21/11/ /11/2017 Space Physics AQA Physics topic 8

Transcription

1 Space Physics AQA Physics topic 8

2 8.1 Solar System, Orbits and Satellites

3 The eight planets of our Solar System Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune As well as the eight planets, the solar system is also made up of asteroids, dwarf planets, comets and moons

4 Asteroids An asteroid belt lies between Mars and Jupiter. But what is an asteroid?

5 Comets Comets are balls of dust and frozen gas. They have very elliptical orbits: Notice how the tail always points away from the sun!

6 The Solar System summarised What makes up our solar system? Complete the following mind map with what you now about each object: The solar system

7 Solar systems, galaxies and the Universe Our planet (around 13,000km diameter) is pretty small compared to... OUR SUN (100 times wider), which is small compared to THE UNIVERSE, which contains billions of galaxies. THE MILKY WAY, which contains at least 200 billion stars, which is small compared to

8 Nuclear Fusion vs Nuclear Fission Nuclear fission happens in power plants and nuclear bombs it s basically splitting a nucleus. Nuclear fusion happens in stars it s basically fusing nucleii together

9 The Life Cycle of a Star

10 Stage 1: Nebulae A nebulae is a collection of dust, gas and rock. Some examples of nebulae

11 Dark nebula

12 Emission nebula

13 Reflection nebula

14 Planetary nebula (This nebula is smaller and will only form a planet)

15 Stage 2: Protostar Gravity will slowly pull these particles together As they move inwards their gravitational potential energy is converted into heat and a PROTOSTAR is formed

16 Stage 3: Main Sequence In a main sequence star the forces of attraction pulling the particles inwards are by expansion forces due to nuclear reactions and the high temperature. Stars are basically reactors that use as a fuel. During its main sequence a star will release energy by converting hydrogen and helium (light elements) into elements and this is why the universe now contains a number of heavier elements. Our sun is an example of a main sequence star it s in the middle of a 10 billion year life span Words heavier, balanced, hydrogen, nuclear, fusion

17 Nuclear Fusion in stars Proton Neutron Nuclear fusion happens in stars and leads to the formation of new elements. It s not possible to use it in power stations yet as it needs temperatures of around 10,000,000 O C and seriously high pressure.

18 Stage 4: Red Giant Eventually the hydrogen and helium will run out. When this happens the star will become colder and redder and start to swell If the star is relatively small (like our sun) the star will become a RED GIANT If the star is big (at least 4 times the size of our sun) it will become a RED SUPERGIANT

19 Stage 5: The Death What happens at this point depends on the size of the star 1) For SMALL stars the red giant will collapse under its own gravity and form a very dense white dwarf: Red giant White dwarf Black dwarf

20 Stage 5: The Death 2) If the star was a RED SUPERGIANT it will shrink and then EXPLODE, releasing massive amounts of energy, dust and gas. This explosion is called a SUPERNOVA Before After

21 Stage 5: The Death The dust and gas on the outside of the supernova are thrown away by the explosion and the remaining core turns into a NEUTRON STAR. If the star is big enough it could become a BLACK HOLE instead.

22 Stage 6: Second generation stars The dust and gas thrown out by a supernova can be used to form a new star Our sun is believed to be a star this is because it contains some elements along with hydrogen and. These heavier elements would have been produced by a and thrown out when the star exploded. These heavier elements are also found on planets, indicating that they might have been made from remains of previous as well. Words helium, heavier, second generation, stars, supernova

23 The Life Cycle of a Star summary SMALL stars Protostar Main sequence BIG stars Red giant Red super giant White dwarf Supernova Black dwarf Neutron star Black hole Basically, it all depends on the size of the star!

24 The Earth s Orbit Gravity keeps us in orbit around the sun. How long does this orbit take? Ellipse

25 Circular Motion recap 1) Is this car travelling at constant speed? 2) Is this car travelling at constant velocity?

26 The Moon s Orbit Gravity also keeps the moon (a natural satellite) in orbit around us. How long does this take? Does the moon travel at constant speed? Does it travel at constant velocity?

27 Satellite orbits Gravity also keeps artificial satellites in orbit around us. Q. What would have to happen to the satellite s speed if it moved closer to the Earth? A. As the orbital radius INCREASES the speed of the satellite will DECREASE.

28 8.2 Red Shift

29 How did the universe begin? The Big Bang Theory suggests that the universe began from a very small region that was very hot and dense, and then

30 How did the universe begin?

31 Evidence for the Big Bang Theory Source of light Spectra

32 If you pass the light through a gas something different is seen helium Some wavelengths of light are absorbed by the gas an absorption spectrum.

33 If the light source is moving away the absorption spectra look a little different Before helium After

34 The absorption lines have all been shifted towards the longer wavelength end (red end) This is called red shift. The faster the light source moves the further its light will be shifted Before After A similar effect happens with sound this is called The Doppler Effect

35 Red Shift simplified Basically, if I walk towards you I ll look slightly more blue. Then, if I walk away from you, I ll look slightly more red!! Let s try it

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38 Light from different stars and from the edge of the universe also shows this red-shift. This suggests that everything in the universe is moving away from a single point. This is the BIG BANG theory

39 Red shift summary Light from other galaxies has a longer than expected. This shows that these galaxies are moving from us very quickly. This effect is seen to a greater extent in galaxies that are away from us. This indicates that the further away the galaxy is, the it is moving. This evidence seems to suggest that everything in the universe is moving away from a single point, and that this process started around 14 years ago. This is the Theory. Observations of from 1998 onwards have suggested that distant galaxies are receding even faster. Words to use faster, away, big bang, billion, wavelength, further, supernovae

40 Dark Mass and Dark Energy So, does this mean that we now know everything about the universe? No Mr President! There is still loads of stuff we don t know about the universe, such as dark mass and dark energy.