Earth’s Place in SpaceEarth’s Place in Space

• Earth rotates and revolves around the Sun, Earth rotates and revolves around the Sun, even though it appears as though the Sun is even though it appears as though the Sun is moving!moving!• Rotation – spinning of Earth on its axis, which Rotation – spinning of Earth on its axis, which

occurs once every 24 hoursoccurs once every 24 hours• Earth moves around the Sun in a regular, curved Earth moves around the Sun in a regular, curved

path called an orbitpath called an orbit• It takes one year for Earth’s revolution around the It takes one year for Earth’s revolution around the

SunSun• SEASONS occur due to Earth’s tilted axis and its SEASONS occur due to Earth’s tilted axis and its

revolution around the Sun revolution around the Sun

Our Solar SystemOur Solar System

• Earth orbits the Sun as the solar system Earth orbits the Sun as the solar system revolves within the Milky Way, which is revolves within the Milky Way, which is among billions of galaxies that make up among billions of galaxies that make up the universethe universe

• Introduction to the Solar System – Introduction to the Solar System – VIDEO CLIPVIDEO CLIP

The SeasonsThe Seasons• Change of seasons is a result of the Change of seasons is a result of the tilttilt of the of the

Earth’s rotation axis with respect to the plane Earth’s rotation axis with respect to the plane of the of the eclipticecliptic

• Sun, moon, planets run along the Sun, moon, planets run along the ecliptic ecliptic

Motion of the MoonMotion of the Moon• Moon shines not by its own light but by reflected light of SunMoon shines not by its own light but by reflected light of Sun• Moon revolves around the EarthMoon revolves around the Earth• Moon’s period of rotation = 27.3 days Moon’s period of rotation = 27.3 days

• Period of revolution =Period of revolution =also also 27.3 days27.3 days• The Moon’s changing shapes are known as phasesThe Moon’s changing shapes are known as phases

Phases of the Moon (THE LUNAR CYCLE) – caused by the Phases of the Moon (THE LUNAR CYCLE) – caused by the position of the Earth, the Moon, and the Sun; new to full = waxing; position of the Earth, the Moon, and the Sun; new to full = waxing; full to new = waningfull to new = waning

Phases of the Moon – caused by the position of the Earth, the Phases of the Moon – caused by the position of the Earth, the Moon, and the Sun; new to full = waxing; full to new = waningMoon, and the Sun; new to full = waxing; full to new = waning

……and the phases…with oreos!and the phases…with oreos!

EclipsesEclipses

• One celestial object hidden by other or in the One celestial object hidden by other or in the shadow of anothershadow of another

• Solar eclipse: sun hidden by the Moon, as Solar eclipse: sun hidden by the Moon, as Moon is between the Sun and Earth and the Moon is between the Sun and Earth and the Moon’s shadow falls on EarthMoon’s shadow falls on Earth

• Lunar eclipse: Earth is between the Moon and Lunar eclipse: Earth is between the Moon and the Sun and Earth’s shadow falls on the Moonthe Sun and Earth’s shadow falls on the Moon

• Also: eclipses of Jupiter’s moons, etc.Also: eclipses of Jupiter’s moons, etc.• Most spectacular because moon and sun Most spectacular because moon and sun

appear appear to be the same size from earthto be the same size from earth

Solar Eclipses Solar Eclipses

• UmbraUmbra – region of total shadow – region of total shadow• PenumbraPenumbra – region of partial shadow – region of partial shadow• Totality lasts only a few minutes!Totality lasts only a few minutes!

Solar CoronaSolar Corona

Lunar Eclipses Lunar Eclipses Moon moves Moon moves

into earth’s into earth’s shadow…shadow…

OUR SOLAR SYSTEMOUR SOLAR SYSTEM

THE MILKY WAYTHE MILKY WAY

Free powerpoints at http://www.worldofteaching.com

Our Solar System is filled with Our Solar System is filled with eight major planets, the Sun, and eight major planets, the Sun, and other objects that orbit the Sunother objects that orbit the Sun

• MercuryMercury• VenusVenus• EarthEarth• MarsMars• JupiterJupiter• SaturnSaturn• UranusUranus• NeptuneNeptune• Pluto (not classified as a Pluto (not classified as a

planet any longer!)planet any longer!)

