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Lecture 3

Biology Lecture 3 Outcomes

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Western University
Biology 1002B
Tom Haffie

Lecture 3 Hubble deep field: Hubble telescope sits in a orbit around the earth, looks at what’s outside the milky way, (image shows all the other galaxies) The Universe, The Galaxy  Andromeda M31 – another galaxy  Speed of light = 1.1 billion km/h  Light year = 9,460,730,472,580 Proxima Centauri  Closet star  4.22 light years (39,922,000,000,000 km)  150,000 years away Radio waves: one form of electromagnetic radiation, radio waves travel the speed to light so we can use them for astronomy.  Only means fast enough to observe evidence of aliens  Can pick up any transmissions of radio waves sent out by life else where o Must filter out background noise (stars)  Any radio waves produced by a society would not be random, would have structure  SETI: search for extraterrestrial intelligence The Drake Equation: N = Number of advanced civilizations in our galaxy N s Number of stars fp= the fraction of those stars that have planets n = number of planets that can potentially support life e fl= the fraction of those planets that develop life fi= the fraction of planets that develop intelligent life fc = the fraction of planets willing and able to communicate L = average lifetime of a civilization Ns= 100 billion  Kepler Mission: to detect extra solar planets  Looks at one narrow slice of milky way, and watches 150 stars  Detects the dip in the brightness of these starts  Transit method: Looking for a regular decrease in brightness (planets going around the star)  2326 planets detected in that narrow slice Fp= 0.5: planet formation is a natural consequence of star formation, they occur concurrently  set Fp= 0.5  0.5 because star and planets form concurrently  therefore we have 50 billion stars which have planets Ne= 2: mass and distance from parent star are important criteria  planet too big= giant gas ball, too much attraction of gases  small planet= not enough gravity and gases escape  too far away from star= too cold  too close= too hot  there’s a optimal habitable zone  has everything to do with water, habitable is between 0-100C, because water is in its liquid states  Set Ne=2 for each planetary system  Therefore 100 billion planets could support life Water: Oxygen is electronegative making water polar covalent, but unequal sharing  Defines Habitable zone  Based on its molecular weight, should be a gas at room temperature, not liquid  Reason it’s a liquid is because it takes a lot of energy to break hydrogen bonds to make it a gas Emergent properties o Cohesion:  Many water molecules are attracted together form H bonds  Causes water to be a liquid at moderate temps  Caused surface tension – a measure of how hard it is to break the surface of a liquid  Ex. Water strider o Adhesion:  Is the attraction of water to other polar substances  Due to H bonding  Capillary action  When water is drawn into a narrow tube, rises against gravity  Adhesion and cohesion forces combine to pull water up plants o High Heat Capacity:  Water’s specific heat is 9x that of iron  Water has a high specific heat, which allows it to minimize temperature
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