p1 earth + the universe

8/14/2019 P1 Earth + the Universe

1/13

P1 Earth + the

Universe

Revision Notes


2/13

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


3/13

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).


4/13

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.


5/13

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).


6/13

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).


7/13

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.


8/13

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.


9/13

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.


10/13

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.


11/13

Life of a Star

Nebula

Protostar

Main SequenceStar (the Sun)

Red Giant

White Dwarf Black Dwarf


12/13

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?


13/13

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.

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