Measuring SpaceMeasuring Space

• Distances in space are so vast they Distances in space are so vast they require different units of measurement require different units of measurement than are used to measure things on than are used to measure things on Earth.Earth.

• An astronomical unit (AU) is about 150 An astronomical unit (AU) is about 150 million km (93,000,000 miles), the mean million km (93,000,000 miles), the mean distance from Earth to the Sundistance from Earth to the Sun

THE SUNTHE SUN

The SunThe Sun

• The Sun is one of one-hundred billion stars in The Sun is one of one-hundred billion stars in our galaxy.our galaxy.

• It is the brightest object in the sky.It is the brightest object in the sky.• Its diameter is 1,390,000 km.Its diameter is 1,390,000 km.• The suns mass is 1.989e30 kg.The suns mass is 1.989e30 kg.• The temperature is 5800 k on the surface and The temperature is 5800 k on the surface and

15,600,000 k at the core.15,600,000 k at the core.• The sun is by far the largest object in our The sun is by far the largest object in our

solar system.solar system.

Inner PlanetsInner Planets

• Solid, with minerals similar to those on Solid, with minerals similar to those on EarthEarth

• Include Mercury, Venus, Earth, and Include Mercury, Venus, Earth, and MarsMars

MERCURYMERCURY

MercuryMercury

• Mercury is the closest planet to the sun and is the Mercury is the closest planet to the sun and is the smallest planet now that Pluto is deemed a “dwarf smallest planet now that Pluto is deemed a “dwarf planet”planet”

• It orbits 57,910,000 km from the sun.It orbits 57,910,000 km from the sun.• Mercury’s diameter is 4,880 kmMercury’s diameter is 4,880 km• The mass of this planet is 3.30e23 kgThe mass of this planet is 3.30e23 kg• Little atmosphere, resulting in extremes of Little atmosphere, resulting in extremes of

temperature; can reach 430 degrees Celsius during temperature; can reach 430 degrees Celsius during the day and drop to –180 degrees Celsius at night!the day and drop to –180 degrees Celsius at night!

Mercury FactsMercury Facts

VENUSVENUS

VenusVenus

• Venus is the third brightest object in the sky.Venus is the third brightest object in the sky.• It is the second closest planet from the sun and is the It is the second closest planet from the sun and is the

sixth largest.sixth largest.• It orbits 108,200,000 km from the sun.It orbits 108,200,000 km from the sun.• Its diameter is 12,103.6 km.Its diameter is 12,103.6 km.• Venus’ mass is 4.869e24 kg.Venus’ mass is 4.869e24 kg.• Heavy cloud layer; clouds trap solar energy, making Heavy cloud layer; clouds trap solar energy, making

the planet extremely hot ~ 470 degrees Celsiu!the planet extremely hot ~ 470 degrees Celsiu! Venus FactsVenus Facts

EARTHEARTH

EarthEarth

• Earth is the third planet from the sun and is the Earth is the third planet from the sun and is the fifth largest.fifth largest.

• It orbits 149,600,000 km from the sun.It orbits 149,600,000 km from the sun.• Its diameter is12,756.3 km.Its diameter is12,756.3 km.• Earth’s mass is 5.972e24 kg.Earth’s mass is 5.972e24 kg.• This planet is the densest major body in our This planet is the densest major body in our

solar system.solar system.• Atmosphere allows life to flourish; water exists Atmosphere allows life to flourish; water exists

as a solid, liquid, and gasas a solid, liquid, and gas Earth FactsEarth Facts

MARSMARS

MarsMars• Mars is the fourth planet from the sun and is the seventh Mars is the fourth planet from the sun and is the seventh

largest.largest.• It orbits 227,940,000 km from the sun.It orbits 227,940,000 km from the sun.• Its diameter is 6,794 km.Its diameter is 6,794 km.• Its mass is 6.4219e23.Its mass is 6.4219e23.• The first space craft to visit Mars was the Mariner 4 in The first space craft to visit Mars was the Mariner 4 in

