The Titius-Bode lair predicted that there should be a planet between Mars and Jupiter about 2.8 astronomical units from the Sun. In 1800 six astronomers, with Johann Schroter as president and Baron von Zach as secretary, worked out a scheme jointly to search for this missing planet. However, before their plans could be put fully […]
Details of the SATELLITES OF URANUS and NEPTUNE . The radii of all five satellites of Uranus are too small to be measured directly, but values can be calculated from their observed brightness and an assumed albedo. If they are ice-covered, the radii could be as small as 100km (Miranda) to 350km (Titania) whereas extremely […]
In addition to the ring particles, there are ten SATELLITES of SATURN . The diameters of the satellites are difficult to measure from the Earth. Turbulence in the Earth’s atmosphere blurs the image by at least 0.1 to 0.2 arc sec. This causes an appreciable error for an object whose apparent size may be only […]
With this review of Jupiter’s satellites complete we now consider SATURN’S RINGS. When Galileo turned his telescope towards Saturn in 1610 he saw the planet in three parts. Later, in 1612, it looked quite regular and he feared that his earlier observations may have been in error. In 1614 C.Scheiner drew Saturn as a planet […]
In addition to our Moon and the two tiny satellites of Mars, a further 31 natural satellites are known in the outer Solar System. They are in orbit around the four giant planets: Mercury, Venus and Pluto have no known satellites whereas Jupiter has fourteen, Saturn has ten, Uranus five and Neptune two. Five satellites […]
The planets form the bulk of the Solar System, but many other bodies are known which, though much smaller or less massive than planets, are full of interest. These minor bodies include the glorious set of rings around Saturn, tens of planetary satellites, hundreds of comets, thousands of asteroids, countless meteors, and other small particles […]
Pluto has the largest, most eccentric and most highly-inclined orbit of any of the known planets. Because of this large eccentricity, Pluto, when near perihelion, is actually closer to the Sun than Neptune can ever be; this will next occur in 1989. The highly-inclined orbit takes Pluto as much as a billion and a quarter […]
Uranus and Neptune are difficult bodies to study. The radiation received at the Earth from Uranus is less than one-thousandth of that received from Jupiter and from Neptune it is even less. The greater distances of the two planets make surface details more difficult to detect than on either Jupiter or Saturn. No planets are […]
Beyond Jupiter is Saturn, the most distant planet that was known to the ancients. With the obvious exception of the rings, it appears to be similar to Jupiter in many ways. Saturn’s rings effectively consist of an enormous number of minute satellites and are considered, together with the ten known satellites Saturn is the least […]
In 1955, when radio astronomy was still a comparatively new science, astronomers near Washington DC were looking for previously undiscovered radio sources of small apparent size. Their telescope picked up strong waves at a frequency of 22.2MHz, corresponding to a wavelength of 13.5metres. At first they attributed these radio waves to terrestrial sources such as […]