to my web pages
Click here to learn about planets
Click here to go to a page about madison square garden
U rBack to topanus2
After the discovery of Uranus, it was noticed that its orbit was
not as it should be in accordance with Newton's laws. It was
therefore predicted that another more distant planet must be perturbing Uranus' orbit. Neptune was first
observed by Galle and d'Arrest on 1846 Sept 23 very near to the locations independently predicted by
Adams and Le Verrier from calculations based on the observed positions of Jupiter, Saturn and Uranus.
An international dispute arose between the English and French (though not, apparently between Adams
and Le Verrier personally) over priority and the right to name the new planet; they are now jointly credited
with Neptune's discovery. Subsequent observations have shown that the orbits calculated by Adams and
Le Verrier diverge from Neptune's actual orbit fairly quickly. Had the search for the planet taken place a few years earlier or
later it would not have been found anywhere near the predicted location.
jupiter2 BA Back to top
Jupiter is the fourth brightest object in the sky (after the Sun, the Moon and
Venus; at some times Mars is also brighter). It
has been known since prehistoric times. Galileo's discovery, in 1610, of Jupiter's four large moons Io, Europa, Ganymede and
Callisto (now known as the Galilean moons) was the first discovery of a center of motion not apparently centered on the
Earth. It was a major point in favor of Copernicus's heliocentric theory of the motions of the planets; Galileo's outspoken
support of the Copernican theory got him arrested by the Inquisition. He was forced to recant his beliefs and was imprisone
Back to topsaturn2
Saturn has been known since prehistoric times. Galileo was the first to observe
it with a telescope in 1610; he noted its odd
appearance but was confused by it. Early observations of Saturn were complicated by the fact that the Earth passes through the
plane of Saturn's rings every few years as Saturn moves in its orbit. A low resolution image of Saturn therefore changes
drastically. It was not until 1659 that Christiaan Huygens correctly inferred the geometry of the rings. Saturn's rings remained
unique in the known solar system until 1977 when very faint rings were discovered around Uranus and shortly thereafter around
Jupiter and Neptune).
earth 2Back to top
Earth is the
only planet whose English name does not derive from Greek/Roman mythology. The name
derives from Old
English and Germanic. There are, of course, hundreds of other names for the planet in other languages. In Roman Mythology,
the goddess of the Earth was Tellus - the fertile soil (Greek: Gaia, terra mater - Mother Earth).
venu s2Back to top
Venus has been
known since prehistoric times. It is the brightest object in the sky except for the Sun
and the Moon. Like
Mercury, it was popularly thought to be two separate bodies: Eosphorus as the morning star and Hesperus as the evening
star, but the Greek astronomers knew better.
Mercurymercur yBack to top
been known since at least the time of the Sumerians (3rd millennium BC). It was given two
names by the
Greeks: Apollo for its apparition as a morning star and Hermes as an evening star. Greek astronomers knew, however, that the
two names referred to the same body. Heraclitus even believed that Mercury and Venus orbit the Sun, not the Earth.
S un2Back to top
The outer layers of the Sun exhibit differential rotation: at the
equator the surface rotates once every 25.4 days; near the
poles it's as much as 36 days. This odd behavior is due to the fact that the Sun is not a solid body like the Earth. Similar effects
are seen in the gas planets. The differential rotation extends considerably down into the interior of the Sun but core of the Sun
rotates as a solid body.
mars 2Back to top
Ares) is the god of War. The planet probably got this name due to its red color; Mars is
to as the Red Planet. (An interesting side note: the Roman god Mars was a god of agriculture before becoming associated with
the Greek Ares; those in favor of colonizing and terraforming Mars may prefer this symbolism.) The name of the month March
derives from Mars.
neptune2 Back to top
is probably similar to Uranus': various "ices" and rock with about 15% hydrogen
and a little helium.
Like Uranus, but unlike Jupiter and Saturn, it may not have a distinct internal layering but rather to be more or less uniform in
composition. But there is most likely a small core (about the mass of the Earth) of rocky material. Its atmosphere is mostly
hydrogen and helium with a small amount of methane.