The Universe
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?- Created by: Hannah
- Created on: 04-05-15 14:43
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- The Universe
- The Structure
- The Solar System
- Part of a GALAXY called The Milky Way
- Spiral galaxy
- There are billions of stars in a galaxy and billions of galaxies in the Universe
- Sun is in the centre, holding everything else in orbit.
- Around = Planets, Moons, Asteroids, Comets etc.
- Part of a GALAXY called The Milky Way
- Life Cycle of a Star
- Slightly
denser areas of the universe
have a slightly higher gravitational pull.
- This pulls in material, making it denser and giving it a greater gravitational pull, so it pulls in more material.
- As it collapses, temp increases as PE --> KE, star ignites and is now a PROTO STAR
- Once hot enough, FUSION can occur, burning hydrogen to helium
- This creates radiation pressure, when radiation pressure = gravitational force the star is stable
- Once there is no hydrogen left to burn, star collapses in and reignites burning helium etc., Red Giant= much larger and cooler
- Sheds outer layers of gas, eventually contracting to form a white dwarf
- Once there is no hydrogen left to burn, star collapses in and reignites burning helium etc., Red Giant= much larger and cooler
- This creates radiation pressure, when radiation pressure = gravitational force the star is stable
- Once hot enough, FUSION can occur, burning hydrogen to helium
- As it collapses, temp increases as PE --> KE, star ignites and is now a PROTO STAR
- This pulls in material, making it denser and giving it a greater gravitational pull, so it pulls in more material.
- Slightly
denser areas of the universe
have a slightly higher gravitational pull.
- The Scale of the Universe
- One astronomical unit is the distance from the earth to the sun
- A light year is the distance travelled by light in a year. Using distance = speed x time
- Parsec Distance of object who's parallax is 2 seconds
- Oblers' Paradox
- The sky is dark at night, meaning there is a FINITE number of stars.
- 1)The universe is not infinite/ 2) stars are not uniformly distributed/ 3) it is static. 1) generally accepted
- The sky is dark at night, meaning there is a FINITE number of stars.
- Cosmological Principal
- On the large scale the Universe is uniform, no where is special, it is isotopic and homogenous
- The Solar System
- Evolution of the Universe
- The Big Bang
- Approx 13 Billion year ago all of the matter and energy in today's universe was compressed to a singularity, from which it has expanded
- Cosmic Background Radiation
- We receive background radiation in the microwave region in all directions
- Fate of the Universe
- Open Universe
- Density < Critical, continues to expand forever
- Closed Universe
- Density > Critical, eventually gravity causes collapse and BIG CRUNCH
- Flat Universe
- When density = Critical density, expanding more and more slowly, but never going into reverse
- Open Universe
- Critical Denisity
- Corresponds to Flat Universe, given by
- The Big Bang
- The expanding Universe
- Red Shift
- A version of the Doppler Effect, if a galaxy is moving away, its light is shifted towards the red spectrum.
- Change in wavelength / original = speed of recession / speed of light
- "Blue Shift" occurs when something is travelling towards us.
- Hubble's results
- Hubble plotted a graph of galaxies speed of recession, against distance from Earth
- Found that the relationship was directly proportional.
- Hubble Constant =Gradient( Ho)
- Hubble's Law Speed of recession ? distance. V=H x
- Hubble plotted a graph of galaxies speed of recession, against distance from Earth
- The age of the Universe
- We can deduce the age of the Universe by using the Hubble constant.
- Age= 1/Ho
- Ho = 71 km/s/Mpc 1Mpc= 3x10^22 Ho=71000/ 3x10^22 1/Ho=age APPROX 13.4 Billion years old
- Untitled
- Hubble's law and Obler's paradox
- Hubble's Law shows that the universe is EXPANDING
- Hubble showed distant galaxies are moving very fast. Very distant galaxies have redshifts so large their light is shifted out of the visible spectrum. A reason why night is DARK
- Red Shift
- The Structure
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