Pluto, atmosphere

Alkanes have the general molecular formula C H2 +2 The srmplest one methane (CH4) rs also the most abundant Large amounts are present rn our atmosphere rn the ground and rn the oceans Methane has been found on Juprter Saturn Uranus Neptune and Pluto and even on Halley s Comet... 

Diacetylene (HC=C—C=CH) has been identified as a component of the hydrocarbon rich atmospheres of Uranus Neptune and Pluto It is also present m the atmospheres of Titan and Triton satellites of Saturn and Neptune respectively... 

Pluto, with a diameter of 2300 km, has now been demoted from the smallest planet to one of the largest Kuiper belt objects. Pluto and its satellite Charon could be considered a binary system because they are closer in size than any other known celestial pair in the solar system and the barycenter of their orbits does not lie within either body. There are also two smaller moons, Nix and Hydra. All four bodies are likely KBOs with similar compositions. Pluto has a thin atmosphere containing N2, with minor CH4, CO, and Ar. Curiously, the face of Pluto oriented towards Charon contains more methane ice, and the opposite face contains more nitrogen and carbon monoxide ice. 

The chemical dynamics, reactivity, and stability of carbon-centered radicals play an important role in understanding the formation of polycyclic aromatic hydrocarbons (PAHs), their hydrogen-dehcient precursor molecules, and carbonaceous nanostructures from the bottom up in extreme environments. These range from high-temperature combustion flames (up to a few 1000 K) and chemical vapor deposition of diamonds to more exotic, extraterrestrial settings such as low-temperature (30-200 K), hydrocarbon-rich atmospheres of planets and their moons such as Jupiter, Saturn, Uranus, Neptune, Pluto, and Titan, as well as cold molecular clouds holding temperatures as low as 10... 

Neptune s large satellite Triton, which has a very thin nitrogen atmosphere with clouds, plumes, and haze, an extremely cold surface with nitrogen, methane, carbon monoxide, and carbon dioxide ices which interact with the atmosphere, and a fairly high mean density, make it seem more like Pluto than the other satellites of Neptune and those of Saturn and Uranus. Not enough is known about Pluto to explore these similarities this probably awaits future missions to Pluto, especially the New Horizons mission that NASA hopes to launch in 2006. 

Neptune clockwise instead of counterclockwise (direct motion). If c ie views the solar system from above the Sun s north pole, all the planets have diiect (counterclockwise) revolutions around the Sun, and most of them have direct rotations the exceptions are Venus, Uranus, and possibly Pluto. Infrared (at wavelei lhs loi r than those of red light) observations of Triton since 1980 indicated the presence of an atmosphere containing methane, and the presence of nitrogjen in solid or liquid form on its surface. However, its size and mass remained poorly known. 

Pluto, the smallest of the Sun s planets and the farthest, on average, from the Sun, is shown with its moon Charon. Methane has been found in the thin atmosphere of Pluto. 

C4H2 isomers are of great interest to astronomers because some of these molecules occur in the atmospheres of Titan [74] (and references therein), Jupiter [75] (and references therein), possibly Pluto [76] in a comet [77], and in circumstellar and interstellar media [42,78-80]. Quantum chemical treatments of the 18 possible constructs, which included branched open constructs, produced 10 molecules of which four were open and six were cyclical. All have singlet ground states. Several investigators have synthesized 4Ol(s) in the gas phase and in solvents. Goldberg et al. [81] have synthesized 4O2(s) in the gas phase. 

For the present, knowledge of these two bodies is still somewhat limited and speculative. Earth-based observations and data provided by orbiting telescopes indicate that Pluto s atmosphere is very thin, with a pressure on the planet s surface of between three and 50 microbars (0.3-5 percent that of Earth s atmosphere). The maximum temperature observed in the upper atmosphere is 106 K (—167°C), and the most abundant gases present are expected to be nitrogen, methane, carbon monoxide, and species produced by the photolysis of these substances. 

Researchers have learned a vast amount of new information about Jupiter, Saturn, Uranus, Neptune, Pluto and the Kuiper Belt Objects in the last century. Improved terrestrial telescopes, the Hubble Space Telescope, and space explorations such as Voyager 1 and 2, Galileo, and Cassini have produced new data that will take astrochemists years to analyze and interpret, providing them with even more detailed information about the chemical composition of the atmospheres, satellites, surfaces, and other features of the outer planets and their associated bodies. 

