THE SUN

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THE SUN

• CHAPTER 26

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PROPERTIES OF THE SUN

• DIAMETER 1.4MILLION KILOMETERS
• (110 TIMES THE DIAMETER OF THE EARTH)
• VOLUME MORE THAN ONE MILLION EARTHS
• MASS 745 TIMES GREATER THAN ALL OF THE PLANETS
  PUT TOGETHER

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SUN FACTS

• THE SUN GETS ITS ENERGY FROM FUSION REACTIONS OF
  HYDROGEN
• THE SUN IS 93 MILLION MILES FROM THE EARTH 1 AU
  (astronomical unit)
• IT TAKES 8 MINUTES 20 SECONDS FOR THE SUNS LIGHT
  TO TRAVEL TO THE EARTH

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SUN FACTShttp//solarscience.msfc.nasa.gov/
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FUSION REACTIONS

• FUSION WHEN NUCLEI FROM TWO DIFFERENT ATOMS
  COMBINE
• IT TAKES 4 HYDROGEN NUCLEI TO FUSE TOGETHER TO
  FORM A HELIUM ATOM PLUS ENERGY
• ENERGY mc2
• Energy mass times the speed of light2

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SUNS MATERIAL

• THE SUN IS PLASMA
• PLASMA IS A FORTH STATE OF MATTER CONSISTING OF
  CHARGED PARTICLES
• BECAUSE OF THE INTENSE HEAT GAS IS CHANGED TO
  PLASMA

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THE SUNS LAYERS

• PHOTOSPHERE
• THE VISIBLE SURFACE
• 400KM THICK
• APPEARS GRANULAR
• EACH GRANULE IS ABOUT 1000KM WIDE AND LASTS FOR
  ABOUT 20 MINUTES
• TEMPERATURE IS APX. 6000 C

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PHOTOSPHERE OF THE SUN
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THE SUNS LAYERS

• CHROMOSPHERE (ATMOSPHERE)
• EXTENDS THOUSANDS OF KILOMETERS ABOVE THE
  PHOTOSPHERE
• COLORED RED BY THE GLOWING HYDROGEN
• SOLAR PROMINENCES ARE HUGE CLOUDS OF DENSE MATTER
  SUSPENDED ABOVE THE SURFACE BY MAGNETIC FIELDS
• EXTENDS MILLIONS OF KILOMETERS INTO SPACE
• TEMPERATURE 20,000 C

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• The chromosphere is an irregular layer above the
  photosphere where the temperature rises from
  6000 C to about 20,000 C. At these higher
  temperatures hydrogen emits light that gives off
  a reddish color (H-alpha emission). This colorful
  emission can be seen in prominences that project
  above the limb of the sun during total solar
  eclipses. This is what gives the chromosphere its
  name (color-sphere).

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THE SUNS LAYERS

• CORONA THE THIN OUTER ATMOSPHERE
• IS MILLIONS OF MILES ABOVE THE PHOTOSPHERE
• TEMPERATURE 1 TO 3 MILLION DEGREES C

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CORONA
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FEATURES OF THE SUN

• SUNSPOTS DARK SPOTS ON THE SURFACE (PHOTOSPERE)
• THEY ARE COOLER THAN THE SURROUNDING SURFACE THAT
  IS WHY THEY APPEAR DARK
• THEY MOVE LEFT TO RIGHT
• HAVE A STRONG MAGNETIC FIELD SURROUNDING THEM
• FREQUENCY IS PREDICTABLE FOLLOWING AN 11 YEAR
  CYCLE

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SUNSPOTS
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SOLAR WINDS

• CONSTANT STREAM OF ELECTRICALLY CHARGED PARTICLES
  GIVEN OFF BY THE CORONA
• SOLAR FLARES ARE A SOURCE OF SOLAR WINDS
• CAUSES THE EARTHS MAGNETIC FIELD TO BECOME
  CHARGE AND THEN IT GLOWS CAUSING THE AURORAS

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SOLAR WINDS AND THE AURORA

• EARTHS MAGNETIC FIELD BECOMES CHARGED WHEN THE
  SOLAR WIND BLOWS PAST THE EARTH
• AURORAS OCCUR WHEN THE ELECTRONS GET EXCITED AND
  CHANGE ENERGY LEVELS
• AURORAS ARE COLORFUL PATTERNS IN THE SKY BEST
  SEEN THE CLOSER YOU GET TO THE POLES (THEY OCCUR
  EVERY NIGHT)
• THE MAGNETIC FIELD PROTECTS THE EARTH FROM THE
  HARMFUL EFFECTS OF THE SOLAR WINDS

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AURORA
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SUNS MAGNETISM
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MAGNETISM AND THE SUN

• Magnetism is the key to understanding the Sun.
  Magnetism, or magnetic field, is produced on the
  Sun by the flow of electrically charged ions and
  electrons. Sunspots are places where very intense
  magnetic lines of force break through the Sun's
  surface. The sunspot cycle results from the
  recycling of magnetic fields by the flow of
  material in the interior. The prominences seen
  floating above the surface of the Sun are
  supported, and threaded through, with magnetic
  fields. The streamers and loops seen in the
  corona are shaped by magnetic fields. Magnetic
  fields are at the root of virtually all of the
  features we see on and above the Sun. Without
  magnetic fields the Sun would be a rather boring
  star.

