Lec23-Apr12 - 4/12/11 Quiz [email protected] #1 Jupiter’s...

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Unformatted text preview: 4/12/11 Quiz [email protected] #1 Jupiter’s interior contains a large [email protected] of ______, which can conduct electricity. Astro 109 Lecture 23: Jovian Planets and Moons April 12 A.  B.  C.  D.  E.  iron carbon molecular hydrogen metallic hydrogen metallic nitrogen Apr. 12 Quiz [email protected] #2 What shape are moons? A.  B.  C.  D.  All moons are spherical. Large moons are spherical, and small ones are irregular. Small moons are spherical, and large ones are irregular. The moons of Earth and Jupiter are spherical, while the moons of Uranus and Neptune are not. Key Concepts •  Jovian planets: shape, structure •  planet/moon and moon/moon [email protected] •  ice geology •  each moon has a unique story Apr. 12 Apr. 12 Shape: Jupiter Apr. 12 Apr. 12 1 4/12/11 Shape: Saturn Interior Apr. 12 Apr. 12 Atmospheres Apr. 12 Apr. 12 Discussion [email protected] [email protected] fields Why does Jupiter have several [email protected] cloud layers? A.  Different layers contain clouds made of gases that condense at different temperatures. B.  Each layer represents a [email protected] region where the temperature is cool enough for water to condense. C.  Different gases are present at different [email protected] in Jupiter’s atmosphere. D.  Wind prevents clouds from forming at many [email protected], so we only see clouds at [email protected] with liZle wind. Apr. 12 Apr. 12 hZp://www.nasa.gov/mission_pages/hubble/news/jupiter_flyby.html hZp://www.universetoday.com/74376/cassini ­flies ­through ­saturns ­aurora/ 2 4/12/11 Jupiter’s Galilean Moons Apr. 12 Apr. 12 Discussion [email protected] What do the [email protected] suggest about the [email protected] of Ganymede and Callisto? They are a mixture of rock and iron. They are solid iron. They are mostly methane. They are mostly liquid hydrogen. They are a mixture of rock and ice. Earth’s Moon 3346 Io 3528 Europa A.  B.  C.  D.  E.  3010 Ganymede 1936 Callisto 1834 Apr. 12 Apr. 12 Visible light Apr. 12 Io Density (kg/m3) Thermal emission (false color) From Galileo Volcanoes! Apr. 12 3 4/12/11 Apr. 1997 Sept. 1997 July 1999 hZp://photojournal.jpl.nasa.gov/catalog/PIA02501 From New Horizons spacecrak (Wikipedia) Apr. 12 Apr. 12 Tidal force Discussion [email protected] The main source of energy for Io’s volcanoes is A.  B.  C.  D.  E.  heat from the Sun. heat within Io lek over from its [email protected] [email protected] decay of elements. @dal [email protected] from Jupiter. Jupiter’s [email protected] field. Apr. 12 Apr. 12 Example: Tidal force from Moon R⊕ Fnear = 6378 km = (6.67 × 10−11 N m2 /kg2 )(7.35 × 1022 kg)(1 kg) (1 km)2 × (384400 km − 6378 km)2 (103 m)2 = 3.43 × 10−5 N Ffar = (1 km)2 (6.67 × 10−11 N m2 /kg2 )(7.35 × 1022 kg)(1 kg) × (384400 km + 6378 km)2 (103 m)2 = 3.21 × 10−5 N difference Apr. 12 = 0.22 × 10−5 N Apr. 12 4 4/12/11 Effects of @dal forces •  Earth’s [email protected] is slowing down – the day is lengthening by 0.0016 seconds per century. •  The Earth raises @des on the Moon – in rocks! The Moon is [email protected] locked” so it keeps the same face toward Earth. Apr. 12 Apr. 12 Discussion [email protected] Tidal [email protected] Why is the orbit of Io around Jupiter not circular? •  elongated orbit around Jupiter  ­ ­> @dal forces vary in strength •  Io “flexes” ever 1.8 d period (effects exaggerated here) Apr. 12 hZp://www.astro.washington.edu/users/smith/Astro150/Tutorials/TidalHeat/ A.  B.  C.  D.  Jupiter’s @dal forces make the orbit elongated. Jupiter’s [email protected] field makes the orbit elongated. Forces from Io’s volcanic [email protected] affect the orbit. A resonance with Europa and Ganymede keeps Io’s orbit from becoming circular. E.  None of the above; Io’s orbit is circular. Apr. 12 Orbital resonance •  Io goes around twice while Europa goes around once •  call this a 2:1 orbit resonance •  every 3.6 days they “meet up” Wikipedia Apr. 12 •  each @me, Europa’s gravity gives Io a “kick” that keeps Io’s orbit elongated Apr. 12 5 4/12/11 Europa Apr. 12 Apr. 12 Discussion [email protected] Lineae Europa shows few signs of cratering because A.  B.  C.  D.  E.  Jupiter’s gravity deflects asteroids away from it. Jupiter’s [email protected] field deflects asteroids away from it. water fills any holes in the surface ice. it is a small moon, so few meteors hit it. lava flows cover any craters that form. (approx. true color) Apr. 12 Apr. 12 Model for Europa (enhanced color) probably 2× Earth’s oceans! Apr. 12 Apr. 12 6 4/12/11 Model for Europa Ganymede hZp:[email protected]/display.cfm?IM_ID=5543 Apr. 12 Apr. 12 Callisto Apr. 12 Apr. 12 Apr. 12 7 ...
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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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