Transcript Chapter 22
Chapter 22 The Sun and Its Solar System Handy Dandy Earth Science Reference Tables Page 15 HERTZSPRUNG-RUSSEL DIAGRAM Properties of the Sun • An average size yellow star • fairly cool compared to other stars • diameter is approx. 110 times larger than Earth’s, with a volume that hold more than 1,000,000 Earths. (yes, that’s one million!!!) • Light traveling from the sun takes approx. 8 minutes 20 seconds to reach Earth! • surface temperature is approx. 5,500 C and its interior temperature is believed to be 15,000,000 C!! Examine the sun at different wavelengths Sunspots & Prominences • Sunspots are regions of intense magnetic fields • Sunspot temperatures are cooler than photosphere, which makes them appear as dark spots • Prominences are regions along a magnetic field line where conditions are right for light to be emitted • Huge, arching columns of gas often appearing above sunspots Solar Flares • Occasionally, kinks and stresses occur on magnetic field lines discharging amounts of energy (known as Solar Flares) • The amount of energy released is equivalent to a 2 billion megaton bomb • Flares release large numbers of particles into the corona Source of the Sun’s Energy • The process of NUCLEAR FUSION • Einstein explained this process as E = MC² (matter can be converted into energy) • The hydrogen molecules that the sun is made of fuse together to form a helium atom. When this occurs, energy is given off! SUN – FUSION – atoms FUSE together **It is estimated that the sun has enough mass for nuclear fusion to continue for 5 billion more years! 3 Heliums (atomic # 2) fusing into 1 Carbon (atomic #6) at the core Hydrogen burning shell energy The Solar System • All of the planets travel around the sun in the same direction, but not at the same speed • Because of this, there may be times when Earth passes a planet in its orbit • The planet will then appear to be moving in the opposite direction (backward) • This is called retrograde motion – The planet is not really moving backward (think about two cars traveling side by side…when one car speeds up, the other car may appear to move backward) Retrograde Motion Animation Retrograde Motion Animation Solar System Models • Geocentric (Geo=Earth) – ancient people believed that the Earth was the center of the universe, and all planets and stars moved in orbits around Earth (remember, the sun appears to rise and set each day when it is really the Earth spinning that causes this) • Heliocentric (Helio = Sun) – this is the accepted model. It states that the sun is the center of the solar system, and all of the planets move around the sun Geocentric Model • The Geocentric Model remained the accepted theory of the orientation of the universe for so long because all celestial movements (including retrograde motion, stars, sun, moon, comets, etc. could be explained via a Geocentric model. The only motion that can’t be explained by a Geocentric model is Foucault’s Pendulum - because in the Geocentric Model – THE EARTH DOES NOT ROTATE!!!!!!!! • (MORE ON Foucault’s Pendulum later…) Kepler’s 3 Laws of Planetary Motion First Law – Elliptical Orbits • All planets travel around the sun in an elliptical orbit (LAB) with the sun as one of the foci • Because the orbits are not perfectly circular, the distance between the sun and the planet changes • Eccentricity is a measure of how stretched out the planet’s orbit is (Ref. Tables P. 1, LAB) 0.0 .25 .50 .75 .90 Formula – Page 1 of ESRT’s eccentricity = dist. between foci length of major axis These measurements are made in cm, m or km – and are either provided to you or you measure them on a paper drawing of the elliptical orbit…. VIF • Even though the planet shapes are mathematically elliptical, all of the planets orbits (except for Mercury eccentricity = 0.206 & Pluto – eccentricity = 0.250) appear to be perfect circles when looking at their orbital shapes from space or when drawing them on paper… Second Law – Equal Area • When the planets are closest to the sun they move faster, and when they are farthest from the sun they move slower • Because of this, 2 imaginary triangles drawn between the sun and the planet at two points in the planet’s orbit that cover any 2 equal lengths of time would cover an equal amount of area • HUH??????????? You say • …here are some examples…. Here’s an illustration… Third Law – Harmonic Law • the farther a planet is from the sun, the longer its period of revolution (the longer it takes to go around the sun – common sense) – #1 – it goes slower – #2 – it has further to go (DUH!!!) • Kepler stated this using the formula P² = D³, where P is the period of revolution (in Earth years) and D is the distance from the sun (in AU’s) PS – This is how the planet Mercury was named…Mercury was the Messenger of the Gods and is the guy with the wings on his feet…he was fast… ETC… VIF - Aphelion & Perihelion • When a planet is closest to the sun it is called perihelion, when it is farthest from the sun it is called aphelion (think Aphelion = Away) • Earth’s perihelion is Jan. 4th-ish – after the first day of Winter, and Earth’s aphelion is July 4th-ish – after the first day of Summer. The Solstices and Aphelion/Perihelion DO NOT JIBE!!!!! Disclaimer – this illustration is EXTRMEMELY EXAGGERATED!!!!!!!!!!!!!!! Newton’s Universal Law of Gravitation • the force of gravity between any two objects is directly related to the masses of the two objects, but inversely related to the square of the distance between the centers of the two objects F = force of gravity between 1 and 2 F = Gm1m2 r2 G= Gravitational Constant (9.8 m/s2) r = distance between objects m = masses of objects Simplified: • The larger the objects, the greater the force of gravity between them • Also, the greater the distance between the two objects, the less the force of gravity pulls on them Here we have vector addition…wait ‘til Physics!!!