1. The Earth and Beyond

2. There are nine planets in our solar system:
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto

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

4. The Earth orbits the sun every…
…year (365 1/4 days)

5. This orbit is actually a “slightly squashed” circle (ellipse)

6. The Earth is kept in orbit by the force of…
Gravity
…and by the fact that is is moving at a high velocity

7. Gravity also keeps the moon in orbit around the Earth
Gravity also keeps the moon in orbit around the Earth. The moon orbits the Earth every…
…month (28 days)

8. Gravity is ________ if the planet has more mass:
Jupiter
Earth

9. More information on gravity
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

10. How much of the moon we see depends on where the moon is in its orbit:
Appearance:

11. Appearance:

12. Appearance:

13. The Earth is divided up into the northern hemisphere and the southern hemisphere:
Equator

14. The Earth is tilted on an axis
North pole
South pole

15. The Earth spins on its axis every ___ (__ hours)

16. While the Earth is spinning the side that faces the sun is in ________

17. Because of this spin the sun rises in the ______ and sets in the ______

18. The tilt of the Earth on its axis is also responsible for the seasons:
What date is it here?
What date is it here?
June 21st
December 21st

19. The sun appears lower in the _______ than it does in the ______:
Summer
Winter
Longer shadows in winter

20. Two things happen because of this tilt:
The days are longer during the summer
The weather is warmer during the summer (due to the hemisphere being closer to the Sun)

21. Comets
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

22. Satellites
A satellite is anything that ________ something else. The Earth has a natural satellite – this is the ________. The Earth is also a satellite as it orbits the ______. As well as the moon, the Earth has hundreds of other satellites orbiting around it.
All satellites need two things in order to stay in orbit:
A force of gravity
Moving at a fast speed

23. Satellites have three 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. TV, phone, car “SatNav” systems) – these satellites are in “geostationary” orbits. This means that the satellite always stays above ____ ____ point on the Earth and takes __ hours to complete an orbit
3) Monitoring (e.g. weather, spy satellites) – these satellites have a “low polar” orbit and may scan around the Earth several times a day

24. Solar systems, galaxies and the Universe
(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

25. Quiz.. 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 force keeps the Earth from flying away from the sun?
Where does this force point towards when it acts on the 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?
Which hemisphere is Britain in?

26. Quiz.. 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?
What does the tilt of the Earth’s axis cause?
What is the date when the northern hemisphere is tilted towards the sun as far as possible?
How would you describe the shape of a comet’s orbit?
What is a comet made up of?
What point do different galaxies orbit around and move away from?
What keeps these galaxies in their orbits?

27. Searching for ET
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

28. Evidence about the origins of the universe…

29. Source of light
“Spectra”

30. If you pass the light through a gas something different is seen…
helium
Some wavelengths of light are absorbed by the gas.

31. These patterns are called absorption spectra…
…because they show which wavelengths of light are absorbed by the gas (this is how we know the sun is made of helium).

32. If the light starts to move away…

36. Before
helium
After
The results look a little different…

37. 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”

38. This is the BIG BANG theory
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. Words to use – faster, away, big bang, billion, wavelength, further
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 15 _____ years ago. The is the ____ ________ Theory.
Words to use – faster, away, big bang, billion, wavelength, further

40. The Life Cycle of a Star

41. Stage 1: NEBULAE A nebulae is a collection of dust, gas and rock.
Some examples of nebulae…
A NEBULA is a collection of gas, dust and ice.

42. (No need to know these names)
Dark nebula

43. (No need to know these names)
Emission nebula

44. (No need to know these names)
Planetary nebula

45. (No need to know these names)
Reflection nebula

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

47. Stage 3: MAIN SEQUENCE STAR
In a main sequence star the forces of attraction pulling the particles inwards are BALANCED by forces acting outwards due to the huge temperatures inside the star.
Stars are basically nuclear reactors that use hydrogen as a fuel. During its main sequence a star will release energy by converting hydrogen and helium (light elements) into heavier elements.
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.
Our sun is an example of a main sequence star – it’s in the middle of a 10 billion year life span

48. 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
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

49. 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
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

50. This explosion is called a SUPERNOVA
2) If the star becomes a RED SUPERGIANT it will shrink and then EXPLODE, releasing massive amounts of energy, dust and gas.
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)
Before
After
This explosion is called a SUPERNOVA

51. 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 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)

52. 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 “second generation star” – this is because it contains some heavier elements along with hydrogen and helium. These heavier elements would have been the products of a previous star that have been thrown out by a supernova. These heavier elements are also found on planets, indicating that they might have been made from remains of previous stars as well.
The dust and gas thrown off by the supernova will form SECOND GENERATION stars (like our sun) and a new solar system