1965.1965.• Has seasons and polar ice caps; may have water shaping Has seasons and polar ice caps; may have water shaping

its surfaceits surface• Red due to rocks containing iron oxideRed due to rocks containing iron oxide• Two small moons – Phobos and DeimosTwo small moons – Phobos and Deimos Exploring MarsExploring Mars

Asteroid BeltAsteroid Belt

• Separates the inner (rocky) and outer (gas Separates the inner (rocky) and outer (gas giants with lots of moons and rings) planets giants with lots of moons and rings) planets

• Pieces of rock made of minerals similar to Pieces of rock made of minerals similar to those that formed the rocky planets and those that formed the rocky planets and moonmoon

• Jupiter’s huge gravitational force might have Jupiter’s huge gravitational force might have prevented a small planet from forming in the prevented a small planet from forming in the area of the asteroid beltarea of the asteroid belt

JUPITERJUPITER

JupiterJupiter

• Jupiter is the fifth planet from the sun and is Jupiter is the fifth planet from the sun and is by far the largest planet.by far the largest planet.

• It orbits 778,330,000 km from the sun.It orbits 778,330,000 km from the sun.• Its diameter is 142,984 km.Its diameter is 142,984 km.• Its mass is 1.900e27 kg.Its mass is 1.900e27 kg.• Jupiter is the fourth brightest object in the sky.Jupiter is the fourth brightest object in the sky.• 28 moons; Giant Red Spot is a giant storm on 28 moons; Giant Red Spot is a giant storm on

the planet’s surfacethe planet’s surface Jupiter FactsJupiter Facts

SATURNSATURN

SaturnSaturn

• Saturn is the sixth planet from the sun and is Saturn is the sixth planet from the sun and is the second largest.the second largest.

• It orbits 1,429,400,000 km from the sun.It orbits 1,429,400,000 km from the sun.• Its diameter is 120,536 km.Its diameter is 120,536 km.• The mass of Saturn is 3.68e26 kg.The mass of Saturn is 3.68e26 kg.• Saturn is the least dense of all the planetsSaturn is the least dense of all the planets• Has 30 moons; several broad rings of ice and Has 30 moons; several broad rings of ice and

dust.dust. Saturn FactsSaturn Facts

URANUSURANUS

UranusUranus

• Uranus is the seventh planet from the sun and Uranus is the seventh planet from the sun and the third largest.the third largest.

• It orbits 2,870,990,000 km from the sun.It orbits 2,870,990,000 km from the sun.• Its diameter is 51,118 km.Its diameter is 51,118 km.• The mass is 8.683e25 kg.The mass is 8.683e25 kg.• Uranus has only been visited one time, by the Uranus has only been visited one time, by the

Voyager 2 in 1986.Voyager 2 in 1986.• Axis makes the planet spin nearly sideways; has Axis makes the planet spin nearly sideways; has

rings and 21 moonsrings and 21 moons Exploring UranusExploring Uranus

NEPTUNENEPTUNE

NeptuneNeptune

• Neptune is the eighth planet from the sun and Neptune is the eighth planet from the sun and is the fourth largest.is the fourth largest.

• It orbits 4,504,000,000 km from the sun.It orbits 4,504,000,000 km from the sun.• Its diameter is 49,532 km.Its diameter is 49,532 km.• Its mass is 1.0247e26 kg.Its mass is 1.0247e26 kg.• Neptune has 8 moons.Neptune has 8 moons.• Atmosphere is composed of hydrogen, Atmosphere is composed of hydrogen,

helium, and methane (make planet blue)helium, and methane (make planet blue) Neptune FactsNeptune Facts

PLUTOPLUTO

PlutoPluto

• Pluto is the farthest object from the sun Pluto is the farthest object from the sun and is by far the smallest.and is by far the smallest.

