Chapter 24

The Solar SystemThe Solar System

Section ISection I

The Solar SystemThe Solar System

Ideas about the night sky have Ideas about the night sky have changed over timechanged over time

Earth-centered model – early Greeks Earth-centered model – early Greeks thought planets, Sun, Moon, and stars thought planets, Sun, Moon, and stars revolved around Earthrevolved around Earth

Sun-Centered modelSun-Centered modelNicholas Copernicus and Galileo Galilei Nicholas Copernicus and Galileo Galilei

observed that the moon revolved around observed that the moon revolved around Earth and that Earth and other planets Earth and that Earth and other planets revolved around the Sunrevolved around the Sun

Modern ViewModern View

solar system includes Sun, eight planets, solar system includes Sun, eight planets, many small objects.many small objects.

NEBULA THEORY (origin of NEBULA THEORY (origin of solar system)solar system)

a nebula of gas, ice, and dust slowly a nebula of gas, ice, and dust slowly formed in spaceformed in space

A cloud of material in the nebula A cloud of material in the nebula slowly rotated in spaceslowly rotated in space

As the cloud contracted, it grew As the cloud contracted, it grew warmer, triggering a nuclear fusion warmer, triggering a nuclear fusion

reaction that created the Sunreaction that created the Sun

The leftover matter became the The leftover matter became the planets and asteroidsplanets and asteroids

First four inner planets – small and rocky First four inner planets – small and rocky with iron cores.with iron cores.

last four outer planets – large and last four outer planets – large and lightweight …lightweight …

Planet orbits are elliptical and the Sun is Planet orbits are elliptical and the Sun is not directly in the center of the orbits.not directly in the center of the orbits.

Section IISection II

The Inner PlanetsThe Inner Planets

MercuryMercuryClosest to the Sun, smallest planetClosest to the Sun, smallest planet

Weak magnetic field suggests an iron coreWeak magnetic field suggests an iron coreHas many craters and high cliffsHas many craters and high cliffsno true atmosphere, so surface no true atmosphere, so surface

temperatures range from very hot to very temperatures range from very hot to very coldcold

VenusVenussecond from the Sun and similar to Earth second from the Sun and similar to Earth

in size and massin size and mass

extremely dense atmosphere of cloudsextremely dense atmosphere of cloudsCarbon dioxide traps solar energyCarbon dioxide traps solar energy

causes an intense greenhouse effectcauses an intense greenhouse effectResults in surface temperatures between Results in surface temperatures between

450450°C and 475°C°C and 475°C

EarthEarth

average distance between Earth and the average distance between Earth and the Sun is 150 million kmSun is 150 million km

Water exists on surface as solid, liquid, Water exists on surface as solid, liquid, and gasand gas

More than 70% of surface covered with More than 70% of surface covered with waterwater

Atmosphere protects surface from most Atmosphere protects surface from most meteors and Sun’s radiationmeteors and Sun’s radiation

MarsMarsCalled red planet because iron oxide in Called red planet because iron oxide in

rocks makes them reddish-yellowrocks makes them reddish-yellowPolar ice caps made mostly of frozen Polar ice caps made mostly of frozen

carbon dioxide and frozen watercarbon dioxide and frozen water

Has largest volcano in the solar systemHas largest volcano in the solar system

Soil shows NO evidence of life………..Soil shows NO evidence of life………..

perhaps……………perhaps……………

Has gullies and deposits of soil and rocks, Has gullies and deposits of soil and rocks, which may indicate the presence of liquid which may indicate the presence of liquid groundwatergroundwater

Thin atmosphere of mostly carbon dioxideThin atmosphere of mostly carbon dioxideStrong winds caused by differences in Strong winds caused by differences in

temperature between day and nighttemperature between day and night

Is tilted on its axis, which causes seasonsIs tilted on its axis, which causes seasons

Two small moons, Phobos and Two small moons, Phobos and DeimosDeimos

Section IIISection III

The Outer PlanetsThe Outer Planets

JupiterJupiter

fifth planet from the Sun, largest planet in fifth planet from the Sun, largest planet in the solar systemthe solar system

Below atmosphere, liquid hydrogen and Below atmosphere, liquid hydrogen and helium are suspectedhelium are suspected

Solid rocky core may exist below liquid Solid rocky core may exist below liquid levellevel

The Great Red Spot is the most The Great Red Spot is the most spectacular of Jupiter’s many spectacular of Jupiter’s many

constant high-pressure gas stormsconstant high-pressure gas storms

Has ringsHas rings

Has at least 61 moons – four are Has at least 61 moons – four are large and have atmosphereslarge and have atmospheres

IoIo is very volcanically active; the closest is very volcanically active; the closest

large moon to Jupiterlarge moon to Jupiter

EuropaEuropacomposed mostly of rock; may have an composed mostly of rock; may have an

ocean of water under a thick layer of iceocean of water under a thick layer of ice

