Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37NSCI 314LIFE IN THE COSMOS2 – ENERGYTHE NATURE OF LIGHTBASIC ASTRONOMYSTARS AND THEIR SPECTRADr. Karen KolehmainenDepartment of PhysicsCSUSBCOURSE WEBPAGE:http://physics.csusb.edu/~karenTEMPERATUREMOLECULES ARE ALWAYS IN MOTION.THE DIRECTIONS OF MOTION ARE RANDOM. DIFFERENT MOLECULES MOVE IN DIFFERENT DIRECTIONS.THE HIGHER THE TEMPERATURE OF AN OBJECT, THE FASTER THE MOLECULES INSIDE IT ARE MOVING, ON THE AVERAGE.AT A GIVEN TEMPERATURE, NOT ALL MOLECULES MOVE AT THE SAME SPEED. SOME MOVE FASTER THAN AVERAGE, AND SOME MOVE SLOWER THAN AVERAGE.IMAGINE A COLLECTION OF MOLECULES, SOME LIGHTER AND SOME HEAVIER (EXAMPLE: AIR), ALL AT THE SAME TEMPERATURE. THE LIGHTER MOLECULES ARE FASTER AND THE HEAVIER MOLECULES ARE SLOWER, ON THE AVERAGE.DENSITY AND PRESSUREDENSITY = MASS / VOLUME–VOLUME IS THE AMOUNT OF ROOM (IN 3-D) THAT SOMETHING TAKE UPPRESSURE = FORCE / AREA–THE ATMOSPHERIC PRESSURE ON THE SURFACE OF THE EARTH IS A RESULT OF THE WEIGHT OF THE AIR ABOVE US PRESSING DOWN ON US.–IF YOU MOVE TO A HIGHER ELEVATION, THERE IS LESS AIR ABOVE YOU, SO THE PRESSURE IS LOWER. THIS ALLOWS THE AIR MOLECULES TO SPREAD FARTHER APART, SO THE DENSITY IS ALSO LOWER.ATMOSPHERIC PRESSURE AND DENSITY VARY FROM PLANET TO PLANET.THE DUAL NATURE OF LIGHT: PARTICLES AND WAVESSOMETIMES LIGHT BEHAVES LIKE A WAVE (AN OSCILLATING ELECTROMAGNETIC FIELD).SOMETIMES LIGHT BEHAVES LIKE A STREAM OF PARTICLES.WHICH IS IT? NEITHER IS REALLY CORRECT, BUT BOTH ARE USEFUL WAYS TO THINK ABOUT IT.IF THIS SKETCH REPRESENTS A WATER WAVE, THE HEIGHT OF THE WATER CHANGES AS YOU MOVE TO THE RIGHT OR LEFT. IF IT'S A SOUND WAVE, THE DENSITY AND PRESSURE OF AIR (OR SOME OTHER MATERIAL) CHANGES AS YOU MOVE TO THE LEFT OR RIGHT. IF IT'S A LIGHT WAVE, THE STRENGTH OF AN ELECTROMAGNETIC FIELD CHANGES AS YOU MOVE TO THE RIGHT OR LEFT. THE WAVE TRAVELS EITHER TO THE RIGHT OR LEFT. ALL WAVES CARRY ENERGY AS THEY MOVE.SPEED OF LIGHT: c = 300,000 km/s = 1 light year / year(SAME SPEED FOR ALL LIGHT WAVES IN A VACUUM)THE WAVE NATURE OF LIGHTWAVELENGTH = DISTANCE BETWEEN TWO ADJACENT PEAKS FREQUENCY = NUMBER OF WAVES OR PEAKS PASSING BY A GIVEN LOCATION PER SECOND1 Hertz = 1 wave per second passing by1 kHz = 1,000 Hz1 MHz = 1,000 kHz = 1,000,000 HzWAVELENGTH x FREQUENCY = SPEED OF WAVE THE WAVE NATURE OF LIGHTWAVELENGTH x FREQUENCY = SPEED OF WAVE SINCE THE SPEED IS THE SAME FOR ALL LIGHT WAVES (c), LARGER FREQUENCY MEANS SMALLER WAVELENGTH, AND VICE VERSA.FOR LIGHT WAVES, FREQUENCY AND WAVELENGTH ARE RELATED TO COLOR.-THE SMALLER THE WAVELENGTH, THE LARGER (OR HIGHER) THE FREQUENCY, AND THE BLUER THE COLOR. -THE LARGER THE WAVELENGTH, THE SMALLER (OR LOWER) THE FREQUENCY, AND THE REDDER THE COLOR. THE WAVE NATURE OF LIGHTAMPLITUDE = HEIGHT OF THE WAVE (TECHNICALLY, IT'S DEFINED AS HALF OF THE TOTAL HEIGHT)FOR LIGHT WAVES, THE AMPLITUDE IS RELATED TO THE BRIGHTNESS:- THE LARGER THE AMPLITUDE, THE BRIGHTER THE LIGHT. - THE SMALLER THE AMPLITUDE, THE FAINTER THE LIGHT. THE WAVE NATURE OF