1. What do waves (like light)transport? 2. Based on what you know about light- how do rainbows form?  Homework: Read  TEST OCT › Kepler’s Laws › Solar system formation › Light › Sun  Guided Reading packet. Due before next test-OCT 11/12.

 The sun is the center of our solar system and contains 99.85% of the solar system’s mass.  All planets travel in elliptical path’s around the sun in the same direction. (Thanks Kepler!)  Mercury travels the fastest and Neptune travels the slowest.

Imagine the orbit as a sheet of paper. Seven planets are within 3 degrees of the sun’s equator. Mercury is 7 degrees.

 “Earth like”  Inner planets  Relatively small and rocky.  Mars, Earth, Venus, and Mercury

 “Jupiter like”  Outer planets  Huge gas giants  Jupiter, Saturn, Uranus, Neptune

 Size is the biggest difference between terrestrial and jovian planets.  They also differ in density, chemical make-up, and rate of rotation.  Terrestrial planets average 5x’s density of water.  Jovian averages 1.5x’s density of water. Saturn is 0.7-would float in water.

 Gases-primarily H and He  Rocks-silicate minerals and metallic irons  Ices-ammonia, methane, carbon dioxide, and water  Terrestrial planets are mainly rocky and metallic with minor gases and ices.  Jovian are mainly gases and some have rocky metallic cores.

 Jovian planets have thick atmospheres and terrestrial planets have meager atmosphere’s in comparison.  The ability to retain an atmosphere depends on the mass and temperature of a planet. › Relatively warm bodies with smaller gravity loses their gases. On Earth, gases represent a small part of our mass.

 Jovian planets have cold temperatures and greater surface gravities so gases have a harder time escaping.

 Nebular theory  Our solar system formed from NEBULA (clouds of gas and dust in space).  They rotate slowly and contract gravitationally.  As it contracts it starts to spin faster.

 As the speed of the nebula increased the disc began to flatten and matter began to concentrate.  This matter concentration formed the sun and all of the planets.

 Bits of matter collided and bumped together making PLANTESIMALS-Small irregular shaped baby planets formed from colliding matter.  They kept colliding and grew larger, gained gravity, and eventually became true planets.  Inner planets-close to sun=hot so only metals and silicates started to bead together.  Outer planets-cold and ices formed.

 The terrestrial planets are closer to the sun so the rocks and metals came together. It was too hot for the gases and ices to come together.  Jovian planets are far from the sun so they were very cold! They accumulated rocks and metals, as well as, gases and ices.  They grew larger and larger and began to get a strong gravity and captured even the lightest of gases.

 Most of what we know about space has been from studying light. 1. Total energy output 2. Surface temperature 3. Radius 4. Chemical composition 5. Velocity relative to Earth 6. Rotation period

 Electromagnetic radiation includes gamma rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves, and radio waves.  The ELECTROMAGNETIC SPECTRUM is the arrangement of electromagnetic radiation according to wavelength

 Sometimes light behaves like WAVES, and in others, like particles.  In the wave sense, light can be thought of as swells in the ocean. This motion is characterized by a property known as wavelength, which is the distance from one wave crest to the next.  Other times it behaves as PHOTON- a small packet of light energy.

 SPECTROSCOPY is the study of the properties of light that depend on wavelength.  A continuous spectrum is an uninterrupted band of light emitted by an incandescent solid, liquid, or gas under pressure.  An absorption spectrum is a continuous spectrum produced when white light passes through a cool gas under low pressure. The gas absorbs selected wavelengths of light, and the spectrum looks like it has dark lines superimposed.

 An emission spectrum is a series of bright lines of particular wavelengths produced by a hot gas under low pressure.  When the spectrum of a star is studied, the spectral lines act as “fingerprints.” These lines identify the elements present and thus the star’s chemical composition.  From emission spectrum they have identified 60 elements in the sun.

 The DOPPLER EFFECT is the apparent change in frequency of electromagnetic or sound waves caused by the relative motions of the source and the observer.  In astronomy, the Doppler effect is used to determine whether a star or other body in space is moving away from or toward Earth.  Large shift=high speed  Small shift=slowed

1. Use the spectroscope to look at the light bulb in the lamp and the florescent lights in the ceiling. Compare what you see. Record in your notebook. 1. Fluorescent classroom light 2. Incandescent 3. Natural light 4. Blue, yellow, red and green filters 5. Compact fluorescent 2. How does the spectrum differ between the different sources of light?