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MAGNETISM AND THE EARTH
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EARTHS MAGNETIC FIELD

• GIANT SHIELD SURROUNDING THE EARTH
• WITHOUT IT THE EARTH WOULD BE HIT BY HARMFUL
  SOLAR PARTICLES

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MAGNETIC POLES/GEOGRAPHIC POLES
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SECTION 2 OBSERVING THE SOLAR SYSTEM

• MODELS OF THE SOLAR SYSTEM
• GEOCENTRIC EARTH CENTERED
• HELIOCENTRIC SUN CENTERED
• ASTRONOMERS
• PTOLEMY GEOCENTRIC
• COPERNICUS HELIOCENTRIC
• TYCHO BRAHE AND KEPLER PLANETARY MOTION
• NEWTON LAW OF GRAVITY
• GALILEO USING THE TELESCOPE TO OBSERVE THE
  HEAVENS

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GEOCENTRIC MODEL

• THIS MODEL STATES THAT THE EARTH IS AT THE CENTER
  OF THE SOLAR SYSTEM
• FOR THE LAST 6000 YEARS ASTRONOMERS WERE
  RECORDING THE MOVEMENTS OF THE STARS AND THE
  PLANETS
• IT APPEARED AS THOUGH THE STARS WERE MOVING
  ACROSS THE SKY SO THEY CONCLUDED THAT THE EARTH
  WAS IN THE CENTER

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GEOCENTRIC MODEL PROBLEMS

• EARLY ASTRONOMERS COULD NOT ACCOUNT FOR THE
  RETROGRADE MOTION OF THE PLANETS
• THE APPARENT BACKWARD MOVEMENT OF THE PLANETS

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PTOLEMYS GEOCENTRIC MODEL

• THE GREEK ASTRONOMER LIVED IN EGYPT IN THE 2ND
  CENTURY A.D.
• PUZZLED BY RETROGRADE MOTION
• DEVELOPED A MODEL OF THE SOLAR SYSTEM WITH THE
  EARTH IN THE CENTER AND PLANETS MOVING IN
  CIRCULAR ORBITS WITH EPICYCLES TO ACCOUNT FOR THE
  RETROGRADE MOTION

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COPERNICUSS HELIOCENTRIC MODEL

• POLISH, LIVED FROM 1473 1543
• PROPOSED A SUN CENTERED SOLAR SYSTEM
• BASIS FOR OUR MODERN UNDERSTANDING OF THE
  UNIVERSE
• THE DIFFERENT SPEEDS OF THE PLANETS ACCOUNTED FOR
  THE RETROGRADE MOTION

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TYCHO BRAHE

• 16TH CENTURY DANISH NOBLEMAN AND OBSERVATIONAL
  ASTRONOMER
• DIDNT USE A TELESCOPE
• USED HIS OWN INSTRUMENTS TO OBSERVE THE MOON,
  PLANETS AND STARS
• USED THE MOVEMENT OF THE MOON AND THE PLANETS
• DIED IN 1601 BEFORE HE COULD FINISH HIS WORK

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JOHANNES KEPLER

• WAS BRAHES ASSISTANT
• TOOK HIS DATA AND APPLIED HIS MATHEMATICAL
  ANALYSIS TO DEVELOP THE LAWS OF PLANETARY MOTION
• THIS EXPLAINS THE ORBITS OF THE PLANETS

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KEPLERS LAWS OF PLANETARY MOTION

• 1ST LAW PLANETS TRAVEL IN ELLIPTICAL ORBITS
  AROUND THE SUN
• AN ELLIPSE HAS 2 FOCI POINTS
• THE SUN IS ONE FOCUS POINT
• A PLANETS DISTANCE FROM THE SUN WILL CHANGE
  THROUGHOUT ITS ORBIT

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KEPLERS 2ND LAW EQUAL AREA LAW

• A LINE CONNECTING EARTH TO THE SUN WILL PASS OVER
  EQUAL AREAS OF SPACE IN EQUAL TIMES
• THIS MEANS THAT THE CLOSER A PLANET IS TO THE SUN
  IN ITS ORBIT THE FASTER IT WILL MOVE
• SO A PLANET CHANGES SPEED THROUGHOUT ITS ORBIT

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KEPLERS 3RD LAW HARMONIC LAW

• P2 D3
• P THE TIME IT TAKES A PLANET TO TRAVEL ONE
  ORBIT AROUND THE SUN
• D DISTANCE FROM THE SUN
• THIS MEANS THAT THE PERIOD OF A PLANET SQUARED IS
  EQUAL TO THE CUBE OF ITS MEAN DISTANCE FROM THE
  SUN
• YOU CAN USE THIS FORMULA TO FIND THE DISTANCE TO
  A PLANET IF THE PERIOD IS KNOWN OR FIND THE
  PERIOD IF THE DISTANCE IS KNOWN

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3RD LAW

• SO, THE FARTHER A PLANET IS FROM THE SUN THE
  LONGER IT TAKES FOR IT TO GO AROUND THE SUN
• ONE REASON IS THAT THE ORBIT IS LARGER
• PLANETS THAT ARE FARTHER AWAY MOVE SLOWER

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NEWTONS LAW OF GRAVITY

• EVERY MASS EXERTS A FORCE OF ATTRACTION ON EVERY
  OTHER MASS, AND THE STRENGTH OF THAT FORCE IS
  PROPORTIONAL TO EACH OF THE MASSES AND INVERSELY
  PROPORTIONAL TO THE DISTANCE BETWEEN THEM

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LAW OF GRAVITY

• BECAUSE THE SUN IS SO MASSIVE ITS FORCE AFFECTS
  THE PLANETS ORBITS
• DRAWS THE PLANETS TOWARD IT AND DEFLECTS THE
  STRAIGHT LINE PATHS THEY WOULD FOLLOW UNDER
  NEWTONS FIRST LAW OF MOTION