Planetary satellites

Cronin J. R., PizzareUo S., and Cruikshank D. P. (1988) Organic matter in carbonaceous chondrites, planetary satellites, asteroids and comets. In Meteorites and the Early Solar System (eds. J. F. Kerridge and M. S. Matthews). University of Arizona Press, Tucson, pp. 819-857. 

Saturn s retinue of satellites is qualitatively quite different from Jupiter s fellow travelers. The system contains just one large satellite, Titan, which is virtually identical in bulk properties to Ganymede and Callisto. Titan s density, determined from Voyager observations, suggests a ice/rock composition and a probable differentiated interior by analogy with the Jupiter satellites. Titan s atmosphere, the first discovered for a planetary satellite, was detected in 1944 through identification of methane gas absorptions in its spectrum (Kuiper, 1944). 

Consolmagno G. J. and Lewis J. S. (1977) Preliminary thermal history models of icy satellites. In Planetary Satellites (ed. J. A. Burns). University of Arizona Press, Tucson, pp. 492-500. 

Prinn R. G. and Fegley B. (1989) Solar nebula chemistry origin of planetary, satellite, and commentary volatiles. In Origin and Evolution of Planetary and Satellite Atmospheres (ed. S. Atreya). University of Arizona Press, Tucson, pp. 78-136. 

Jessberger E. K., Kissel J., and Rahe J. (1989b) The composition of comets. In Origin and Evolution Planetary Satellite Atmospheres (eds. J. B. Pollack, M. S. Matthews, and S. K. Atreya). University of Arizona Press, Tucson, AZ, pp. 167-191. 

Shepherd satellite—planetary satellite whose gravitational perturbations on a particle tend to keep it in a stable orbit around the planet. The Pascal (Pa) is the metric unit of pressure (force per unit area). One Pascal is defined as a pressure of one Newton per square meter. The standard sea level atmospheric pressure on Earth is 101,200 Pascals. 

The orbits of double stars, where the sizes of the orbits have been determined, provide the only information we have about the masses of stars other than the Sun. Close doublestars will become decidedly non-spherical because of tidal distortion and/or rapid rotation, which produces effects analogous to those described above for close artificial planetary satellites. Also, such stars often have gas streaming from their tidal and equatorial bulges, which can transfer mass from one star to the other, or can even eject it completely out of the system. Such effects are suspected to be present in close doublestars where their period of revolution is found to be changing. 

There is a poor knowledge of the initial structure of cold ice deposited under vacuum, and, with greater reason, after exposure to radiations. Such cold ice is a dominant component in several astrophysical environments (comets, planetary satellites, and interstellar grains) and its properties are important for the understanding of processes such as molecule formation in the interstellar space and comet outgassing. 

Today astronomers routinely study the chemical composition of a planet by analyzing sunlight reflected off its surface and atmosphere. The same method is used to analyze the chemical composition of other bodies in the solar system, such as comets, meteors, and planetary satellites. This process is challenging since, in some cases, relatively modest amounts of light are reflected from a planet or other body. Also, the spectrum observed is likely to be very complex, with the lines of many elements and compounds present in the pattern. 

These space-based observatories and a number of terrestrial observatories have produced a growing body of data about five of the planets in the solar system—Mercury, Venus, Mars, Jupiter, and Saturn—as well as numerous other bodies, including comets, asteroids, and many planetary satellites, including our own Moon. 

At the time, more than a dozen planetary satellites had already been discovered for Jupiter, Saturn, Uranus, and Neptune. None had been found for Venus or Mercury, nor were they likely to be found, given the proximity of these planets to the Sun. Mars likewise had no satellites. .. or, at least, none that had yet been discovered. 

In this chapter we overview (1) the progress in telescopic and spacecraft observations of the opposition effects of some atmosphereless celestial bodies and (2) the problems in understanding the photometric and polarimetric properties of planetary regoliths at small phase angles. Since several reviews of photometric and polarimetric observations of the Moon, Mars, asteroids, and planetary satellites have been published [34-36], we focus on findings related predominantly to imaging photometry and polarimetiy of planetary surfaces with spacecraft and telescopic techniques. We consider also recent results concerning photometric and polarimetric observations of minor planets. 

Saturn s moon Titan is the only planetary satellite in the solar system with an atmosphere. Ethane is present in Titan s atmosphere along with the two major components nitrogen and methane. 

Morrison, D. 1976a, in Planetary Satellites, ed. J.A. Burns, Univ. 

Long before spacecraft encounters, celestial mechanics had been employed to determine the masses of those planets that possess moons. With the exceptions of Mercury and Venus, for which the arguments were more indirect, the masses of all the planets are now known from satellite observations. Detailed examination of the periodicities of their moons also reveals that they interact through resonant orbits, which causes the structuring of the radial distribution of the planetary satellite systems. Detailed observations of satellite motion also permit the determination of internal mass distribution and oblateness for most of the planets. These determinations have been augmented for the outer planets by direct flybys with the Voyager 1 and 2 spacecraft. Finally, mutual phenomena of the moons of several of the major planets provide the determination of satellite masses through the solution of the motion under mutual perturbations for the satellite systems. 

Binary Stars Chaos Cosmology Gravitational Wave Astronomy Mechanics, Classical Moon (Astronomy) Perturbation Theory Planetary Satellites (Natural) Relativity, General Solar Physics Solar System, General Stellar Structure and Evolution... 

Cosmic Radiation Galactic Structure and Evolution Infrared Spectroscopy Interstellar Matter Planetary Satellites, Natural Solar System, General Stellar Spectroscopy Stellar Structure and Evolution Ultraviolet Space Astronomy... 

In 1930, Tombaugh discovered Pluto, the outermost known planet (Reaves, 1997 Marcialis, 1997). Several authors have derived the radius of Pluto with very small uncertainties unfortunately, the derived values do not overlap. Consequently, only a broad range can be quoted (1145 to 1200 km) within which the true radius of Pluto may fall (Tholen Buie, 1997). Pluto is by far the smallest planet of our Solar System it is even smaller than many planetary satellites. Pluto s orbit is highly eccentric and inclined by more than 17° to the ecliptic plane (Malhotra Williams, 1997). At perihelion (29.7 AU), Pluto is closer to the Sun than Neptune (30.1 AU), and at aphelion it reaches a heliocentric distance of almost 50 AU. Pluto s orbital period, 248.35 sidereal years, is locked in a 3 2 ratio with that of Neptune (Cohen Hubbard, 1965). The axis of rotation is nearly in the orbital plane therefore, this small planet undergoes rather complex seasonal changes (Spencer et al., 1997). Malhotra (1993, 1999) provides interesting discussions of the possible evolution of Pluto s orbit and that of other planets (see also Stem etai, 1997). 

---