Download - P1 Earth + the Universe
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P1 Earth + the
Universe
Revision Notes
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Earth + Space
Universe 14000myo
Galaxies star collections
(Milky Way) Solar system 5000myo
Created when dust and gas
pulled together by gravity
making clumps.
Sun is a star; Made of hot gases
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Dating the Earth
Rocks change very slowly due to erosion
and weathering. Deeper the rock the older it is.
Radioactive dating; Estimating the age of something like a rock by
measuring its radioactivity.
Also used on fossils (stony remains of an animal or
plant that lived millions of years ago).
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Continental
Drift
Originally described in 1915 by AlfredWegener(a meteorologist).
Idea that crust consists of a number of
tectonic plates which constantly move Either away from, against or alongside each other.
Move between 2 and 20cm a year.
Now measured using satellites.
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Wegeners Theory
In favour; Fossils and rocks
identical in Africa and
South America.
Continents fit like a
jigsaw.
Land bridge;
Rocks lightest at the topcannot sink into heavier
rocks.
Against;
You cannot see or feelcontinents moving.
Land bridge could
have joined Africa and
S America.Wegener not a
geologist (rock expert).
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Seafloor Spreading
Theory now accepted after initial criticism.
Proved by mapping major oceans. Ridges(mountain chains) down the centre of oceansemit molten lava which cools to make new rock(Constructive margin).
This is constantly pushed along to make way fornewer rock. Shown by magnetic stripes of theEarths field direction of the time.
Discovered by scientist Fred Vine (1963).
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Geohazards
Occur at plate boundaries; Earthquakes, Volcanoes
Landslides, Floods, Tsunamis Government Actions;
Geohazard prediction technology Educate people in what to do.
Building regulations (reduce chance of buildingscollapsing).
Emergency plans/staff training.
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Collision!
A few times during Earths history a massive
asteroid (dwarf rocky planet) orcomet (ball offrozen gases and water) has struck.
Meteorites (tiny dust grains) regularly hit.
Craters seen on Moon and not Earth becauseEarth is covered in land and sea.
No rocks found from meteorites, the Earth, Moon
or Mars have been older than 5000myo.
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Dinosaur
Extinction
Dinosaurs were thought to be dying out anyway but mostaccepted theory is a massive asteroid striking the Gulf ofMexico (65mya).
Impact partly vapourised the ground, wind carried thematerial around the world, and it settled into layer of dust
(contains iridium found in meteorites). Another theory; huge floods of molten basalt rock from
frequent eruptions (India, Siberia especially). Not all flood basalt events have caused a mass extinction
though as happened with the dinosaurs.
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What are we
made of?
Earth made from just 92 different atoms. Observations of sunlight spectrum found the
same 92 atoms only. Heat of stars estimated using colour (white-hot
warmer than red-hot).
Stars are mainly hydrogen which fuses to formhelium (nuclear fusion) making energy. If a starwas just a fire-ball it would use up oxygen quick.
Eventually stars use up hydrogen and start to
die out and give out less and less energy.
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Life of a Star
Nebula
Protostar
Main SequenceStar (the Sun)
Red Giant
White Dwarf Black Dwarf
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Are we
alone?
Parallax; The shift of an object against a more distant background.
Further away the less it shifts. Used to measure distance tostars.
Brightness; Nearer an object (star) the brighter it is.
Light-year; Distance that light travels in a year.
Exoplanets; A planet of any star apart from the Sun. Around 130 at the
moment could they sustain life?
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Formation of the
Universe
Telescopes work better away from sea level (lesslight pollution such as streetlamps).
Used to work out distances between galaxies which
shows that they are moving away from each other.
Big Bang Theory; That the Universe burst into existence from nothing with incredible
heat. Some evidence for this comes from microwaves.