P1- The Earth in the Universe Revision

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  • Created by: ElishaG
  • Created on: 23-05-16 14:42
What does the solar system consist of?
1)A star (the Sun). 2)Eight planets orbiting the sun in elipses. First 4 called inner planets. 3)Then asteroid belt. 4)Then other 4 planets (outer planets).
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Name three other things that orbit the sun.
1)Dwarf planets.2)Comets. 3)Dust.
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What orbits planets?
Moons, usually much smaller and close to the planet.
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What is the difference between stars and planets?
Stars are huge. very hot and very far away. Give out lots of light. Planets much smaller, just reflect sunlight.
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How was the solar system formed?
1-Over very long period from big dust and gas clouds. 2-One star squeezed slightly (for some reason).3-Gravity took over particles, pulled closer together untill collapsed in on itself.4-Centre of collapse, protostar formed, when temperature hot....
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Solar system formed continued....
...Fusion of hydrogen nuclei to helium starts. 5)Fusion gives off huge amounts of heat and light.6)All elements in cloud with heavier atom than H and He formed in stars by fusion of different nuclei.7-Around sun, planets formed.
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How old is the Solar System?
Around 5000 million years old.
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How old are the oldest rocks on Earth?
4500 million
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What are asteroids?
Fairly small lumps of rubble and rock left over from the formation of the solar system.
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What are comets?
Balls of rock, dust and ice that orbits the sun in elongated ellipses.As a comet approaches sun, ice melts leaving bright tail of gas and debris, hundreds of km long.
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How many stars make up the milky way galaxy?
10 to the power 11
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What is the distance to neighbouring stars?
Millions times greater thank distance between planets.
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How many galaxies are there?
Over a thousand million.
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What is distance in space measured in?
Light years.
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What are light years?
The distance light travels through a vacuum (Like space) in a year.
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How fast does light travel?
300,000 km/s.
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How much bigger is the suns diameter than the Earth's?
100 times.
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How much bigger is the diameter of the milky way than the Sun's?
600 billion times.
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How much bigger is the distance between the Milky Way and the nearest galaxy compared to the sun and its nearest star?
600,000 times further apart.
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How old is the Earth?How old is the Sun?How old is the Universe?
Earth-5000 million years. Sun-5000 million years. Universe-14,000 million years.
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What are two ways of working out how far away a star is?
Parallax angle and Measuring the brightness.
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What is parallax angle?
Take pictures of sky 6 months apart. The apparent movement of a star between the two photos allows you to work out how far away it is.Further away a star is, the less it appears to have moved.
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How can measuring the brightness be used to find out the distance to a star?
Astronomers know amount of radiation certain types of star emit, by seeing how bright they look from Earth, they can tell how far away the stars must be.
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Why did scientists put the Hubble telescope in space?
1)The Earth's atmosphere absorbs a bit of the light from space. 2)Light pollution, e.g. from streetlamps, not seen in space.
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How fast does electromagnetic radiation travel?
Speed of light (300,000 km/s).
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Explain why we see stars and galaxies as they were in the past.
Sun is 150 million km from Earth, takes 8 minutes for radiation to travel so we see sun as it was 8 minutes ago.Nearest star after sun is 4.2 light years away, so would take 4.2 years to reach us. North star see as it was 430 years ago, (Shakespeare)
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What does the wavelength of light do when a galaxy is moving away from us?
Light becomes redder, this is called red shift. The greater the red shift, the faster it's moving away.
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What do we know from the observations of different red shifts?
The more distant the galaxy, the faster it moves away from us.
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What evidence does red shift provide us with?
That the universe is expanding.
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What is the Big Bang theory?
1)Matter compressed into very small space, then exploded and started to expand,still expanding now. 2)Age of Universe estimated from current rate of expnsion, think BB ocurred 14,000 million years.3)Difficult to estimate age, expansion rate slowed.
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Explain the theories for how/if the Universe will end.
1)Depends on speed of expansion and total mass in it.2)These things hard to measure.3)Hard to accurately measure distances.4)Need to accurately observe motions-difficult as far away.5)Tricky to measure mass as some is invisible(dark matter)....
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How Universe will end continued...
6)Amount of dark matter (and what is is)is one of biggest unanswered questions. Amount of dark matter matters.
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Why does the amount of dark matter matter?
All mass attracted together by gravity. More mass, more pull and greater slowing down of expansion.
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What will happen if there's enough mass compared to how fast galaxies are moving?
Universe will stop expanding and start contracting- The Big Crunch.
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What wil happen if there's not enough mass in the universe to stop the expansion?
Could expand forever with universe becoming more and more spread out.
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Describe how rocks provide a record of change in the Earth.
