Lec18-Mar25 - 3/25/11 Discussion Ques7on When we toss...

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Unformatted text preview: 3/25/11 Discussion Ques7on When we toss 40 dice, about how many are expected to land “hole side up”? Astro 109 Lecture 18: Forma7on of the Solar System March 25 A.  B.  C.  D.  E.  1 3 13 20 30 Mar. 25 Discussion Ques7on Discussion Ques7on If about 1/3 of the dice “decay” on each roll, about how many rolls cons7tute one half ­life? How does the theory of the forma7on of the solar system account for all the major planets lying in one plane? A.  B.  C.  D.  E.  A.  It happened by chance. B.  The Sun’s gravity pulled the planets into a plane aYer they formed. C.  Planetesimal impacts forced the planets into a plane. D.  The solar nebula fla\ened into a disk. E.  Planets with orbits out of the plane were ejected. 1 2 3 4 5 Mar. 25 Mar. 25 Key Concepts Solar nebula •  Solar nebula, protoplanetary disk As a rota7ng cloud contracts, it spins faster and se\les into a disk. •  Building planets: planetesimals, accre7on •  Evidence for a violent past Mar. 25 Mar. 25 1 3/25/11 Discussion Ques7on What physical process caused the solar nebula to form a disk as it collapsed? A.  B.  C.  D.  E.  conserva7on of energy conserva7on of eccentricity conserva7on of angular momentum nuclear fusion Kepler’s first law Mar. 25 Mar. 25 Seeing protoplanetary disks Mar. 25 Forma7on of planets Mar. 25 Forma7on of planets Mar. 25 Forma7on of planets Mar. 25 2 3/25/11 Forma7on of Jovian planets Forma7on of terrestrial planets Mar. 25 Mar. 25 Discussion Ques7on Discussion Ques7on Which statement best describes the origin of the terrestrial planets? Which statement best describes the origin of the Jovian planets? A.  Ini7ally gentle collisions between par7cles of ice and dust led to the build ­up of massive cores which then captured a lot of hydrogen and helium. B.  Rocky dust par7cles combined to form planetesimals that later merged into a few large objects. C.  Hydrogen and helium collapsed to form large objects that later captured a lot of ice. D.  There were four solid objects in the gas cloud before it started to collapse. E.  They are debris leY over from the forma7on of the inner planets. A.  Ini7ally gentle collisions between par7cles of ice and dust led to the build ­up of massive cores which then captured a lot of hydrogen and helium. B.  Rocky dust par7cles combined to form planetesimals that later merged into a few large objects. C.  Hydrogen and helium collapsed to form large objects that later captured a lot of ice. D.  There were four solid objects in the gas cloud before it started to collapse. E.  They are debris leY over from the forma7on of the inner planets. Mar. 25 Mar. 25 Discussion Ques7on Forma7on of terrestrial planets Is there any debris leY over from the forma7on of the solar system? A.  No, all the material was used up in forming the planets. B.  No, all leYover material was burned up in the Sun. C.  No, all leYover material was ejected from the solar system by Jupiter and Saturn. D.  Yes, but we cannot see it because it is too small. E.  Yes, there is debris leY over in the form of asteroids and comets. Mar. 25 Mar. 25 3 3/25/11 Asteroids Evidence for a violent past Mar. 25 Mar. 25 Mimas July 1994 Comet Shoemaker ­Levy 9 Cratering Moon Mercury Mars Impacts s7ll happen Mar. 25 Mar. 25 Some excep7ons to the pa\erns Geological ac7vity •  Earth is geologically ac7ve  ­ ­> few features are truly old •  Evidence for a hot past! Mar. 25 Mar. 25 4 3/25/11 Forma7on of the Moon Meteorites: Ancient clues http://www.solarviews.com/eng/meteor.htm" Mar. 25 Mar. 25 Recap •  Solar nebula, protoplanetary disk •  Building planets: planetesimals, accre7on •  Evidence for a violent past Mar. 25 Mar. 25 5 ...
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This note was uploaded on 01/19/2012 for the course ASTRO 109750 taught by Professor Keeting during the Fall '11 term at Rutgers.

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