2Big Bang 14 thousand million years ago Theory was proposed by the Catholic Priest George Lemaitre
3The solar system was formed from clouds of gases and dust in space about 5 thousand million years ago
4The Earth must be older than its oldest rocks which are about 4 thousand million years old
5The Sun is a Star The Sun is a star in the Milky Way galaxy All stars have a life cycleThere are thousands of millions of galaxies, each containing thousands of millions of stars, and that all of these make up the Universe
6Fusion Fusion of hydrogen nuclei is the source of the Sun’s energy All chemical elements larger than helium were made in earlier stars
7Diameters and Motion Biggest > Smallest Milky Way Galaxy:light yearsSpins around a black holeSun:1.4 million kmCentre of Solar systemPlanet:kmOrbits sunMoons:3500kmOrbits PlanetsAsteroids:1000kmOrbits Sun (between Mars and Jupiter)Comets:3kmOrbits SunDiameters and Motion Biggest > Smallest
8How we know about the Universe Information about distant stars and galaxies comes only from the radiation astronomers can detectLight pollution interferes with observations of the night sky
9Speed of Light Light travels at 300 000 km/s The speed of light means distant objects are observed as younger than they are nowLight-year = the distance travelled by light in a year
10Parallax or Relative Brightness Can be used to measure the distance to starsThe difficulty of observations makes the distance of stars and galaxies uncertain
11Hubble’s Law All Galaxies are moving away from us. The further away the galaxy, the quicker it is moving.This suggests that the universe is expanding
12Future of the UniverseUnderstand why the ultimate fate of the Universe is difficult to predict.
13Aliens Astronomers have detected planets around nearby stars Even if a small proportion of stars have planets, many scientists think that it is likely that life exists elsewhere in the UniverseNo evidence of alien life has so far been detected
14Asteroid CollisionsThe frequency of a 15km asteroid hitting Earth is 1 in every 65 million years.The last one was in Mexico, 65 million years ago. Evidence indicates that this led to the extinction of the dinosaurs
15Structure of the EarthBe able to label the Core, Mantle, Crust
16Theory of Continental Drift Proposed by Alfred WegenerThe movement of the Earth's continentsEvidence for it:Geometric fit of continentsMatching fossilsMatching mountain chainsMatching rocks
17Reasons for the rejection of Wegener’s theory by geologists of his time: Movement of continents not detectableWegener was an outsider to the community of geologistsToo big an idea from limited evidenceSimpler explanations of the same evidence
18Seafloor Spreading A consequence of movement of the solid mantle Seafloors spread by about 10 cm a yearProduces a pattern in the magnetism recorded in ocean floors, due to reversals of the Earth’s magnetic field and solidification of molten magma at oceanic ridges.
19Tectonic Plates The following occur at plate boundaries: Volcanoes: Plates moving apartMountains: Plates move towards one another. One plate dives underneath anotherEarthquakes: Plate slide past one anotherRock processes seen today explain past changesContinents would be worn down to sea level, if mountains were not being continuously formed. Therefore the above are an important part of the rock cycle
20Rocks provide evidence for changes in the Earth Erosion, sedimentation, fossils, folding, radioactive dating, craters.
21Actions that Public Authorities can take to Reduce Damage caused by Geo-Hazards Enforce building regulations to limit the effect of earthquakesprovide education and trainingmonitor natural hazards in the local area to look for early signs of earthquakes or volcanic activitytake part in international research
22DataData statements tell you facts, and may contain measurements. For example, look at these three statements:Asteroids are small objects orbiting the SunSome asteroids have orbits close to the EarthThe dinosaurs died out at about the same time as a large crater was made in Mexico
23ExplanationsExplanations seek to explain the data, and formulating an explanation requires imagination and creativity.One explanation is that an asteroid collision may have killed off the dinosaurs. The asteroid impact would have created dust which blocked out the Sun.
24PredictionsA good explanation will explain data, and link together things which were not thought to be related. It should also make predictions.Asteroids often contain the rare metal iridium - dataA huge asteroid impact would send iridium dust throughout the world - predictionSedimentary rocks from the time the dinosaurs died out contain iridium - dataWhen the asteroid crashed, the iridium came from the dust which blocked out the Sun - explanation
25ObservationsData and predictions can be used to test an explanation, but you have to be careful. When an observation agrees with the prediction, it makes you more confident in the explanation, but it does not prove that the explanation is true.The opposite is also correct. When an observation disagrees with a prediction, it makes you less confident in the explanation, but it does not prove that the explanation is wrong. The data may be faulty.
26Other TheoriesThe asteroid theory is not the only theory about the death of the dinosaurs.There were huge volcanic eruptions in India at the time the dinosaurs died out (data)Big volcanic eruptions cause dust clouds which block out the Sun (data)The big Indian eruptions could have killed out the dinosaurs by cooling the Earth (explanation)
27Publishing and Peer Review Scientists report their ideas to the scientific community, which is made up of all the other scientists. They present them at conferences and then write them up in journals or books.At conferences, other scientists will listen and debate the new ideas. Before journals or books are published, other expert scientists read the new ideas and decide if they are sensible. This is called peer review.
28Repeating Experiments Scientists do not usually accept the results of experiments until someone else has repeated the experiment to get the same results.It is hard to set up experiments in geology and astronomy, so new theories here need support from different observations
29Different Explanations Data often allows more than one possible explanation, so different scientists can have different explanations for the same observations.Wegener’s ideas could certainly explain similar fossils in different continents, but other geologists thought that there were once ‘land bridges’ between continents, allowing animals to travel between them.The different backgrounds of different scientists can affect their judgements, so they may have quite different explanations for the same data.
30New Explanation Become Accepted A scientific explanation is rarely abandoned just because some data does not correspond to it. It is safer to stick with a theory that has worked well in the past.Old geological theory - mountains as wrinkles made by the Earth shrinking as it cools down.No clear explanation how continents could move about.In the 1950s, evidence from magnetism in the ocean floor showed that the seafloors were spreading by a few centimetres each year. This showed movement of large parts of the Earth’s crust, now called tectonic plates.