Kuiper Belt (Pluto) LACC: §12.3, 12.4, 13.3 • Understand how the various object in the outer solar system are classified • Understand what conditions and processes shaped these objects • Know the dwarf planets: Pluto, Eris. An attempt to answer the “big questions”: what is out there? Are we alone? 1 Thursday, April 8, 2010
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Kuiper Belt (Pluto)LACC: §12.3, 12.4, 13.3
• Understand how the various object in the outer solar system are classified
• Understand what conditions and processes shaped these objects
• Know the dwarf planets: Pluto, Eris.
An attempt to answer the “big questions”: what is out there? Are we alone?
The IAU members gathered at the 2006 General Assembly agreed that a "planet" is defined as a celestial body that(a) is in orbit around the Sun(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape (c) has cleared the neighborhood around its orbit.
Little is known about Pluto's atmosphere, but it probably consists primarily of nitrogen with some carbon monoxide and methane. It is extremely tenuous, the surface pressure being only a few microbars. Pluto's atmosphere may exist as a gas only when Pluto is near its perihelion; for the majority of Pluto's long year, the atmospheric gases are frozen into ice. Near perihelion, it is likely that some of the atmosphere escapes to space perhaps even interacting with Charon. NASA mission planners want to arrive at Pluto while the atmosphere is still unfrozen.
This model system has been artificially lit and reoriented so that its equator lies in a horizontal plane. The scale of time has been altered so that 2 days of simulated time pass in 1 second of real time.
Currently, the largest known dwarf planet is (136199) Eris. Eris is just slightly larger than Pluto, but orbits as far as twice Pluto's distance from the Sun. Eris is shown above in an image taken by a 10-meter Keck Telescope from Hawaii, USA. Like Pluto, Eris has a moon, which has been officially named by the International Astronomical Union as (136199) Eris I (Dysnomia). Eris was discovered in 2003, and is likely composed of frozen water-ice and methane. Currently, the only other officially designated "dwarf planet" is (1) Ceres.
• Understand how the various object in the outer solar system are classified: Centaurs, Kuiper Belt Objects, Scattered Disk Objects
• Understand what conditions and processes shaped these objects: formed outside orbit of Neptune, near collisions throw them out of the Kuiper Belt--Centaurs, SDOs, rogue planet?
• Know the dwarf planets: Pluto (w/ Charon, Hydra, and Nix), Eris (w/ Dysnomia) is largest.
An attempt to answer the “big questions”: what is out there? Are we alone?
12Thursday, April 8, 2010
• Ch 12, pp. 286: 6.
Due at the beginning of next class period.
Test covering chapters 10-13 next class period.
Be working your Solar System project.
LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe,
3rd ed.
13Thursday, April 8, 2010
CometsLACC: §12.3, 12.4, 13.3
• Know how Meteorites are classified: composition (laboratory analysis)
• Understand under what conditions and processes the comets formed: formed outside orbit of Neptune, near collisions alter throw them out of the Kuiper Belt
• Know what Comets tell us about the conditions and processes shaped our solar system: Comets tell us about our solar system: composition and history.
...Comet SOHO-6, one of numerous sungrazing comets...as its head enters the equatorial solar wind region. It eventually plunged into the Sun. ...23 December 1996.... The field of view of this coronagraph encompasses 8.4 million kilometers (5.25 million miles) of the inner heliosphere.