GanymedeGanymede largest moon in solar system, even larger largest moon in solar system, even larger

than planet Mercurythan planet Mercury

CallistoCallistocratered rock and ice crust may surround cratered rock and ice crust may surround

a salty ocean and rock corea salty ocean and rock core

SaturnSaturnSixth planet from the sun, second largest Sixth planet from the sun, second largest

in the solar system, largest densityin the solar system, largest density

Thick outer atmosphere of hydrogen, Thick outer atmosphere of hydrogen, helium, ammonia, methane, and water helium, ammonia, methane, and water vaporvapor

Might have a small, rocky coreMight have a small, rocky core

Each large ring composed of thousands of Each large ring composed of thousands of ringlets of ice and rock particlesringlets of ice and rock particles

Has at least 31 moonsHas at least 31 moons

Largest moon, Titan, is larger than Largest moon, Titan, is larger than the planet Mercurythe planet Mercury

Thick clouds on Titan prevent scientists Thick clouds on Titan prevent scientists from seeing surface…….from seeing surface…….

UranusUranusSeventh planet from the Sun, large, and Seventh planet from the Sun, large, and

gaseousgaseous

Has thin, dark ringsHas thin, dark ringsAtmosphere of hydrogen, helium, and Atmosphere of hydrogen, helium, and

methanemethaneMethane makes the planet bluish-green in Methane makes the planet bluish-green in

colorcolor

Axis of rotation nearly parallel to Axis of rotation nearly parallel to plane of orbitplane of orbit

NeptuneNeptune

eighth planet from the sun, large and eighth planet from the sun, large and gaseousgaseous

bluish-green colored atmosphere similar to bluish-green colored atmosphere similar to that of Uranusthat of Uranus

Storms on Neptune reveal an active and Storms on Neptune reveal an active and rapidly changing atmosphererapidly changing atmosphere

has at least 11 moons, of which pinkish has at least 11 moons, of which pinkish Triton is largestTriton is largest

A. Comet: dust and rock particles A. Comet: dust and rock particles combined with frozen water, combined with frozen water,

methane, and ammonia.methane, and ammonia.

1. Halley’s comet: orbits Sun 1. Halley’s comet: orbits Sun every 76 years.every 76 years.

2. Oort Cloud: large group of 2. Oort Cloud: large group of comets surrounding solar system comets surrounding solar system

beyond Pluto.beyond Pluto.

3. Amateur astronomers 3. Amateur astronomers discovered Hale-Bopp in 1995.discovered Hale-Bopp in 1995.

4. Comet structure: large dirty 4. Comet structure: large dirty snowball of frozen rock and ice.snowball of frozen rock and ice.

CometsCometsa. Ice and dust vaporize as comet nears a. Ice and dust vaporize as comet nears

Sun.Sun.b. Vaporized material forms bright cloud b. Vaporized material forms bright cloud

called coma around comet nucleus.called coma around comet nucleus.c. Solar wind pushes on gas and dust in c. Solar wind pushes on gas and dust in

the coma, causing the particles to form a the coma, causing the particles to form a tail that always points away from the Sun.tail that always points away from the Sun.

d. Eventually, most of the ice in the d. Eventually, most of the ice in the comet’s nucleus vaporizes, leaving only comet’s nucleus vaporizes, leaving only small particles.small particles.

Comets vaporize and break up Comets vaporize and break up after passing close to the Sun after passing close to the Sun

several times. When the nucleus several times. When the nucleus breaks up, pieces spread out. The breaks up, pieces spread out. The dust and rock fragments are called dust and rock fragments are called

MeteoroidsMeteoroids..

B. (1.) B. (1.) MeteoroidMeteoroid: name given to : name given to small pieces of comet when they small pieces of comet when they

move through space.move through space.

B. (2.) B. (2.) MeteorMeteor: small meteoroid : small meteoroid that burns up in Earth’s that burns up in Earth’s

atmosphere.atmosphere.

B. (3.) Meteor ShowersB. (3.) Meteor Showers: occur when Earth’s : occur when Earth’s orbit passes through a group of meteoroids orbit passes through a group of meteoroids

that enter the atmosphere.that enter the atmosphere.

B. (4.) B. (4.) MeteoriteMeteorite: meteoroid that : meteoroid that strikes Earth.strikes Earth.

C. C. AsteroidAsteroid: rock similar to that : rock similar to that which formed planets.which formed planets.

C. (1.) Most asteroids lie in an C. (1.) Most asteroids lie in an asteroid belt located between Mars asteroid belt located between Mars

and Jupiter.and Jupiter.

Asteroid Info:Asteroid Info:

Jupiter’s gravity may have kept these Jupiter’s gravity may have kept these asteroids from forming a planet.asteroids from forming a planet.

some planets’ moons may be asteroids some planets’ moons may be asteroids pulled from the asteroid belt.pulled from the asteroid belt.

asteroid sizes range from very tiny to 940 asteroid sizes range from very tiny to 940 km in diameter.km in diameter.

Near: The Near Earth Asteroid Rendezvous Near: The Near Earth Asteroid Rendezvous probe indicates asteroid 433 Eros has been probe indicates asteroid 433 Eros has been

in many collisions over time.in many collisions over time.

SPACE STATION PHOTO SPACE STATION PHOTO