LIGHTTHE PARTICLE NATURE OF LIGHTA PARTICLE OF LIGHT IS CALLED A PHOTON.A PHOTON CARRIES ENERGY.THE AMOUNT OF ENERGY THAT EACH PHOTON HAS IS RELATED TO THE COLOR OF THE LIGHT (AND THEREFORE ALSO TO WAVELENGTH AND FREQUENCY OF THE CORRRESPONDING WAVE).THE LARGER THE ENERGY PER PHOTON – THE SHORTER THE WAVELENGTH– THE HIGHER THE FREQUENCY– THE BLUER THE COLORTHE SMALLER THE ENERGY PER PHOTON– THE LONGER THE WAVELENGTH– THE LOWER THE FREQUENCY– THE REDDER THE COLORLONG WAVELENGTH --> LOW FREQUENCY --> LOW ENERGY PER PHOTONSHORT WAVELENGTH --> HIGH FREQUENCY --> HIGH ENERGY PER PHOTON ELECTROMAGNETIC SPECTRUMTYPEGAMMA RAYS X- RAYSULTRAVIOLET VISIBLE LIGHTINFRAREDMICROWAVETV & FM RADIOAM RADIOWAVELENGTHSIZE OF ATOMSIZE OF ATOMVIRUSBACTERIADUST1 cm1 m100 mFREQUENCYVERY HIGHVERY HIGHHIGHBILLION MHzMILLION MHz1000 MHz100MHz1000 kHzPURPLEBLUEGREENYELLOWORANGEREDENERGYENERGY IS WHAT MAKES THINGS HAPPEN.CONSERVATION OF ENERGY: ENERGY CANNOT BE CREATED OR DESTROYED.ENERGY CAN BE CHANGED FROM ONE FORM TO ANOTHER. ENERGY CAN BE TRANSFERRED FROM ONE OBJECT TO ANOTHER.FORMS OF ENERGYKINETIC ENERGY – ENERGY OF MOTIONPOTENTIAL (STORED) ENERGY–ELASTIC (EXAMPLE: STRETCHED OR COMPRESSED SPRING)–GRAVITATIONAL–ELECTRICAL–CHEMICAL–NUCLEARLIGHTSOUNDTHERMAL (HEAT) ENERGY – KINETIC ENERGY OF RANDOM MOTION OF MOLECULESMASS (E = m c2)SOME BASIC ASTRONOMYSTAR: A VERY LARGE , HOT BALL OF GAS THAT EMITS LARGE AMOUNTS OF LIGHT. THE LIGHT AND HEAT ARE PRODUCED BY NUCLEAR FUSION (SMALL NUCLEI COMBINING TO PRODUCE LARGER NUCLEI) OCCURRING IN THE CENTER OF THE STAR.PLANET: A FAIRLY LARGE OBJECT (BUT MUCH SMALLER THAN A STAR) THAT ORBITS AROUND A STAR. IT CAN BE ROCKY OR GASEOUS. THERE IS NO NUCLEAR FUSION OCCURRING INSIDE. MOON: A SMALLER OBJECT THAT ORBITS AROUND A PLANET.SOME BASIC ASTRONOMYEARTH: THE PLANET UPON WHICH WE LIVE.SUN: THE STAR AROUND WHICH THE EARTH ORBITS.SOLAR SYSTEM: OUR SUN, THE 8 PLANETS AND SMALLER BODIES (DWARF PLANETS, COMETS, ASTEROIDS, ETC.) THAT ORBIT IT, AND THE MOONS THAT ORBIT THE PLANETS.GALAXY: A LARGE CLUSTER OF STARS (1 MILLION TO 1 TRILLION STARS). MANY OF THESE STARS HAVE THEIR OWN SOLAR SYSTEMS.THE MILKY WAY: THE GALAXY IN WHICH OUR SOLAR SYSTEM IS LOCATED. IT CONTAINS ABOUT 400 BILLION STARS, PLUS THE PLANETS AND SMALLER BODIES ORBITING THESE STARS.SOME BASIC ASTRONOMYUNIVERSE: EVERYTHING THAT EXISTS. WITH POWERFUL TELESCOPES, WE CAN SEE ABOUT 100 BILLION OBSERVABLE GALAXIES. THE TOTAL NUMBER OF GALAXIES IN THE UNIVERSE IS LIKELY TO BE MUCH HIGHER, PROBABLY AT LEAST 1 TRILLION. BIG BANG: AN EXPLOSION THAT STARTED THE UNIVERSE APPROXIMATELY 13.7 BILLION YEARS AGO. ALL OF THE MATTER IN THE UNIVERSE WAS EXPELLED OUTWARD FROM THE EXPLOSION. GALAXIES ARE STILL MOVING APART FROM EACH OTHER AS A RESULT. (BY COMPARISON, OUR SOLAR SYSTEM IS ONLY 4.6 BILLION YEARS OLD.)YMOTIONS IN THE SOLAR SYSTEMEACH PLANET SPINS OR ROTATES ON ITS OWN AXIS, PRODUCING DAY AND NIGHT. THE EARTH SPINS ONCE EVERY 24 HOURS (1 DAY).EACH PLANET ORBITS OR REVOLVES AROUND THE SUN. THE EARTH COMPLETES ONE ORBIT IN 365