Pluto -- considered the smallest planet in the solar system. Pluto s atmosphere probably contains methane, ammonia, and frozen water. Pluto has 1 satellite. Pluto revolves around the sun every 250 years. Pluto was named after the Roman god of the underworld. 

As to the refractory elements molybdenum and ruthenium, the oxides RUO4 and M0O2 are much more volatile than the elements, so that significant release was only observed at 2700 K in a steam atmosphere. The measured releases of the actinide elements were low and primarily in the form of aerosols. At 2300 K in steam, 0.026% of the uranium was collected outside the furnace at 2700 K in steam the release from the furnace amounted to 0.69%. Fractional releases of pluto-... 

The next major breakthrough came in the 1950 s with the development of rocket technology and spacecraft design. For the first time, scientists were able to extend their observations beyond Earth s atmosphere and send instruments to the Moon and to various planets. By 1989, all the gas giant planets had been visited by spacecraft, leaving only Pluto as an unexplored world. In addition to gathering an enormous amount of data on each of these planets, the... 

Uranus and Neptune, are large, massive bodies, distant from the Sun, with atmospheres composed mostly of hydrogen and helium. The remaining planets Mercury and Pluto are small bodies. Mercury orbits close to the sun and has a tenuous atmosphere In which atomic sodium and potassium have been seen. Pluto lies at a great distance from the Sun and Its surface Is frozen. It may have an atmosphere containing methane, similar perhaps to those of the satellites Titan of Saturn and Triton of Neptune, which have atmospheres of nitrogen with an admixture of methane. 

The planet Pluto as well as many satellites in the outer Solar System, such as Charon, Triton, and others belong to the group of relatively small objects with significant amounts of ices on the surface (see also Schmitt et al, 1998). The atmospheric surface pressure is then controlled by the surface temperature, the vapor pressure of the frozen volatiles, and the escape rate of the gases. Even Mars, with its CO2 polar caps, may be included in this group. Pluto and Charon are discussed together with comets and asteroids in Chapter 7. 

A 1987 stellar occultation by Charon did not reveal an atmosphere, but it did provide a fairly good estimate of the diameter of this satellite. Stellar occultations of small objects are rare. Fortunately, in 1988 Pluto occulted a star and the light curve was observed from a number of ground-based telescopes and from the air-bome Kuiper observatory (Millis et al., 1993). Clear evidence of a tenuous atmosphere as well as fairly good estimates of the diameter were obtained. Another fortunate event was the alignment of Charon s orbital plane as seen from Earth. In 1988, that plane could be observed edge on and, consequently, Charon passed directly in front of Pluto and disappeared completely behind it. This orientation helped in the determination of the radii and in the separation of the spectra of both objects (Binzel Hubbard, 1997). 

Lunine, J. L, Atreya, S. K., Pollack, J. B. (1989). Present state and chemical evolution of the atmospheres of Titan, Triton, and Pluto. In Origin and Evolution of Planetary and Satellite Atmospheres, 605-65, ed. S. K. Atreya, J. B. Pollack, M. S. Matthews. Tucson University of Arizona Press. 

Spencer, J. R., Stansberry, J. A., Trafton, L. M., Young, E. F. (1997). Volatile transport, seasonal cycles, and atmospheric dynamics on Pluto. In Pluto and Charon, 435-74, ed. S. A. Stern D. J. Tholen. Tucson University of Arizona Press. 

The theories of radiative transfer, molecular spectroscopy, and atmospheric physics are first combined to show how it is possible to calculate the infrared spectra of model planetary atmospheres. Next the authors describe the instrumental techniques, in order to assess the effect of real instruments on the measurement of the emerging radiation field. Finally, techniques that allow the retrieval of atmospheric and surface parameters from observations are examined. There are plenty of examples from ground-based and space observations that demonstrate the methods of finding temperatures, gas compositions, and certain parameters of the solid surface. All planets from Mercury to Pluto, many of their satellites, asteroids, and comets are discussed. 

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