SUN, MERCURY, VENUS, EARTH, MARS, ASTEROID BELT, JUPITER, SATURN, URANUS NEPTUNE
- Dwarf planets, comets, dust and moons
- S.S formed over a long period of time from large clouds of dust and gas- gravity took over and collapsed in
- fusion H -> He, releases loads of energy and light
- oldest rocks= meteorites crashed into Earth (4500 million yrs ago)
- Asteroids and comets are made out of 'left over' material from the formation of the S.S
- Rocks between Mars and comets are staged as smallish lumps of rubble and rock- asteroids
- comets= balls of rock, dust and ice- orbit the sun in elongated ellipses, as comet approaches the sun= ice melts, leaves a long tail of gas and debris - kilometers long
Beyond the Solar System
- our sun is one of thousands in the Milky Way, approx 1 in 10 to the 11
- distance between neighbouring stars are a lot greater than distance between neighbouring planets
- whole universe is made of millions of galaxies= lots of empty space and very big
- Distance can be measured using light years
- LIGHT YEAR: DISTANCE LIGHT TRAVELS IN ONE YEAR IN A VACUUM
- Universe= 14000 million y/a
- Sun = 5000 million y/a
- Earth= 5000 million y/a
Looking into Space
- Know a lot about space by studying EM radiation it emits
- Parallax- pictures of the sky six months apart, apparent movement of a star between two points let's you work out the distance- further= moves less
- Relative brightness= comparing brightness of two stars- brighter= usually closer, but it could just be close but not that bright/ far but reaally bright.
- Astronomers know how much radiation is emitted so by examining how bright they look from Earth, they can tell how far away they must be
- Atmosphere and light pollution causes problems, the atmosphere absorbs lots of light, light pollution makes it hard to see dim objects- that's why there's the Hubble telescope in space
- We see galaxies and stars as they were in the past, E.M travels very fast, we see the sun how it was eight minutes ago because it takes that long for EM to travel to Earth from the Sun
Life of the Universe
More distant= faster it moves away
- when a galaxy is moving away, wavelength changes- light becomes redder- redshift. Greater redshifted= greater the speed it'smoving away- provides evidence that the universe is expanding.
- Big Bang Theory- universe is expanding everything seems to be moving apart, started at Big Bang. This theory suggests that all matter and energy was compressed into space, then it exploded and started expanding - expansion is still happening now.
- Age of universe can be estimated from current rate of expansion, so approx. 14 million years ago. But it is difficult because it slows down.
- We don't know fate of universe becsuse... it depends how fast it is expanding and the total mass. It's hard to measure because determining fate is difficult to calculate. How fast it is moving, you need to measure large distances, but universe is huge so it is hard. Also need to observe the motion of objects- have to make assumptions about their motion, pollution interference and v. far away. Dark matter = invisible.
- All mass everywhere is pulled by gravity, more mass=greater the pull= greater the slowing down of the expansion.
The Changing Earth
Earth= active planet
- rocks provide a record of changes in the Earth. Erosion goes on everywhere, cliffs are worn by the sea, but other processes are also happening. Must be things making new rock.
- Fossils also provide evidence rock is constantly forming- animals and plants must have been surrounded by rock and build around them- age can be estimated from rocks- oldest approx. 4 hundered million yrs old- Earth must be at least that old.
- Rocks are contantly recycled
- Rock cycle: particles eroded from existing rock get washed into sea and settle as sediment, over time crushed as sediment. These can get pushed to the surface or can descend into heat and pressure of the Earth, if thet descendheat and pressure caused structure to change. Sometimes rock actually melts, but it will solidify into new rock. Pushed to surface=cycle starts aginand gradually gets warn down and carried off to sea. Rock cycle needs the same v. powerful forces to push rocks up or down.
Wegner's Theory of Continental Drift
- fossils of similar plants and animals found on opposite sides of the world
- people believed this was because of Land Bridges
- continents matched, fossils from sea creatures in mountains
- Wegner= a meteorologist and moving wasn't detectable- also wasn't enough evidence for such a huge theory
- Evidence became overwhelming
- Mid-atlantic ridge, whole length of Atlantic
- Seafloor spreading- magma rises up through sea floor- solidifies
- magnetication of the rocks- magma erupts out of the gap, iron particles in the soil tend to align themselves w. Earth's magnetic field- cools and sets- swaps direction and as a rock either side of the ridge has bonds of alternative magnetic polarity., symmetrical around ridge.
Structure of Earth
- Crust- v. thin 2 types= OCEANIC (under oceans) CONTINENTAL (forming land)
- Mantle= all properties of a solid but it can flow very slowly
- Hear from core and radioactive decay causes mantle to flow in convection currents
- CORE= IRON AND NICKEL
- Earth's surface= tetonic plates
- crust and upper mantle cracked into T.P, causes them to drift movements cause seafloor to spread
- most move a few cm per year relative to eachother
- occassionally plates move suddenly= earthquake- more often at plate edges
- volcanoes form at boundaries between T.P where they meet= magma is produced which rise up to form volcanoes
- plates crash into eachother- moutains formed= processes contribute to rock cycle, pushing up or down where plates collide often- one gets pushed underneath
Earthquakes= different types of seismic waves. They produce wave motions which travel on the surface and inside Earth- recorded with a seismograph.
- seismologists measure the time it takes fot shock waves to reavh each seismograph.
- They note parts of the world that recieve no shock waves
- Waves curve w. increasing depth, when they reach a boundary between layers of the Earth- some will be reflected, also change speed as properties of the mantle and core change direction-refraction. Usually gradual, but can have kinks.
- 1/2 way through- change in direction abrupt change= sudden change in properties from mantle
- SWSZ= shows mantle= solid, except with magma in 'hot spots'
- P= faster in middle of core, suggests inner core is a solid
Wave properties= amplitude, wavelenght, crest, trough, rest
waves=transfer energy, not matter
DISTANCE= SPEED X TIME (m = m/s x s)
WAVE SPEED = FREQ X WAVELENGTH (m/s= Hz x m)
Lower freq = longer wavelength
Higher freq = shorter wavelength