Comparative planetology Essay Example | Topics and Well Written Essays - 1250 words

Comparative planetology - Essay Example * "Negative values of rotation period indicate that the planet rotates in the direction opposite to that in which it orbits the Sun. This is called retrograde rotation". From the above table it can be implied that retrograde rotation is followed by Venus, Uranus and Pluto in the whole solar system (Windows to the Universe, UCAR, 2000-2005). "The eccentricity (e) is a number which measures how elliptical orbits are. If e=0, the orbit is a circle. All the planets have eccentricities close to 0, so they must have orbits which are nearly circular" (Windows to the Universe, UCAR, 2000-2005). As it is obvious from the table 1 above that the number of moons varies from 0 for Mercury and Venus to 60 for Jupiter. Mercury, Venus, Earth and Mars are denser, rocky and called Terrestrial Planets in contrast to Jupiter, Saturn, Uranus and Neptune, which are less dense, gas-rich and are called Jovian Planets. Rings are present around Jupiter, Saturn, Uranus and Neptune with the exception being Pluto. No rings are present around the terrestrial planets Mercury, Venus, Earth and Mars. ... e above table it can be implied that retrograde rotation is followed by Venus, Uranus and Pluto in the whole solar system (Windows to the Universe, UCAR, 2000-2005). "The eccentricity (e) is a number which measures how elliptical orbits are. If e=0, the orbit is a circle. All the planets have eccentricities close to 0, so they must have orbits which are nearly circular" (Windows to the Universe, UCAR, 2000-2005). All the planets orbit the sun in nearly circular pattern, same direction and lie in the same plane (Bennett, J., et al., 2004, The cosmic perspective, Chapter 8.2). As it is obvious from the table 1 above that the number of moons varies from 0 for Mercury and Venus to 60 for Jupiter. Mercury, Venus, Earth and Mars are denser, rocky and called Terrestrial Planets in contrast to Jupiter, Saturn, Uranus and Neptune, which are less dense, gas-rich and are called Jovian Planets. Rings are present around Jupiter, Saturn, Uranus and Neptune with the exception being Pluto. No rings are present around the terrestrial planets Mercury, Venus, Earth and Mars. But the atmosphere ranges from none on Mercury, Carbon dioxide on Venus and Mars, Nitrogen and Oxygen on Earth, Hydrogen and Helium on Jupiter, Saturn, Uranus, Neptune and lastly Methane on Pluto (Bennett, J., et al, 2004, The cosmic perspective, Chapter 10.3). The interiors of the earth can be broadly categorized on the basis of layering by density and layering by strength. In layering by density the earth has three layers called Core, Mantle and Crust and in layering by strength of the rock. The strength of a rock depends on its composition, its temperature, and the surrounding pressure. (Bennett, J., et al, 2004, The cosmic perspective, Chapters 10.2). The inner layers of a planet by rock strength appear to be