoonEarth’s Moon

The moon rotates on its axis, and revolves around the earth. Moon’s rotations = 1 rotation every 27.3 days Moon’s revolution = 1 rev. every 27.3 days

Because the revolution and rotation times are the same, we always see the same side of the moon.

The moon shines because of light being reflected from the sun. Moon phases are the changing appearances of the

moon as seen from Earth.

Phases of the MoonPhases of the Moon New Moon – the lighted half of the moon is

facing the sun and dark side faces the earth. Occurs when the moon is between Earth and the sun.

Waxing – Shortly after the new moon, more and more of the moon’s lighted side becomes visible (about 24 hours after new moon)

Waxing occurs until we see the full moon

Waning PhasesWaning Phases

Happens after the full moon, when the moon’s lighted side becomes smaller.

Waning gibbous occurs after the full moon.Then third quarter phase occursNext comes waning crescentFinally the waning phase ends with a new

moon.

New MoonNew Moon

Waxing CrescentWaxing Crescent(Anything small than a quarter)(Anything small than a quarter)

First QuarterFirst Quarter

Waxing GibbousWaxing Gibbous(More than one-quarter is visible)(More than one-quarter is visible)

Full MoonFull Moon

Names for the Full MoonNames for the Full Moon January: Wolf or Hunger moon. During this month the wolves once

roamed the countryside, thus suggesting the name wolf moon. In cold and temperate climates of the Northern Hemisphere, it was difficult to find food during January, thus the name hunger moon.

February: Snow Moon. In certain parts of the world, snow is usually the deepest in this month, thus the name snow moon.

March: Sap or Worm Moon. Because sap rises in March, this full moon is called the sap moon. The ground softens during this month, and worms begin to burrow out of the ground, thus the name worm moon.

April: Pink Moon. Many flowers turn pink and bloom in April, thus the name pink moon.

May: Flower Moon. Because many flowers bloom in May, after the April downpours, May's moon is called the flower moon.

June: Strawberry or Rose Moon. Because strawberries bloom in June, this month's moon is the strawberry moon. Also, the French call this moon la lune rose, which translates into English as "the rose moon."  

Names for the Full Moon ContinuedNames for the Full Moon Continued

July: Buck Moon. Male deer, or bucks, grow their first antlers during this month, thus the name buck moon.

August: Sturgeon Moon. Because it is sturgeon season in certain parts of the world in August, its moon is called the sturgeon moon

September: Harvest or Corn Moon. Native Americans began to harvest their crops during this month every year. (If this full moon occurs late in August it is called the harvest moon.). If the full moon occurs earlier in September, it is called the corn moon because the corn crop is ready for picking at that time.

October: Hunter's Moon. The hunting season begins in October, thus the name hunter's moon.

November: Beaver Moon. Beaver traps were once set in this month to catch enough beaver to make warm clothing for the upcoming winter.

December: Cold Moon. The approach of cold weather in the Northern Hemisphere gives this month's full moon its name. Compton's Interactive Encyclopedia

Waning GibbousWaning Gibbous

Third (Last) QuarterThird (Last) Quarter

Waning CrescentWaning Crescent

New MoonNew Moon(Cycle starts over again!!!)(Cycle starts over again!!!)

EclipsesEclipses

Shadow effectsWhen the moon moves in a line directly

between Earth and the Sun it casts a shadow on Earth- Solar Eclipse

When the moon moves within Earth’s shadow- Lunar Eclipse

The revolution of the moon causes eclipsesWhat does the moon revolve around?

Solar EclipsesSolar Eclipses

Umbra – Darkest portion of the moon’s shadow (Total Eclipse)

Penumbra – Surrounds the umbra and is lighter shadow on Earth’s surface (Partial Eclipse)

Caution: Regardless of where you are standing, never look directly at a solar eclipse. The light will permanently damage your eyes.

Lunar EclipseLunar Eclipse

Happens when the shadow of Earth falls on the moon.

Moon moves into Earth’s penumbra.Continues to move, enters the umbra, and

you see a curved shadow on the moon’s surface.

Partial Lunar EclipsePartial Lunar EclipseOnly a portion of the moon moves Only a portion of the moon moves

into Earth’s umbrainto Earth’s umbra

Total Lunar EclipseTotal Lunar Eclipse(January 2000)(January 2000)

Structure of the MoonStructure of the Moon

Don’t believe everything you read.Discovery of life on the Moon was

announced to the American public by the New York Sun in 1835. This fanciful illustration is supposed to have shown what astronomers were seeing with new and more powerful telescopes.

Structures of the MoonStructures of the MoonMaria are dark-colored, relatively flat

regions on the moon. Formed when ancient lava flows from the moon’s

interior filled large basins on the moon’s surface. Some are 3 to 4 Billion years old and are the youngest

rocks on the moon

Highlands- densely pitted light-colored areas

Regolith- soil-like layer composted of igneous rock, glass beads, and fine lunar dust

Maria

Maria

CratersCraters

Most obvious features on the moonDepression formed by meteorites,

asteroids, and comets, which struck the moon.

Cracks have formed in the moon, during impacts

Many more than Earth because the moon has no atmosphere to burn up debris and no destruction by tectonic forces

South Pole of the MoonSouth Pole of the Moon

Surface seen by Apollo 11 on its decent to the moon

Apollo 11Apollo 11

Moon InteriorMoon InteriorCore

Mantle

Crust

Moon’s InteriorMoon’s Interior

Earthquakes allow scientists to map the moon’s interior.Seismographs were left by Apollo astronauts

Crust:60 km thick on the side facing Earth150 km thick on the far side

Mantle: solid mantle, maybe 1000 km thickCore: May be a solid iron-rich core

False Color MosaicFalse Color MosaicTaken by Galileo in 1992Taken by Galileo in 1992

Red = Lunar Highland

Blue & Orange = ancient lava flows

Blue regions contain more titanium than orange

Purple = regions that formed during large volcanic eruptions

Moon dust under microscopeMoon dust under microscope

Mostly titanium and iron oxides

Origins of the MoonOrigins of the Moon

Three popular theories, prior to the Apollo missions:

1. Moon was captured by Earth’s gravity

2. Moon condensed from loose material surrounding Earth during the formation of the solar system.

3. Blob of molten material was ejected from Earth while Earth was still in its early stage.

Impact TheoryImpact Theory

Impact TheoryImpact Theory

Moon formed around 4.6 billion years ago when a Mars-sized object collided with Earth

Melted part of Earth’s Mantle and the impacting object. Material ejected into space

Debris started orbiting the Earth, some debris fell back to Earth

Material formed a ring of hot dust and gas around Earth

In about 100 years, the particles in the ring joined together forming the moon

Future Moon MissionsFuture Moon Missions

Will there be future missions to the moon?Will there be colonies on the moon?How can we sustain life on the moon?

Please take a few moments to think about these questions.