Direct measurements of the conditions deep inside Jupiter are of course impossible. Calculations of these conditions are, however, constrained in a number of ways. The low mean density, only 1.3 times that of water, implies that the composition must be very different from the terrestrial planets with their typical mean density of live times that, […]
The apparent magnitude of Jupiter varies to some extent because of its varying distance from the Earth, but this is not sufficient to explain all the observed changes. Since 1862, the mean opposition magnitude has ranged over 0.45 magnitudes so that, at the brightest opposition, Jupiter was reflecting 50 per cent more light than at […]
The most prominent and permanent feature of the visible surface of Jupiter is the GREAT BED SPOT . It is an elongated area of variable size; at its largest,-in the 1880s, it was about 38500km long by 13800km wide and had a surface area about equal to that of the Earth. The spot lies in […]
When we look at Jupiter we see only the uppermost cloud layers in its atmosphere. The composition of the atmosphere at this level can be determined spectroscopically . The first re¬ported observations of dark absorption bands in Jupiter’s spectrum were made by Angelo Secchi in 1863. It was not until the early 1930s that the […]
Jupiter, the nearest, of the giant, planets, in also the largest and most massive. It appears brighter than any other planet apart from Venus; at times it may even cast, a shadow. Some of its surface features, and the four brightest satellites, can easily be seen in a small telescope, or even in binoculars. .Jupiter’s […]
The inner planets and their satellites, described in the previous chapter, comprise less than half of one per cent of the planetary mass in the Solar System: more than 99.5 per cent of the planetary matter is found beyond the orbit of Mars. This region includes most of the asteroids and comets, the giant planets […]
Mars has two small satellites, PHOBOS and DEIMOs, . They are irregularly shaped, very dark objects liberally covered with craters . This gives them the appearance of modestly-sized asteriods but their almost circular orbits make it unlikely that they are simply captured asteroids. Several astronomers have suggested that they are the shattered remains of an […]
Compared TO the Earth. Mars has a thin atmosphere and Venus & thick one whereas Mercury and the Moon do not have one at all. Table 10.3 lists some of the gases which we might expect to find in planetary atmospheres because they are volatile compounds of the cosmically common elements. If a planet ever […]
From measurements of radioactive decay products, it is possible to measure the age pattern of the Earth’s continents. They are found to have an ancient nucleus, at least 2.5 billion years old, onto which successively younger extensions have been welded, a process still continuing today. The growth has not been regular and in particular there […]
Owing to the thick clouds we know little of the surface of Venus. Reference has already been made to the craters observed by radar. There is a scarcity of small craters; this is to be expected because the dense atmosphere would burn up the smaller meteoroids which would otherwise produce these craters. Venus is a […]