• It orbits 5,913,520,000 km from the sun.It orbits 5,913,520,000 km from the sun.• Its diameter is 2274 km.Its diameter is 2274 km.• Its mass is 1.27e22 kg.Its mass is 1.27e22 kg.• Pluto is the only dwarf planet that has Pluto is the only dwarf planet that has

not been visited by a space craft.not been visited by a space craft. Exploring PlutoExploring Pluto

All planets move in same plane All planets move in same plane except Plutoexcept Pluto

Pluto’s strange OrbitPluto’s strange Orbit• Very far out there: 40 A.U.Very far out there: 40 A.U.• Pluto’s year = 248 Earth Pluto’s year = 248 Earth

yearsyears• Orbit inclined 17Orbit inclined 17° w.r.t. ° w.r.t.

eclipticecliptic

• Very eccentric orbit:• Perihelion: 30 A.U.

(inside the Neptune orbit!)

• Aphelion: 50 A.U.

Is Pluto a planet?Is Pluto a planet?

• Orbit too Orbit too weirdweird

• Too smallToo small

• Today Pluto Today Pluto may not be may not be classified as classified as a planet.a planet.

Why do all planets move in Why do all planets move in the same plane? the same plane?

• Reason: Reason: Formation Formation process of the Solar process of the Solar System System

• Condenses from a rotating Condenses from a rotating cloud of gas and dustcloud of gas and dust• Conservation of angular Conservation of angular

momentum flattens itmomentum flattens it• Dust helps cool the nebula Dust helps cool the nebula

and acts as seeds for the and acts as seeds for the clumping of matterclumping of matter

Formation of PlanetsFormation of Planets

• Orbiting dust – Orbiting dust – planitesimalsplanitesimals

• Planitesimals collidePlanitesimals collide• Different elements form in Different elements form in

different regions due to different regions due to temperaturetemperature

• AsteroidsAsteroids• Remaining gasRemaining gas

What’s What’s upup in the night sky? in the night sky? The Celestial The Celestial

SphereSphere• A Geocentric model A Geocentric model

((Earth Centered Universe)Earth Centered Universe)

• Axis through Earth’s Axis through Earth’s north and south pole north and south pole goes through goes through celestial north and celestial north and south polesouth pole

• Earth’s equatorEarth’s equator Celestial Celestial

equatorequator

The Zodiac throughout the YearThe Zodiac throughout the Year(Heliocentric)(Heliocentric)

In Winter sun in Sagittarius, Gemini at night skyIn Winter sun in Sagittarius, Gemini at night sky

In Summer sun in Gemini, Sagittarius at night skyIn Summer sun in Gemini, Sagittarius at night sky

Constellations of StarsConstellations of Stars

• About About 50005000 stars visible with naked eye stars visible with naked eye• About About 35003500 of them from the northern hemisphere of them from the northern hemisphere• Stars that Stars that appearappear to be close are grouped together to be close are grouped together

into into constellationsconstellations since antiquity since antiquity • Officially 88 constellations Officially 88 constellations

(with strict boundaries for classification of objects)(with strict boundaries for classification of objects) • Names range from Names range from

• mythologicalmythological (Perseus, Cassiopeia)(Perseus, Cassiopeia)• technical (Air Pump, Compass)technical (Air Pump, Compass)

Constellations of Stars Constellations of Stars

Orion as seen at night Orion as imagined by menOrion as seen at night Orion as imagined by men

Constellation Orion DistancesConstellation Orion Distances

Stars in a constellation are not connected Stars in a constellation are not connected by relative distances.by relative distances.

Zodiacal signs vs. Zodiacal signs vs. ConstellationsConstellations

- 3603600/12=30/12=300 Each zodiacal sign is exactly 30 degreesach zodiacal sign is exactly 30 degrees- 0 degrees: 0 degrees: Aries Aries - 30 degrees: 30 degrees: TaurusTaurus- 60 degrees: 60 degrees: Gemini Gemini - 90 degrees: 90 degrees: CancerCancer

•“Constellation” is a modern, well-defined term

- Some constellations are big, some are small on the celestial sphere

•“Zodiacal sign” is the old way of dividing the year and the Sun’s path into 12 equal parts

CometsComets

• Large body of frozen ice and rock that travels Large body of frozen ice and rock that travels toward the center of the solar systemtoward the center of the solar system

