Zusammenfassung der Ressource
P1
- The solar system
- Centre= Sun
- Eight planets= MVEMJSUN
- Asteroids= irregular lumps or rock
- Comets= small objects of rock and ice (have elongated orbits around the sun.
- Dwarf planets= spherical lumps of rock
- The universe
- We can only see stars as they were in the past
- One light year= 9.5 million million km
- Light travels through a
vacuum at 300000 km/s
- Distance to stars
- Brightness
- Same real brightness doesn't
= same relative brightness
- Further away= smaller relative brightness
- Negatives
- Need to know the distance of one the stars
- Only works if have same real brightness
- Dust, rain, clouds, light pollution
- Parallax
- As earth orbits close stars move
slightly against fixed background
- However, can only be
used of nearby stars
- Expanding universe
- Redshift
- Redshift is the light
coming from distant
galaxies
- As galaxies move away, the wavelength increases
- Most galaxies appear to be
moving away from us
- further away from earth a galaxy is, thefaster it is moving away from us
- Fusion of elements in stars
- Nuclear fusion= only at high densities and temp
- hydrogen nuclei hit
each other so
hard= helium= lots
of energy= nuclear
fusion
- This is how all chemical
elements with atoms heavier
than helium were made
- These elements spread through space when stars explode
- Stars end their lives as a supernova
- Massive explosion
- Where all the different chemical elements are made
- The changing earth
- breaks in earths crust= new volcanoes& mountains
- Sediments crushed together= sedimentary rock (formed
in seas)
- Collisions between different
parts of the crust= mountains
- Rocks provide evidence
for this
- P1
- The big bang
- detection of cosmic background radiation= evidence
- Sun= 5000 million years ago
- Earth= 4500 million years ago
- Universe expanded rapidly from single point 14000 million years ago
- Continental drift
- Alfred Wegener 1915
- Millions of
year ago= one
land mass
- Then it split into
continents which
drifted apart
- Continents move
because they sit
on mantle
- The rocks move slowly by convection currents
- Based on the way the all fit
- And that similar fossils and rocks were found of continents now
separated by oceans
- Oceanic ridges
- Form when sea spreads and liquid rock fills gap
- This rock is magnetised by earths field
- Each time earths field reverses, it is shown in
the rock
- The seafloor increases by cm's/year=
seafloor spreading
- Tectonic plates
- Volcanic mountains= one tectonic plate forced under another
- Earths crust has solid tectonic plates
- Meet at plate boundaries
- Fold mountains= when 2 tectonic plates meet head on
- Earthquakes form= when they slide past each other
- Seismic waves
- S-waves= move slowly through solid
- Can use these to work out the structure of the earth
- Formed when two plates move suddenly
- P-waves= move quickly through solids and liquids
- seismometers record them
- Structure of the earth
- Mantle= solid rock
- Outer core= liquid nickel and iron
- Inner core= solid nickel and iron
- Mantle= semi-liquid rock
- Waves
- Transfers energy
away from a vibrating
sorce
- Wavelength= distance between each peak
- Wave
speed= FxWL
- Higher the frequency
the shorter the wave
length
- Frequency= Number
of vibrations in one
second
- Amplitude= maximum
height of the wave
- Unit of
frequency is
hertz (Hz)