# Thought Questions We are finding the space is vast and full of stars. Are we just a small insignificant part of the universe? We are finding the space.

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Thought Questions We are finding the space is vast and full of stars. Are we just a small insignificant part of the universe? We are finding the space is vast and full of stars. Are we just a small insignificant part of the universe?

We are a way that the universe can know itself.

Planet Comparisons Property Terrestrial Planets Jovian Planets Distance CloseFar from the Sun Size SmallLarge Mass SmallLarge CompositionRockySolar-like DensityHighLow

Bodes Law n a simple rule that gives the distances of the planets from the Sun where N=0, 3, 6, 12, 24…for Mercury, Venus, Earth, Mars, etc.

____24(24+4)/10 = 2.8 AU_______ Planet N Bodes Law Radii True Orbital Radii Mercury0(0+4)/10 = 0.4 AU0.39 AU Venus3(3+4)/10 = 0.7 AU0.72 AU Earth6(6+4)/10 = 1.0 AU1.00 AU Mars12(12+4)/10 = 1.6 AU1.52 AU Jupiter48(48+4)/10 = 5.2 AU5.2 AU Saturn96(96+4)/10 = 10.0 AU9.5 AU Uranus192(192+4)/10 = 19.6 AU19.2 AU Neptune??30.1 AU Pluto384(384+4)/10 = 38.8 AU39.5 AU Ceres242.88 AU

What does Bodes Law tell us? n Bode's Law predicted that there should be a planet between the orbits of Mars and Jupiter. n The "missing planet" turned out to be the asteroid belt.

The Origin of the Solar System Four Challenges 1. Patterns of Motion Planets orbit in the same direction......in nearly the same plane......in nearly circular orbits. Most planets rotate in the same direction. Most moons orbit in the same direction. 2. Categorizing Planets Planets are either rocky or gas-rich.

The Origin of the Solar System Four Challenges 3. Asteroids and Comets Most asteroids are found between Mars and Jupiter. Most comets have highly elliptical orbits. 4. Exceptions to the Rules What about Plutos elliptical orbit and composition? What about the odd rotation of Venus and Uranus?

Formation of the Solar System n The solar system is thought to have formed from a cloud of gas and dust in a process know as accretion. n Our Sun is thought to be a second generation star. n What does that mean?

n During the first few million years, matter in the accretion disk of our protosun coalesced… n...in the larger objects called planetesimals, with diameters of about 100 km.

n We see evidence of accretion disk around other stars. For example, Pictoris. For example, Pictoris.

n Collisions of planetesimals dominated the early solar system… n...and these objects combined to form our planets. n We see evidence of early collisions in our solar system in the form of impact craters on the planets and their moons.

Hum…

n In addition to the 9 major planets, there are at least 100 moons in our solar system. n While some of these moons are spherical, most look roughly like potatoes.

n There is still minor debris left over from the formation of the solar system: –asteroids and comets.

Compare these spectra. Spectrum of Hydrogen in Lab Spectrum a Star…..Day 1 What do these spectra tell us about the star? Spectrum a Star…..Day 2 Spectrum a Star…..Day 3 Spectrum a Star…..Day 4

Compare these spectra. Spectrum of Hydrogen in Lab Spectrum a Star…..Day 1 What do these spectra tell us about the star? Spectrum a Star…..Day 2 Spectrum a Star…..Day 3 Spectrum a Star…..Day 4 Spectrum a Star…..Day 5

n Planets outside of our solar system have been found recently using Doppler shifts in the spectra of some stars. n http://observe.phy.sfasu.edu/courses/ast105/lectures105/chapter06/oscillation_of_absorp_line.htm http://observe.phy.sfasu.edu/courses/ast105/lectures105/chapter06/oscillation_of_absorp_line.htm

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End of Section http://observe.phy.sfasu.edu/courses/ast105/lectures105/chapter06/ http://observe.phy.sfasu.edu/courses/ast105/lectures105/chapter06/

Daily Grade Matching n 1. Reddish color of Mars n 2. Red-orange color of Jupiter's belts n 3. Venus' yellowish clouds n 4. Blue-green color of the surface of Uranus and Neptune n 5. The yellow and orange color of Io n a. ammonia clouds n b. sulfur powder n c. sulfuric acid clouds n d. methane clouds n e. iron

Daily Grade Matching n 6. Has an almost featureless surface n 7. The brightest planet seen from Earth n 8. The most distant planet in 1996 n 9. Last planet in our solar system to be discovered n 10. A possible fossil of single-cell life was found on a meteorite from this planet n a. Sun n b. Mercury n c. Venus n d. Earth n e. Mars n f. Jupiter n g. Saturn n h. Uranus n i. Neptune n j. Pluto

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