Erosion occurs everywhere, e.g. when cliffs are worn away. But other processes occur to form new rock. Fossils prove rock is constantly forming as they're found in the middle of rocks.Age of Earth can be estimated by age of rocks.
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Explain how rocks are recycled.
1)Particles eroded from existing rock get washed into sea, settle as sediment. Over time, sediments pushed together to form sedimentary rock.2)Can get pushed to surface or descend into heat and pressure. If descend, rock heated and crushed...
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Rocks recycled continued
Sometimes rock melts and then solidifies near Earth's surface.3)When rocks pushed to reach surface, process starts again.
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Why did people think similar fossils werefound in South America and Africa?
Land bridges used to connect the continents together but sunk or were covered by water when the Earth cooled.
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What else puzzled people?
The South American and African coastlines matched well. Sea creature fossils were found on the Alps.
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Explain Wegener's theory...
1)Africa and South America were once joined and then split.2)Evidence-matching layers of rock and fossils in both.3)300 million years ago, one super continent (Pangaea). Broke into small chunks (continent today) and slowly drifting apart.
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Why wasn't Wegener's theory accepted at first?
1)He explained things that couldn't be explained by land bridge theory, like mountain building (when continents smash together).Other scientists hostile.2)Movement of drifting plates not detectable. Wegener thought it was due to tidal waves and ...
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Why Wegener's theory wasn't accepted continued...
Earth's rotation, geologists showed it was impossible. 3)Wegener was a meteorologist not a geologist.
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What proved Wegener's theory?
1)1950's scientists investigated mid-Atlantic ridge(whole length of Atlantic).2)Found magma rises through sea floor, solidifies and forms underwater mountains, roughly symmetrical on each side.Evidence suggested sea floor was spreading few cm a year.
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What proved Wegener's theory continued...
3)As liquid magma erupts, iron particles in rock align themselves with Earth's magnetic field.Every half million years, magnetic field swaps direction. Rock on each side of ridge has symmetrical bands of alternate magnetic polarity.
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What are the four different layers of the Earth?
1)Crust. 2)Mantle. 3)solid outer core. 4)liquid inner core.
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What are the two types of crust?
Continental crust and oceanic crust.
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What's the mantle?
It has all of the properties of a solid but it flows very slowly.
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What is at the centre of he Earth?
We think it's mainly iron and nickel.
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What causes tectonic plates to drift?
Convection currents in the mantle, caused by heat in the core.
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How much do the tectonic plates move per year?
A few cm relative to each other.
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What causes earthquakes?Where are they most likely to occur?
Sudden movement of the plates. Happen more often near edges of plates.
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How are volcanoes formed?Where are they formed?
Magma is produced where two plates meet, can rise up, forming volcanoes. Formed where plates meet.
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How are mountains formed?
When plates crash into each other.
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What do earthquakes cause?
Different types of seismic waves: wave motions(shock waves) that travel on the surface and inside Earth
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How are seismic waves measured?
Using seismographs.
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What do seismologists measure?
The time it takes for shock waves to reach each seismograph and which seismographs don't receive any shock waves.
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What are the two types of wave?
P-waves and S-waves.
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Describe P-waves.
Travel through solids and liquids. Faster than S-waves. P-waves are Longitudinal.
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Describe S-waves..
S-eaves only travel through Solids. They are Slower than P-waves. S-waves ate tranSverSe.
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When are seismic waves reflected?
When they reach a boundary between different layers of the Earth.
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When are seismic waves refracted?
Waves change speed a properties of mantle and core change. Change in speed causes waves to change direction (refraction).
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What happens when a waves changes speed gradually?
The path is curved.
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What happens when properties change suddenly?
Wave speed changes abruptly and path has a kink.
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How do waves show the structure of the Earth?
1)Halfway through Earth, P-waves abruptly change direction, shows property change from mantel to core.2)S-waves not detected in core's shadow, so outer core is liquid.3)P-waves travel faster in middle of core,suggests solid inner core.
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What are all waves?
Disturbances caused by a vibrating source.
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What do waves do?
Carry and transfer energy in the direction that they travel.
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What is amplitude?
The distance from rest position to crest or trough. Bigger amplitude, more energy.
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What is wavelength?
Crest to Crest or Trough to Trough.
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What is frequency?
The number of complete waves passing a certain point per second OR the number of waves produced by a source per second.
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What is frequency measured in?
Hertz(Hz) 1hz = 1 wave per second.
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What are transverse waves?
IN transverse waves, vibrations are 90 degrees to the direction of travel of the wave.
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What are longitudinal waves?
In longitudinal waves the vibrations are along the same direction as the wave is travelling.
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What are the two formulas for speed?
Speed= distance/time Speed(m per s)= Frequency (Hz) x Wavelength(m)
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