Chapter 8 The Solar System

How was it formed The Nebular Theory Started as nebula about 5 billion years ago Composed of hydrogen and helium Nearby supernova sent shock waves through galaxy caused gases to be pulled inward supplied new elements Shrank to a spinning disk –10 billion kilometers across Gravity heated center to protostar - the sun

How was it formed Other matter spun around the new sun gathered into clumps- protoplanets Near the sun the light weight gases boiled away Mercury, Venus, Earth, Mars In those far away the gases did not boil away Jupiter, Saturn, Uranus, Neptune the gas giants

How was it formed Around the protoplanets smaller clumps formed moons or satellites. Pluto is thought to be a moon of Neptune that broke away. Asteroid belt- clumps of rocks between Mars and Jupiter Jupiter’s gravity stopped a planet from forming Oort Cloud- Near the edge clumps of matter- home of comets.

The Origin of the Moon Giant Impact Hypothesis A very large body crashed into the Earth. Debris from the impact made a moon.

4.6 byr ago -- Moon formed, possibly due to collision of Earth and a large, Mars-sized object. If Earth already differentiated, most material expelled would be mantle material, not iron core

Rock at impact heated, losing volatile elements Some debris falls back to Earth, some forms Moon. Earth and Moon each pulled back into spherical shape by gravity.

Why Do We Think This? The moon has no iron Earth’s iron had already concentrated in the core by the time of the impact The iron core of the impactor melded with that of the Earth, leaving the moon with no iron of its own The moon and Earth share isotopes of oxygen that are not found on other planets or objects far from Earth

Surface Features on the Moon Two types of Surfaces Highlands More heavily cratered  surface is older. Maria (“Seas”) Less heavily cratered  surface is younger.

2 Bulges from Gravitational Attraction & Centrifugal Force What causes tides? 2 Bulges from Gravitational Attraction & Centrifugal Force

Gravitational Attraction All masses are drawn to each other. The moon because of its closeness to the Earth exerts a greater gravitational effect on the Earth than the Sun, despite the fact that the Sun is much more massive than the Moon.

Centrifugal Force unequal masses of Earth and Moon second tidal bulge center of rotation lies beneath the Earth’s surface. second tidal bulge ocean shifts away from center of rotation AWAY from center can be observed in action on a passenger riding in a car. If the car swerves around a corner, the passenger's body pushes against the outer edge of the car

Special Features of the Planets Mercury Many Craters no atmosphere no erosion Slow rotation makes it hot and cold

Venus Thick atmosphere of carbon dioxide Sulfuric acid clouds Greenhouse effect carbon dioxide traps heat. Makes Venus hotter than Mercury Retrograde rotation - rotates backward

Mars Red planet- covered by iron oxide (rust) Mons Olympus - Largest volcano in the solar system Two ice caps north - water -never melts south -carbon dioxide melts in summer

Two moons of Mars Phobos Deimos

Jupiter

Jupiter Largest of the gas giants Huge storms - red spot Small solid core Liquid metal layer makes a huge magnetic field Magnetosphere Gives off more heat than it receives from the sun Thin ring

16 moons 4 seen by Galileo helped change science

Saturn Similar to Jupiter Clouds, magnetosphere, gives off heat Rotates in 10 hours - makes it bulge in the middle and flat at the poles Low density- would float in water

Saturn Many rings complex system made of water weave in and out

Saturn Many moons - Titan- the largest is like the early Earth.

Uranus Twice as far from the sun as Saturn. Covered with ocean of superheated water Tilted on axis Rings of methane ice Many moons

Neptune Like Uranus Hydrogen and helium atmosphere Surface of water and methane Rings made of dust Eight moons

Triton Large moon Thought to be captured Retrograde revolution out of plane of Neptune’s rotation

Pluto Moon sized Made of methane Pink atmosphere on the sunny side Moon Charon 1/2 the size of Pluto Scientists think it is a moon broken away from Neptune Orbit crosses Neptune Orbit not in plane with other planets

The Sun An average star Over 1 million earth’s would fit inside 1/4 the density of the Earth made of 4 layers

Corona- Outermost layer Temp-1,700,000ºC Few particles Chromosphere- middle of atmosphere Temp-27,800ºC 1000’s of km thick

Photosphere- Temp-6000ºC 550 km thick Surface of the sun Core- 1,000,000ºC 15,000,000ºC

Activity on the Sun Storms on the sun Prominences- Loops or arches of gas that rise from the chromosphere Solar Flares- Bright bursts of light, huge amounts of energy released Sunspots- Dark areas on the suns surface in the lower atmosphere Motion shows the rotation of the sun Interferes with radio

Meteorites Leave a crater where they hit the ground Meteorite Crater in Arizona Evidence of meteorites from the moon and from Mars

Comets Chunks of dust and gas from the Oort Cloud that orbit the sun When it gets close to the sun it gets hotter Some of the gas and dust form a cloud around the head called the coma Solar wind pushes the gases away from the sun and make the tail Tail is pushed by the solar wind Tail always points way from the sun

Solar wind Coma Tail Nucleus