Presentation on theme: "Chapter 3 The Solar System. How was it formed l The Nebular Theory l Started as nebula about 5 billion years ago – Composed of hydrogen and helium l Nearby."— Presentation transcript:
Chapter 3 The Solar System
How was it formed l The Nebular Theory l Started as nebula about 5 billion years ago – Composed of hydrogen and helium l Nearby supernova sent shock waves through galaxy – caused gases to be pulled inward – supplied new elements l Shrank to a spinning disk –10 billion kilometers across l Gravity heated center to protostar - the sun
How was it formed l Other matter spun around the new sun l gathered into clumps- protoplanets l Near the sun the light weight gases boiled away – Mercury, Venus, Earth, Mars l In those far away the gases did not boil away – Jupiter, Saturn, Uranus, Neptune – the gas giants
How was it formed l Around the protoplanets smaller clumps formed moons or satellites. l Pluto is thought to be a moon of Neptune that broke away. l Asteroid belt- clumps of rocks between Mars and Jupiter l Jupiters gravity stopped a planet from forming l Oort Cloud- Near the edge clumps of matter- home of comets.
History l People have used the stars for ages. l Used constellations to set planting times l Used constellations to guide travels l Some lights in the sky wandered through the constellations l Called them planets which is Greek for wanderers
Ptolemy l Greek scientist l Placed earth at center of universe l Other objects moved in orbits around the earth l Because circle was considered a perfect shape, thought they moved in circular paths
Copernicus l Polish astronomer l Found Earth and planets revolved around sun l In the same direction l At different speeds l Thought the orbits were circular
Kepler l German mathematician and astronomer l Used others observations (Tycho Brahe) l Calculated the orbits of planets were ovals or ellipses l Closer to the sun - shortest time of orbit l Farther from the sun - greater time
Planets l Move in an elliptical orbit
Planets l Period of revolution l the time it takes to go once around the sun l one year l Mercury 88 days, Pluto 248 years
What keeps them there? l Law of inertia - objects motion wont change unless acted upon by an outside force. l Wont change speed or direction l Why do they curve? l Gravity pulls them toward the sun
What keeps them there? Inertia Gravity
Rotation l Planets spin on their axes l One rotation is a day l Mercury 58 days, Jupiter 10 hours
Special Features of the Planets l Mercury l Many Craters – no atmosphere – no erosion l Slow rotation makes it hot and cold
Venus l Thick atmosphere of carbon dioxide l Sulfuric acid clouds l Greenhouse effect – carbon dioxide traps heat. – Makes Venus hotter than Mercury l Retrograde rotation - rotates backward
Mars l Red planet- covered by iron oxide (rust) l Mons Olympus - l Largest volcano in the solar system l Two ice caps – north - water -never melts – south -carbon dioxide melts in summer
Two moons of Mars Phobos Deimos
l Largest of the gas giants l Huge storms - red spot l Small solid core l Liquid metal layer makes a huge magnetic field l Magnetosphere l Gives off more heat than it receives from the sun l Thin ring
Jupiter l Gives off more heat than it receives from the sun. l By far the largest planet.
16 moons l 4 seen by Galileo helped change science
Saturn l Similar to Jupiter l Clouds, magnetosphere, gives off heat l Rotates in 10 hours - makes it bulge in the middle and flat at the poles l Low density- would float in water
Saturn l Many rings – complex system – made of water – weave in and out
Saturn l Many moons - l Titan- the largest is like the early Earth.
Uranus l Twice as far from the sun as Saturn. l Covered with ocean of superheated water l Tilted on axis l Rings of methane ice l Many moons
Neptune l Like Uranus l Hydrogen and helium atmosphere l Surface of water and methane l Rings made of dust l Eight moons
Triton l Large moon l Thought to be captured l Retrograde revolution l out of plane of Neptunes rotation
Pluto l Moon sized l Made of methane l Pink atmosphere on the sunny side l Moon Charon 1/2 the size of Pluto l Scientists think it is a moon broken away from Neptune – Orbit crosses Neptune – Orbit not in plane with other planets
Other Stuff l Meteor- the shooting star -the light you see the sky l Meteoroid- solid rocky objects circling the sun l Meteorite- When a meteor hits the ground l Most dont because they burn up in the atmosphere l Some meteoroids are iron and nickel l Some are stony l Others are combinations
Meteorites l Leave a crater where they hit the ground l Meteorite Crater in Arizona l Evidence of meteorites from the moon and from Mars
Comets l Chunks of dust and gas from the Oort Cloud that orbit the sun l When it gets close to the sun it gets hotter l Some of the gas and dust form a cloud around the head called the coma l Solar wind pushes the gases away from the sun and make the tail l Tail is pushed by the solar wind l Tail always points way from the sun
Solar wind Nucleus Coma Tail
Comets l Comets orbit the sun l Long period comets take a long time to go around – Thousands of years l Short period comets return every few years – Halleys every 75 to 79 years – Last time in 1986 l Suspect a nearby star disrupts the Oort cloud to send more comets toward sun.
Asteroids l Chunks of planetlike material floating in space l Most between Mars and Jupiter l Most 1km in diameter l Ceres- 1000km in diameter l Some pass near Earth l Caused craters on moon, and inner planets
Looking for life l On other planets l Need liquid water and moderate temperatures. l Earth is just the right distance to have the right temperatures l Looking for evidence of former life on Mars- used to have water. l On Titan atmosphere like early earth.
Rockets l Rely on Netwons Third law of Motion – For every action there is an equal and opposite reaction. l Reward blast of hot gases causes rocket to shoot forward. l First developed by Chinese in 1000 – Tube full of gunpowder with cap on one end.
Escape Velocity l The minimum speed needed to leave the gravitational pull. l Depends on mass of planet and distance from the center of planet. – Earth 11.2 km/sec – Moon 2.3 km/sec – Jupiter 63.4 km/sec – Pluto 0.3 km/sec – Sun 616 km/sec
Rockets and Escape Velocity l Solid rockets burn up fuel quickly – Large thrust early – Gravity eventually slows them down. l Liquid fuels provide continuous thrust. – Goddard- gasoline and liquid oxygen – Space shuttle liquid hydrogen and liquid oxygen l Multiple stages to reduce weight.
Spacecraft l Probes have gone past all the planets except Pluto l Have sampled comets tails l Have taken pictures of planets and moons.