P1-The Earth In The Universe Flashcards
Name the inner planets
Mercury
Venus
Earth
Mars
Name the outer planets
Jupiter
Saturn
Uranus
Neptune
What is the difference between the outer planets and the inner planets?
The inner planets are rocky and the outer planets are gaseous
What separates the inner and outer planets?
The asteroid belt
What else orbits the sun?
Dwarf planets Comets Asteroids Dust Moons
What are the differences between stars and planets?
Stars: Larger Hot Further away Give out light
Planets:
Smaller
Reflect sunlight, don’t emit it
Closer than any other star other than the sun
How old is the solar system?
5 thousand million years old
How was the solar system formed?
Big clouds of dust and gas started to get compressed and squeezed
Once the particles where close to each other gravity pulled them in closer until the cloud collapsed in on itself
At the centre of the collapse the particles formed a protostar
Increased temperature caused fusion
Fusion gives out lots of heat and light so the sun was born
Chemical elements heavier than hydrogen and helium where formed by the fusion of different nuclei
The clouds around the sun containing the elements clumped together and formed planets
Oldest rocks on earth where meteorites
What are the oldest rocks on earth?
Meteorites
How to we know how old the solar system is?
The fist rocks on earth are 4500 million years old
What are asteroids and comets made out of?
Things left over from the formation of the Big Bang
What are asteroids?
Small lumps of rubble and rock
What are comets?
Balls of rock ice and dust which orbit the sun in elongated ellipses
As the comet approaches the sun it’s ice melts leaving a bright trail of gas and debris which can be millions of kilometres long
What orbit do comets take?
Elongated ellipses
How many stars are in the Milky Way?
Thousands of millions
10*11
What shape is the Milky Way?
Has spiral arms
How much greater is the distance between neighbouring stars in a galaxy than the distance between planets in the solar system?
Millions of times greater
How many galaxies are in the universe?
Thousand million
What is a light year the measure of?
The distance light travels through a vacuum In one year
What is the speed of light?
300,000 km/s
Order from smallest to largest the:
Diameter of the Milky Way
Diameter of the earth
Diameter of earths orbit
Distance from the Milky Way to the nearest galaxy
Distance from the sun to the nearest star
Diameter of the sun
Diameter of the solar system
Diameter of earth Diameter of sun Diameter of earths orbit Diameter of solar system Distance of sun to nearest star Diameter of the Milky Way Distance of milky way to nearest Galaxy
What tells us a lot about a star?
Electromagnetic radiation
How can we work out how far away a nearby star is?
Parallax
Pictures of the sky are taken six months apart
The apparent movement of the star between the two photos lets you work out how far away it is
Stars further away move less
Measure brightness
What is parallax?
The apparent shift of an object when looked at from different places
What is a disadvantage with using brightness to measure the distance to a star?
A star that looks very bright form earth could be
Close to earth but not bright
A long way and very bright
Name all of the planets in order from closest to the sun to furthest away
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
How does the atmosphere and light pollution cause problems?
The atmosphere can absorb light coming from space
Light pollution makes it hard to see dim objects
How long does it take for radiation from the sun to reach us and what does this mean?
8 minutes
This means we see the sun as it was 8 minutes ago
What do we know about galaxies based on out observations of red shift?
The more distant the Galaxy, the faster it moves away from us
What happens when a Galaxy moves away from earth?
The wavelength of light becomes redder
This is red shift
What is red shift?
When the wavelength of light gets redder due to a Galaxy moving away from us
What evidence is there that the universe is expanding
Red shift
What is the Big Bang theory?
All matter in the universe was compressed into a very small space and then exploded and started expanding
It is estimated to have happened 14 billion years ago based on rate of expansion
This is difficult to estimate because it’s hard to tell how much the rate has slowed down since the Big Bang
Why is it difficult to estimate how long ago the Big Bang occurred?
Because it is difficult to tell how much the rate of expansion has slowed
What does the universes fate depend on?
How fast it is expanding and the total mass in it
Why is it difficult to measure the total mass of the universe?
Most of it is invisible dark matter
It can only be detected by how it effects things we see
Why is it difficult to calculate how fast the universe is expanding?
