2 Contents The Solar System Stars Solar Systems, Galaxies & the Universe CometsLife Cycle of StarsRed-ShiftHistory of the UniverseFuture of the UniverseSETI
3 The Solar SystemMyVeryEfficientMindJustStoresUpNinePlanets
4 Stars Stars are burning balls of gas e.g. our Sun Stars give out light This light reflects off planets so we can see themPlanets are much smaller than stars… but they seem much bigger as they are much closerThe 9 planets orbit the sun, Earth orbits the Sun once a year
5 Stars Stars are burning balls of gas e.g. our Sun Stars give out light This light reflects off planets so we can see themPlanets are much smaller than stars… but they seem much bigger as they are much closerThe 9 planets orbit the sun, Earth orbits the Sun once a year
6 Solar Systems, Galaxies & the Universe Our Sun is one of millions of stars that orbit the centre of the UniverseThe Milky Way is one of more than a billion galaxies in the UniverseThe Universe is expanding
7 Comets Comets appear every few years Comets have highly elliptical orbits around the SunComets are visible when they are close to the SunA comet’s orbit is fastest near the Sun due to the Sun’s gravity. It slows as it moves further away from the SunTail is pushed away from sun by solar pressureTail is made of ice and rock
8 Life Cycle of Stars cools and contracts Layers of dust & gas are ejectedclouds of dust & gasHHeheat & lightejectedstarH runs outswellsred = coolerdense core = neutron starexplodesupernovaor black hole (crushes atoms!)
9 Red-ShiftLight from distant galaxies is shifted towards the red end of the spectrumFrequencies become lower as they move away (like the Doppler Effect for sound)Further away = greater red-shiftUniverse is expandingAlso evidence from microwaveradiation (background radiation)that Universe is cooling
10 History of the Universe 1. Steady State TheoryUniverse has always existed…and Universe will always existNo convincing evidenceNot much support for the Steady State Theory
11 History of the Universe 2. Big Bang TheoryUniverse was compressed and exploded – Big BangOccurred 15 billion years agoEstimated by current rate of expansionExpansion is slowing due to gravity
12 Future of the Universe According to the Big Bang Theory… 1. Expand ForeverIf too little mass for gravity to stop expansion…Universe will expand and spread out into eternity2. Big CrunchIf enough mass to stop expansion, universe will contractBig Crunch!Big Crunch would produce another Big Bang… and so on!
13 Scientists search for extra terrestrial intelligence SETIScientists search for extra terrestrial intelligenceRadio SignalsSETI looks for radio wavelength signals being sent to EarthThese signals can only be sent by a transmitterSETI has been running for 40 years… not found anythingNow searching for laser signals too!Robots Collect Photos and SamplesSpacecraft are sent to planets to look for microorganismsCollect samples and take photosScientists analyse samples and look for fossils etc.
14 Summary Solar system – 9 planets & 1 star Stars emit light, planets reflect this lightSolar systems are in galaxies which are in the UniverseComets (rock and ice) have long elliptical orbits around SunLife cycle of stars – differs for massive & small starsRed-shift – evidence for fast expansion of galaxiesHistory of the Universe – Big Bang or Steady StateFuture of the Universe – Big Crunch or Eternal ExpansionSETI – Radio signals, laser signals, collect photos & samples