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1 Wednesday, November 2, 2011

Wednesday, November 2, 2011 - San Jose State University...Wednesday, November 2, 2011 15 Wednesday, November 2, 2011 16 Comet Ikeya-Seki comets do not whiz through sky quickly like

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  • 1

    Wednesday, November 2, 2011

  • The Origin of the Solar System

    Chapter 19

    Wednesday, November 2, 2011

  • I. Theories of Earth’s Origin A. Early Hypotheses B. The Solar Nebula Hypothesis

    II. A Survey of the Solar System A. A General View B. Two Kinds of Planets C. Space Debris D. The Age of the Solar System

    Outline

    Wednesday, November 2, 2011

  • III. The Story of Planet Building A. A Review of the Origin of Matter B. The Chemical Composition of the Solar Nebula C. The Condensation of Solids D. The Formation of Planetesimals E. The Growth of Protoplanets F. Is There a Jovian Problem? G. Explaining the Characteristics of the Solar

    System H. Clearing the Nebula

    IV. Planets Orbiting Other Stars A. Planet-Forming Disks around Other Suns B. Extrasolar Planets

    Outline (continued)

    Wednesday, November 2, 2011

  • Two Kinds of PlanetsPlanets of our solar system can be divided into two very different kinds:

    Terrestrial (earthlike) planets: Mercury,

    Venus, Earth, Mars Jovian (Jupiter-like) planets: Jupiter, Saturn, Uranus,

    NeptuneWednesday, November 2, 2011

  • Terrestrial PlanetsFour inner planets of the solar system

    Relatively small in size and mass (Earth is the largest and most massive)

    Rocky surface

    Surface of Venus can not be seen directly from Earth because of its

    dense cloud cover.Wednesday, November 2, 2011

  • Craters on Planets’ SurfacesCraters (like on our Moon’s surface) are common throughout the Solar System.

    Not seen on Jovian planets because they don’t have a solid surface.

    Wednesday, November 2, 2011

  • The Jovian PlanetsMuch lower

    average density

    All have rings (not only Saturn!)

    Mostly gas; no solid surface

    Wednesday, November 2, 2011

  • Space DebrisIn addition to planets, small bodies orbit the sun:

    Asteroids, comets, meteoroids

    Asteroid Eros, imaged by the NEAR spacecraft

    Wednesday, November 2, 2011

  • 10

    The asteroid Ida and its tiny “moon”: non-spherical shape due to small mass

    Wednesday, November 2, 2011

  • 11

    Asteroid Belt between Mars and Jupiter

    Wednesday, November 2, 2011

  • 12

    Factoids:• Although it might have once contained as much as 10 Earth-masses, the asteroid belt is now estimated to contain something like 1/1000 the mass of the Earth.• A network of telescopes is searching for near-earth asteroids.

    Wednesday, November 2, 2011

  • Comets

    Wednesday, November 2, 2011

  • Comets

    Icy nucleus, which evaporates and gets blown into space by solar wind pressure.

    Wednesday, November 2, 2011

  • Comets

    Mostly objects in highly elliptical orbits, occasionally coming close to the sun.

    Icy nucleus, which evaporates and gets blown into space by solar wind pressure.

    Wednesday, November 2, 2011

  • 14

    Oort Cloud

    In 1950, Jan Oort noticed that: 1. None of the known comets come from interstellar space. 2. There is a strong tendency for cometary orbits to reach out to about 50,000 AU 3. Comets come from random directions

    Wednesday, November 2, 2011

  • 15

    Wednesday, November 2, 2011

  • 16

    Comet Ikeya-Seki

    comets do not whiz through sky quickly like a meteor.

    Wednesday, November 2, 2011

  • 17

    Sketch of the Oort cloud and Kuiper belt

    Warning: not drawn to scale

    Wednesday, November 2, 2011

  • 18

    Wednesday, November 2, 2011

  • 19

    Kuiper Belt:

    • Just past the orbit of Neptune (30AU)• 30-50 AU• ~1,000 known members; examples:

    Pluto (at 40 AU)Quaoar (at 50 AU; ½ size of Pluto)2003 UB313 (97 AU)Eris (size of Pluto at 96.6 AU)

    • About 35,000 objects larger than 100 km expected

    Wednesday, November 2, 2011

  • 20

    Quaoar

    Finding a needle in a haystack

    Wednesday, November 2, 2011

  • 21

    Wednesday, November 2, 2011

  • Meteoroids

    Small (µm – mm sized) dust grains throughout

    the solar system

    Wednesday, November 2, 2011

  • Meteoroids

    Small (µm – mm sized) dust grains throughout

    the solar system

    If they collide with Earth, they evaporate in the

    atmosphere.

    Wednesday, November 2, 2011

  • Meteoroids

    Small (µm – mm sized) dust grains throughout

    the solar system

    If they collide with Earth, they evaporate in the

    atmosphere.

    → Visible as streaks of light: meteors.

    Wednesday, November 2, 2011