Because there is large distances so it’s hard to accurately measure
What are the two ways the universe could end?
If there is enough mass compared to how fast the galaxies are moving the universe will stop expanding and begin contracting.
If there is not enough mass in the universe then it could expand forever
What evidence to fossils provide?
They provide evidence that rock is constantly forming
Rock built up around fossils
What can be estimated from rocks?
The age of the earth
Oldest rocks found are 4billion years old
Describe the rock cycle
- Particles eroded from existing rock (eg by water flowing over them) get washed into the sea and settle by sediment. Overtime the sediments crush together to form sedimentary rocks
- Sedimentary rocks can descend into the heat and pressure inside the earth or get pushed to the surface.
- If they descend then the structure of the
rock changes as it gets heated and crushed. Some rock melts but solidifies if it cools near the earths surface. - Rocks that are pushed up restart the cycle
What evidence is there that the rock cycle occurs?
The rock as been pushed, squeezed so hard it has folded.
What was wegeners theory?
He hypothesised that South Africa and America had previously been one continent that had split.
This was continental drift
300million years ago there was one supercontinent called Pangea
Pangea broke into smaller continents
What evidence was there for Wegeners theory?
There where matching layers in the rocks on different continents and similar fossils in South America and South Africa
Why wasn’t wegeners theory accepted?
Wegener wasn’t a geologist, he was a meteorologist
Other scientists believed land bridge theory was correct
The continental drift wasn’t detectable
He couldn’t explain how the drifting occurred
How was continental drift proved?
In 1950s the mid Atlantic ridge was discovered
Evidence that magma rises up through the sea floor solidifies and forms underwater mountains that are roughly symmetrical either side of the ridge.
This suggest sea floor spreading a few cm w year
Magnetic orientation of the rocks proved it
Iron particles in the rocks align themselves with the earths magnetic field cools and sets in position
Every half a million years, the earths polarity changes direction so the rock on either side of the ridge has bands of alternating magnetic polarity symmetrical about the ridge.
How much does the sea floor spread per year?
Few cm per year
What is the structure of the earth?
Thin crust Continental crust (forming the land) Oceanic crust (under oceans)
Mantle
All of the properties of a solid but it flows very slowly
Heat from the core and from radioactive decay causes the mantle to flow in convection currents
Core
Mainly iron and nickel
What are tectonic plates?
Large pieces that float on the mantle
What causes tectonic plates to drift?
Convection currents in the mantle
Where do earthquakes mostly happen?
On the edge of plates
How are mountains made?
When plates crash into each other
What are the two different types of waves?
P waves
S waves
What is a p wave and what does it ravel through?
Longitudinal
Solids and liquids
Faster than S waves
What are S waves?
Travel through solids only
Slower than p waves
Transverse
What happens when there is a sudden change in properties?
Reflected
Change speed therefore direction (refraction)
Curved path if direction changes slowly
Sudden change causes a kink
What can p waves and S waves tell us about the structure of the earth?
There is a sudden change of properties as you go from the mantle to the core due to p waves changing direction quickly
S waves are not detected in the cores shadow so the outer core is liquid
P waves travel faster in the middle of the core which suggests there is a solid inner core
S waves travel through the mantle so it is solid
What are waves?
Disturbances caused by a vibrating source
What to they carry?
They carry and transfer energy in the direction that the wave travels.
Not matter
What is amplitude?
The distance from the rest position to the crest or trough
What does amplitude affect?
The bigger the amplitude, the more energy a wave has.
What is wavelength?
The length of the full cycle of the wave
Crest to crest
What is frequency?
The number of waves produced each second
What is frequency measured in?
Hertz (Hz)
How do you work out the distance?
Distance= speed X time
Describe a transverse wave
Vibrations are 90 degrees to the direction of travel
Vibrations from side to side
Give an example of a transverse wave
Em waves
Light
S waves
What is a longitudinal wave?
Vibrations are in the same direction that the wave is travelling
Give an example of a longitudal wave
Sound
Ultrasound
P waves
What is the equation for wave speed?
Speed= frequencyX wavelength