• As a comet approaches the Sun, radiation As a comet approaches the Sun, radiation vaporizes some of the material; solar winds blow vaporizes some of the material; solar winds blow vaporized gas and dust away from the comet, vaporized gas and dust away from the comet, forming what appears from Earth as a bright, forming what appears from Earth as a bright, glowing tailglowing tail

• Comets originate in the Oort Cloud beyond the Comets originate in the Oort Cloud beyond the orbit of Pluto; some comets may come from orbit of Pluto; some comets may come from the Kuiper beltthe Kuiper belt

MeteoritesMeteorites

• Fragments of space material that land Fragments of space material that land on Earth’s surfaceon Earth’s surface

• Pieces may be iron, rock, or bothPieces may be iron, rock, or both• Age (4.5 billion years) provides a clue to Age (4.5 billion years) provides a clue to

the Solar System’s agethe Solar System’s age

ConstellationsConstellations

• Groups of stars that form a pattern in Groups of stars that form a pattern in the sky; named after animals, objects, the sky; named after animals, objects, and people – real or imaginaryand people – real or imaginary

Lives of StarsLives of Stars

• A star has a life that depends on its sizeA star has a life that depends on its size• When a medium-sized star like the Sun uses When a medium-sized star like the Sun uses

up some of the gases in its center, it up some of the gases in its center, it expands to become a giant star; Sun will expands to become a giant star; Sun will become a giant in about 5 billion years and become a giant in about 5 billion years and will expand to cover the orbits of Mercury, will expand to cover the orbits of Mercury, Venus, and possibly EarthVenus, and possibly Earth

• Sun will lose its outer shell, shrink to a hot Sun will lose its outer shell, shrink to a hot white dwarf, and eventually cool and become white dwarf, and eventually cool and become a black dwarfa black dwarf

Lives of Stars, cont.Lives of Stars, cont.

• Stars begin their lives as huge clouds of gas Stars begin their lives as huge clouds of gas and dustand dust

• Force of gravity causes dust and gases to Force of gravity causes dust and gases to move closer togethermove closer together

• Temperatures within the cloud begin to riseTemperatures within the cloud begin to rise• Star is formed when this cloud gets so dense Star is formed when this cloud gets so dense

and hot that the atoms within it merge (fusion)and hot that the atoms within it merge (fusion)

SupergiantsSupergiants

• When a large star begins to use up the fuel in When a large star begins to use up the fuel in its core, it becomes a supergiantits core, it becomes a supergiant

• Over time, the core collapsesOver time, the core collapses• Supernova occurs, in which the outer part of Supernova occurs, in which the outer part of

the star explodes and becomes bright; core is the star explodes and becomes bright; core is now a neutron starnow a neutron star

• If neutron star is massive enough, it could If neutron star is massive enough, it could become a black holebecome a black hole

• Black holes are so dense that even light Black holes are so dense that even light cannot escape their gravity cannot escape their gravity

GalaxiesGalaxies

• Group of stars, gas, and dust held together Group of stars, gas, and dust held together by gravityby gravity• Elliptical-shaped galaxies are most commonElliptical-shaped galaxies are most common• Spiral galaxies look like a pinwheelSpiral galaxies look like a pinwheel• Irregular galaxies are smaller and less Irregular galaxies are smaller and less

common than other galaxiescommon than other galaxies• Earth is in a spiral galaxy called the Milky WayEarth is in a spiral galaxy called the Milky Way

Speed of Light/Light-YearsSpeed of Light/Light-Years

• Light travels through space at 300,000 Light travels through space at 300,000 km/s – so fast it could go around Earth km/s – so fast it could go around Earth seven times in one secondseven times in one second

• Light-Year: distance light travels in one Light-Year: distance light travels in one year (9.5 trillion km)year (9.5 trillion km)

• 100 billion galaxies might exist ~ all 100 billion galaxies might exist ~ all these galaxies with all their stars make these galaxies with all their stars make up the UNIVERSE!up the UNIVERSE!

Here are some more great sites Here are some more great sites for learning about Planetsfor learning about Planets

The Nine Planets The Nine Planets

Exploring the Planets Exploring the Planets

Welcome to the PlanetsWelcome to the Planets