Week 10 - Rings, Pluto, and Beyond.docx - Made by Amit...

This preview shows page 1 - 2 out of 4 pages.

Made by Amit Solomon – [email protected]Rings, Pluto, and Beyond – Week 1012.3 -TITAN AND TRITONTitan, a Moon with Atmosphere and Hydrocarbon Lakes –Titan has roughlythe same diameter, mass, and density as Callisto or Ganymede. Presumably it also has a similarcomposition—about half ice and half rock. However, Titan is unique among moons, with a thickatmosphere and lakes and rivers and falling rain. the surface density of its atmosphere is four timesgreater than that on Earth. The atmospheric pressure on this moon is 1.6 bars, higher than that on anyother moon and, remarkably, even higher than that of the terrestrial planets Mars and Earth. Theatmospheric composition is primarily nitrogen, an important way in which Titan’s atmosphereresembles Earth’s. Radar and infrared imaging of Titan from the Cassini orbiter gradually built up apicture of a remarkably active surface on this moon, complex and geologically young.Triton and Its Volcanoes –Neptune’s largest moon Triton has a diameter of 2,720 kilometerand a density of 2.1 g/cm3, indicating that it’s probably composed of about 75% rock mixed with 25%water ice. Measurements indicate that Triton’s surface has the coldest temperature of any of theworlds our robot representatives have visited. Because its reflectivity is so high (about 80%), Tritonreflects most of the solar energy that falls on it, resulting in a surface temperature between 35 and 40K. The surface material of Triton is made of frozen water, nitrogen, methane, and carbon monoxide.12.4 -PLUTO AND CHARONPluto is not a moon, but we discuss it here because its size and composition are similar to many moonsin the outer solar system. Our understanding of Pluto (and its large moon Charon) have changeddramatically as aresult of the New Horizons flyby in 2015.Is Pluto a Planet? –Pluto was discovered through a careful, systematic search, unlike Neptune,whose position was calculated from gravitational theory. Nevertheless, the history of the search forPluto began with indications that Uranus had slight departures from its predicted orbit, departures thatcould be due to the gravitation of an undiscovered “Planet X.” From the time of its discovery, it wasclear that Pluto was not a giant like the other four outer solar system planets. For a long time, it wasthought that the mass of Pluto was similar to that of Earth, so that it was classed as a fifth terrestrialplanet, somehow misplaced in the far outer reaches of the solar system. Only after the discovery of itsmoon Charon in 1978 could the mass of Pluto be measured,and it turned out to be far less than the mass of Earth. In addition to Charon, Pluto has four smallmoons.Subsequent observations of Charon showed that this moon is in a retrograde orbit and has a diameterof about 1200 kilometers, more than half the size of Pluto itself. This makes Charon the moon whosesize is the largest fraction of its parent planet. Neither Pluto’s path around the Sun nor its size

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 4 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Spring
Professor
Keeton
Tags
Cosmology, Planet, Amit Solomon

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture