20/09/2018 The Earth and Beyond

There are nine planets in our solar system: 20/09/2018 Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto My Very Easy Method Just Speeds Up Naming Planets

The Earth orbits the sun… …every year (365 1/4 days) 20/09/2018 …every year (365 1/4 days) Ellipse

We see planets and the moon because they reflect sunlight: 20/09/2018 The sun is different – it produces its own light.

The Earth is kept in orbit by 2 things… 20/09/2018 The Earth is kept in orbit by 2 things… Gravity …and by the fact that it is moving at a high velocity

The Earth spins on an axis… 20/09/2018 The Earth spins on an axis… Because of this spin the sun and stars appear to “move” across the sky…

Note that this force goes both ways – the Earth is attracted to us. Gravity 20/09/2018 Gravity is an attractive force that affects anything with mass: Note that this force goes both ways – the Earth is attracted to us.

Gravity on different planets: 20/09/2018 Gravity on different planets: Jupiter – gravitational field strength = 25N/Kg Earth – gravitational field strength = 9.8N/Kg

More information on gravity 20/09/2018 The amount of gravity attracting an object decreases the further out the object is… F If you double the distance the gravitational force divides by 4… F/4 If you triple the distance the force divides by 9… F/9

How much of the moon we see depends on where the moon is in its orbit: 20/09/2018 Appearance:

20/09/2018 Appearance:

20/09/2018 Appearance:

Comets 20/09/2018 Comets are balls of dust and frozen gas. They have very elliptical orbits: As the comet approaches the sun gases evaporate from it, forming a “tail”. This tail always faces AWAY from the sun.

Artificial Satellites 20/09/2018 Geostationary orbits: Low polar orbits:

Artificial Satellites 20/09/2018 Artificial satellites have been around for 50 years and have 3 main uses: 1) Observation (e.g. Hubble Space Telescope) – these are in orbit high above the Earth and can observe the universe without interference by the ____________ 2) Communications (e.g. ___, phone, car “SatNav” systems) – these satellites are in “geostationary” orbits. This means that the satellite always stays above ____ ____ point on the Earth and takes a ______ to complete an orbit 3) Monitoring (e.g. weather, spy satellites) – these satellites have a “___ _____” orbit and may scan around the Earth several times a day Words – the same, atmosphere, low polar, TV, day

Solar systems, galaxies and the Universe 20/09/2018 (Basically, everything in the universe orbits around something else) OUR SUN is one of millions of stars that orbit the centre of… THE MILKY WAY, which is one of a billion galaxies that orbit AND move away from the centre of… THE UNIVERSE

Quiz.. What is the sixth planet in the solar system? 20/09/2018 What is the sixth planet in the solar system? What is the biggest planet in the solar system? Name 2 differences between stars and planets How long does the Earth take to orbit the sun? What 2 things keeps the Earth in orbit? Why does Mars take longer to orbit the sun than Earth? How long does the moon take to orbit the Earth? Would the acceleration due to gravity on Mars be bigger or smaller than on the Earth and why? Which hemisphere is Britain in?

Quiz.. What is the name of the line that divides the two hemispheres? 20/09/2018 What is the name of the line that divides the two hemispheres? How long does the Earth take to rotate? Where does the sun rise and set? If you double the distance between two objects what happens to the force of gravity between them? What shape describes the shape of a comet’s orbit? What is a comet made up of? Where does a comet’s tail point and why? What keeps stars in orbit around the centre of a galaxy?

Searching for ET 20/09/2018 In any scientific enquiry you have to OBTAIN some evidence and then ANALYSE it (just like your coursework). Consider searching for extra-terrestrial life on Mars: OBTAINING EVIDENCE Fly to Mars yourself (takes ages) Use robots to bring back samples (not very reliable) Use robots to take pictures and send them back (also not very reliable) ANALYSING EVIDENCE Use microscopes to search for fossilised remains inside the samples Place the sample in a container and monitor changes in the environment due to living organisms being present in the sample

Evidence about the origins of the universe… 20/09/2018 Evidence about the origins of the universe…

Source of light “Spectra” 20/09/2018 Source of light “Spectra”

If you pass the light through a gas something different is seen… 20/09/2018 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”.

Before helium helium After 20/09/2018 If the light source is moving away the absorption spectra look a little different… helium Before helium After

20/09/2018 The absorption lines have all been “shifted” towards the longer wavelength end (red end)… Before This is called red shift. The faster the light source moves the further its light will be “shifted” After A similar effect happens with sound – this is called “The Doppler Effect” Hear Doppler Effect

This is the BIG BANG theory 20/09/2018 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

Words to use – faster, away, big bang, billion, wavelength, further Red shift summary 20/09/2018 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 15 _____ years ago. This is the ____ ________ Theory. Words to use – faster, away, big bang, billion, wavelength, further

20/09/2018 The Life Cycle of a Star

Stage 1: Nebulae A nebulae is a collection of dust, gas and rock. 20/09/2018 A nebulae is a collection of dust, gas and rock. Some examples of nebulae…

20/09/2018 (No need to know these names) Dark nebula

20/09/2018 (No need to know these names) Emission nebula

20/09/2018 (No need to know these names) Planetary nebula

20/09/2018 (No need to know these names) Reflection nebula

Stage 2: Protostar 20/09/2018 Gravity will slowly pull these particles together… As they move inwards their gravitational potential energy is converted into heat and a PROTOSTAR is formed The force of gravity makes the dust particles come spiralling in together. As they do so their gravitational potential energy is converted into heat energy and the temperature rises…

Words – heavier, balanced, hydrogen, nuclear, temperatures Stage 3: Main Sequence 20/09/2018 Our sun is an example of a main sequence star – it’s in the middle of a 10 billion year life span In a main sequence star the forces of attraction pulling the particles inwards are _________ by forces acting outwards due to the huge __________ inside the star. 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. Words – heavier, balanced, hydrogen, nuclear, temperatures Eventually the temperature rises enough for the hydrogen gas to undergo nuclear fusion. A massive amount of heat and light are given out and the star is stable for around 10,000 million years.

Stage 4: Red Giant 20/09/2018 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 Eventually the hydrogen begins to run out and the star swells into a red giant. (At this point our sun will suck in Earth and the planets around it) If the star is big (at least 4 times the size of our sun) it will become a RED SUPERGIANT

Stage 5: The Death 20/09/2018 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 For small stars the star will shrink into a WHITE DWARF and then it cools and fades to a BLACK DWARF (like a dying fire) White dwarf Black dwarf

This explosion is called a SUPERNOVA 2) If the star was a RED SUPERGIANT it will shrink and then EXPLODE, releasing massive amounts of energy, dust and gas. 20/09/2018 Before After This explosion is called a SUPERNOVA When a big star runs out of fuel it would collapse and blow off its outer layer in an enormous explosion called a SUPERNOVA (click to show picture)

If the star is big enough it could become a BLACK HOLE. 20/09/2018 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. 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 will become a BLACK HOLE. (The picture shows a black hole after forming in the middle of other stars)

Stage 6: Second generation stars 20/09/2018 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 the products of a previous star that have been thrown out by a ________. 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 The dust and gas thrown off by the supernova will form SECOND GENERATION stars (like our sun) and a new solar system