P1 - The Earth In The Universe
- Created by: georgieeeee_5
- Created on: 08-04-16 08:45
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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
- 1. The Solar System
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