the earth in the universe Flashcards
what are asteroids?
irregular lumps of rock
what are comets?
small objects made of rock and ice
what is the order of the planets from the heaviest?
jupiter, saturn, uranus, neptune, earth, venus, mars, mercury
what are dwarf planets?
small spherical lumps of rock
what is the milky way?
one of thousands of millions of galaxies which make up the universe
what are light years?
distance that light travels in a year
what speed does light travel in?
through a vacuum at speed of 300 000 km/s
where does the evidence from distant stars and galaxies come from?
radiation
whats the relationship between the distance of the star and its’ relative brightness?
the further away a star, the smaller the relative brightness
if know distance to 1 star, diff in relative brightness can be used to calculate the other
what are the uncertainties of measuring the distance to stars in this way?
estimating distance to 1 star
difficult to make precise observations e.g dust, rain, light pollution
what is parallax?
as earth orbits sun, nearby stars move against fixed background of distant stars
what is nuclear fusion?
hydrogen nuclei jammed so they combine in pairs to form helium, releasing energy
how do galaxies appear to us?
to be moving away, increasing wavelength of light we receive from them
what is redshift?
increase of wavelength from a galaxy moving away
what is the relationship between redshift and distant galaxies?
amount of redshift increases with distance from earth
further away from earth a galaxy is, faster its moving away
when was the universe created?
14 000 million years ago from a single point
when was the sun created?
5000 million years ago
when was earth created?
4500 million years ago
what evidence supports the big bang theory?
detection of cosmic background radiation
what does the fate of the universe depend on?
how it continues to expand
if enough mass in universe, gravity will slow down expansion and make it collapse again
why is the fate of the universe hard to predict?
can only measure mass of parts of universe which emits radiation
speed and distance of galaxies = diff to measure bc radiation travels a long way to get to us
what was wegeners theory?
single land mass split into several continents which drifted
what evidence did wegener base his theory on?
continents fit together so well
why didnt geologists accept wegeners theory?
had simpler theories
not a trained geologist
no one could measure the movement of continents
what is the structure of the earth?
core = liquid iron
semi liquid rock in mantle floats on core
outer core = layer of liquid nickel and iron, 1250 km thick
thin layer of solid rock in crust floats on mantle
what are the two types of seismic waves that are generated when tectonic plates move?
p waves
s waves
what are p waves?
move through liquid core and solid crust
longitudinal
what are s waves?
move through only slowly through solid crust
transverse
what is a wave?
transfers energy from a vibrating source
what is an amplitude?
maximum height of the disturbance
what is the wavelength?
distance from one maximum disturbance to the other
what is an oscilloscope?
machine that displays waves on the screen
grid on screen lets you compare wavelength and amplitude of waves:
- sound is louder if larger amplitude
- sound is higher pitched if shorter wavelength
what is the wave equation?
wave speed (m/s) = frequency (Hz) x wavelength (m)
what are geohazards?
natural hazards
precautionary measures:
- buildings withstand tremors
- refuse planning permission in areas prone to flooding
what is a supernova?
heavy stars in this way
massive explosion where diff elements are made (heavier than iron)
what are tectonic plates?
meet at plate boundary forming mountains, earthquakes and volcanoes
how are volcanoes formed?
liquid magma forces through cracks where tectonic plates are moving apart
how are fold mountains formed?
2 tectonic plates meet head on
explain sea floor spreading?
convection currents cause magma to rise , currents move solid part of mantle and tectonic plates
when plates moving apart, magma reaches surface and hardens forming oceanic crust and pushing floor out
new crust forming at the crest of an oceanic ridge and old rock pushed out
explain the magnetic field?
magnetic field changes polarity producing rock stripes of alternating polarity occurring at constructive plate boundaries
whats subduction?
when oceanic and continental plates collide, the denser oceanic plate is forced under the continental plate
occurs at destructive plate boundaries
how do earthquakes occur?
plates slide past each other or collide
pressure builds up
stored energy is released and waves of energy spread from the epicentre
why are plate movements crucial in the rock cycle?
old rock destroyed by subduction
igneous rock is formed when magma reaches surface
plate collisions produce high temp and pressure causing rock to fold
sedimentary rock becomes metamorphic rock