Conventional wisdom is that “Comets are ... dirty snowballs or "icy mudballs". They are a mixture of ices (both water and frozen gases) and dust that for some reason didn't get incorporated into planets when the solar system was formed. This makes them very interesting as samples of the early history of the solar system.” (http://www.nineplanets.org/comets.html)
However, data from the Startdust mission “...implies that while the comets contain ices that formed at the edge of the solar system, the rocky materials that actually make up the bulk of a comet's mass actually formed in the hottest possible conditions. The inner solar system can be thought of as a factory producing rocky materials that were distributed outwards to all the bodies and regions of the solar system.” (http://stardust.jpl.nasa.gov/news/news113.html)
One of the most remarkable particles found in the Stardust collection is a particle named after the Inca Sun God Inti. Inti is collection of rock fragments that are all related in mineralogical, isotopic and chemical composition to rare components in meteorites called "Calcium Aluminum Inclusions" or CAI's for short. CAI's are the oldest materials that formed in the solar system and they contain a remarkable set of minerals that form at extremely high temperature. In addition to these same minerals, Inti also has tiny inclusions that may have been the first generation of solids to condense from hot gas in the early solar system. These include compounds of titanium, vanadium and nitrogen (TiN and VN) as well as tiny nuggets of platinum, osmium, ruthenium, tungsten and molybdenum. In certain chemical environments and at high enough temperature in the early solar system these exotic materials were the only solid materials that could survive without being vaporized.
The nucleus of Comet Halley is approximately 16x8x8 kilometers.The density of Halley's nucleus is very low: about 0.1 gm/cm3 indicating that it is probably porous, perhaps because it is largely dust remaining after the ices have sublimed away. (http://www.nineplanets.org/halley.html)
When Earth’s orbit passes through a trail of comet debris, there are many meteors visible in a single night--a meteor shower. The Earth passes through the meteoroids from the comet in the same place each year as it goes around the Sun, so meteor showers occur annually. For example, every August we can see the beautiful Perseid meteor shower, caused by the dusty trail that Comet Swift-Tuttle left behind.
• Understand what conditions and processes shaped the comets: rocky materials -- inner solar system, icy materials -- outer solar system
• Know what Comets tell us about our solar system: potentially unchanged since they formed, they reveal the early solar system’s composition and condition.
• Understand how meteor showers are related to comets: Earth passes through/near a comet’s orbit and encounters its dust.
An attempt to answer the “big questions”: what is out there? Are we alone?
29Thursday, April 8, 2010
• Ch 12, pp. 286: 4.
Due at the beginning of next class period.
Test covering chapters 10-13 next class period.
Be working your Solar System project.
LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe,
systems• Orbital properties: axial tilt (Uranus is on its side),
length of day, length of year, distance from the sun• Atmospheres: composition (H, He, etc.), clouds
(H2O, (NH4)SH, NH3, CH4) depending on the different molecules’ condensation temperatures
[10 pts] Moons of Jupiter: Io, Europa, Ganymede, Callisto, Saturn: Titan; and Neptune Triton.
• Physical and orbital properties: mass, size, composition (Europa and Ganymede may have significant water oceans under their crust), distance from their planet, Triton orbits backwards, Rhea might have rings
• Surface features: craters (esp. Callisto), volcanic activity (Io, Triton, Enceladus), what causes these moons to be geologically active (tidal forces, erupting substances may not be not lava)
• Titan’s atmosphere: composition (N2, 1.6 bars), methane (CH4) seas and rain?
(some meteorites came from the Luna, Mars, Vesta); transneptunian objects--Centaurs (between Jupiter and Neptune), Kuiper belt (50 - 100 AU, outside the orbit of Neptune), Oort Comet Cloud (random elliptical orbits out to 100,000 AU
• Composition: asteroids--C, S, and M type; meteorites--iron, stoney iron, stoney (includes carbonaceous chondrites)); comets--parts (nucleus, coma, tail (ion and dust))
• Notable: Minor Planets--Ceres, Pluto (w/ moons), Eris; Centaurs--Chiron; Ida w/ moon Dactyl; comet Shoemaker-Levy 9
[10 pts] Solar System Evolution• Ring Systems: composition (ices, rocky material),
origin (moons wander inside Roche limit, debris from meteor impacts on small moons), evolution (shepherd moons keep them tidy, orbital resonances with major moons), bright vs dark (young & icy vs old & dusty)
• Outer planet’s moons (differentiation?), KBOs, comets: icy--outside frost line
• Undifferentiated asteroids are the oldest objects known (over 4.5 billion years old); differentiated asteroids may be parts of early planetesimals; asteroids and comets are samples of the early solar system containing organic compounds like amino acids--the building blocks of life