P1 - The Earth In The Universe

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  • P1 - The Earth In The Universe
    • 1. The Solar System
      • Planets reflect the sunlight, which is why we can see them
      • The order of the planets are; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune
      • The inner planets, are the closest 4 to the sun
      • The outer planets are the 4 furthest from  the sun
      • Dwarf planets, comets, dust and asteroids are also in orbit around the sun
      • We can see stars because of the light that they emit
      • The sun's diameter is over 100 times bigger than ours
      • The solar system was formed from big clouds of dust and gas
      • The solar system is thought to be 5 thousand million years old
      • Fusion happens in stars and starts when there is a high enough temperature
      • Fusion gives out massive amounts of heat and light
      • Fusion creates new elements with a heavier nucleus, therefore making a heavier atom
      • The oldest rocks on earth are meteorites and are thought to be 4500 million years old
      • Asteroids and comets are made from left over stuff from the formation of the galaxy
      • Comets are balls of rock, dust and ice. They orbit the sun in very elongated ellipses
    • 2. Beyond The Solar System
      • Our sun is one of thousands of stars which form the milky way
      • The universe is made of thousands of millions of galaxies and a galaxy is made up of thousands of millions of stars
      • Distances in space are measured by light years.
      • A light year is the distance that light travels in one year
      • Light travels at 300 000km/s
      • Here are the relative distances; Diameter of the Earth, sun, earth's orbit, solar system, Sun to the nearest star, Milky Way and the distance from the milky way to the nearest galaxy
      • The Earth and the Sun is thought to be 5000 million years old
      • The sun is thought to be 14 000 million years old
    • 3. Looking into space
      • Radiation can tell us a lot about stars and galaxies
      • The colour that a star gives out is a good guide to its surface temperature
      • For nearby stars astronomers use parallax to work out how far away it is
      • For stars that are further away, the brightness is used to find their distance. But it is flawed because;
        • The star could be far away and really bright.
        • The star could be relly close and dim
      • The atmosphere and light pollution can sometimes be a problem
      • We see stars and galaxies as they were in the past, because that is how long it takes for the light to reach us.
      • The Hubble telescope is in space so that light pollution and the atmosphere is not in the way
    • 4. The Life Of The Universe
      • Distant galaxies are moving away from us
      • As galaxies are moving away from us, their wave lengths are changing
      • Red shift is used to calculate how fast a galaxy is moving away from us
      • The more distant the galaxy, the faster it is moving away
      • The Big Bang Theory
        • According to this theory, all of the matter in the universe must have been compacted.
        • The rate of expansion can be calculated and then the age of the universe can be calculated
        • The big bang is thought to have started the expansion of the universe.
        • Most galaxies had started expanding from the same point in the universe
      • The universe's ultimate fate depends on how fast its expanding.
      • The big crunch
        • If there is not enough mass in the universe to keep expanding, it will eventually have to contract
        • The factors involved are very hard to measure
    • 5. The Changing Earth
      • The earth is always changing
      • Rocks and fossils provide evidence for changes in the Earth
      • Erosion goes on EVERYWHERE
      • Rocks are constantly being recycled
        • Particles are eroded from existing rock, which then forms sedimentary rocks.
        • Sediments can either descend into the heat and pressure of the earth or get pushed to the surface
        • The cycle needs very powerful forces to push the rock.
    • 6. Wegner's theory of Continental Drift
      • Observations about the Earth hadn't been explained
      • Wegner hypothesised that Africa and South America had previously one continent. This was because their was matching layers of rock
      • At first the theory wasn't accepted because;
        • The 'land bridge' theory was an easier concept.
        • The movement wasn't large enough to detect
        • Wegner was a meteorologist, not a geologist
      • Eventually the evidence became overwhelming
        • In the 1950's a mid-Atlantic ridge was discovered
        • Evidence was found that magma pushed the sea floor causing it to spread
    • 7. The Structure Of The Earth
      • The Earth has a Crust, Mantle and Core
      • The crust is about 20 km thin
      • The mantle is a semi-solid
      • Heat from the core, causes convection currents in the mantle
      • The core is thought ot be made of mainly iron and nickel
      • The Earth's surface is made up of tectnic plates
      • Earthquakes are caused by the sudden movement of plates
      • Volcanoes are caused from magma pushing the plates up
      • Mountains are formed when plates crash into each other
    • 8. Seismic Waves
      • Earthquakes cause s-waves and p-waves
      • Seismographs measure these waves
      • P-waves
        • Travel through solids and liquids
        • Faster than s-waves
        • Longitudinal
      • S-waves
        • Only travel through solids
        • Transverse
        • Slower than p-waves
      • Some waves reflect when they reach a boundary
      • The waves change speed as the properties change
      • Seismographs tell us what is in the centre of the earth. I.e Solids and liquids
      • Push waves and shake waves
    • 9. Waves - The Basics
      • Wvaes have Amplitude, Wavelength, Frequency and Speed
      • Amplitude - the distance from the rest position to the trough
      • The bigger the amplitude, the bigger the energy
      • Wavelength - From crest to crest
      • 1 Hz = 1 wave per second
      • Transverse waves - The vibrations are at 90 degrees to the direction of travel (EM waves)
      • Longitudinal waves - The vibrations are along the same direction as the wave is travelling (Sound)
      • Wave speed = Frequency X Length

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