Visiting the Observatory The Planets of our Solar System

Telescopes For Observing The Planets

Our solar system consists of an average star we know as the Sun, and nine planets. The Sun is the strongest source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun's nearest known neighbor is a red dwarf star called Proxima Centauri, some 4.3 light years away.

	Mercury the closest planet to the sun, was named by the Romans after the fleet-footed messenger of the gods because it seemed to move more quickly than any other planet. Most of the scientific findings about Mercury comes from the Mariner 10 spacecraft which was launched on November 3, 1973. It flew past the planet on March 29, 1974 at a distance of 705 kilometers from the surface.
	Venus, the second planet, is named after the Roman goddess of love and beauty, and is veiled by thick swirling cloud cover. Venus rotates from east to west. To an observer on Venus, the Sun would rise in the west and set in the east. A Venusian day is 243 Earth days and is longer than its year of 225 days! At least 85% of the Venusian surface is covered with volcanic rock. Huge lava flows, extending for hundreds of kilometers, have flooded the lowlands creating vast plains.
	Earth, the third planet from the sun, orbits at a mean distance from the sun of 92,960,000 miles. that distance is also known as 1 Astronomical Unit. (AU) Large distances between planets are measured using AU's. The average temperature on our planet is 59° F (15° C) and the diameter of the earth is 7,926 miles. Our atmosphere is mainly a nitrogen oxygen mixture which gives earth it's blue color.
	Mars is the fourth planet from the Sun and the seventh largest. Mars (Greek: Ares) is the god of War. The planet probably got this name due to its red color. The Roman god Mars was a god of agriculture before becoming associated with the Greek Ares. Though Mars is much smaller than Earth, its surface area is about the same as the land surface area of Earth. Mars has been thought to be the most favorable place in the Solar System (other than Earth!) for human habitation. It appears that there may be liquid water on Mars.
	Jupiter "The Bringer of Jollity" is the fifth planet from the Sun and by far the largest. Jupiter is more than twice as massive as all the other planets combined. Jupiter was first visited by Pioneer 10 in 1973. The planet is about 90% hydrogen and 10% helium and probably has a core of rocky material amounting to something like 10 to 15 Earth-masses. The vivid colors seen in Jupiter's clouds are probably the result of subtle chemical reactions of the trace elements in Jupiter's atmosphere, perhaps involving sulfur whose compounds take on a wide variety of colors, but the details are unknown.
	Saturn is the sixth planet from the Sun and is the second largest in the solar system with an equatorial diameter of 74,130 miles. Saturn is visibly flattened at the poles, a result of the very fast rotation of the planet on its axis. Its day is 10 hours, 39 minutes long, and it takes 29.5 Earth years to revolve about the Sun. The atmosphere is primarily composed of hydrogen with small amounts of helium and methane simular to Jupiters. Saturn's ring system makes the planet one of the most beautiful objects in the solar system. Space probes have shown that the main rings are really made up of a large number of narrow ringlets. The origin of the rings is not well understood.
	The seventh planet from the Sun is Uranus "The Magician". Uranus is larger in diameter but smaller in mass than Neptune. Uranus is composed primarily of rock and various ices. The blue color is the result of absorption of red light by methane in the upper atmosphere. There may be colored bands like Jupiter's but they are hidden from view by the overlaying methane layer. Uranus' magnetic field is odd in that it is not centered on the center of the planet and is tilted almost 60 degrees with respect to the axis of rotation. Uranus is sometimes just barely visible with the unaided eye on a very clear night; it is fairly easy to spot with binoculars. A small astronomical telescope will show a disk.
	Neptune "The Mystic" is the eighth planet from the Sun and the fourth largest. It is smaller in diameter but larger in mass than Uranus. Neptune's composition is probably similar to Uranus': various "ices" and rock with about 15% hydrogen and a little helium. The blue color is largely the result of absorption of red light by methane in the atmosphere but there is some additional as-yet-unidentified chromophore which gives the clouds their rich blue tint. Neptune also has rings Like Uranus and Jupiter, Neptune's rings are very dark but their composition is unknown. Neptune's magnetic field is, like Uranus', oddly oriented and probably generated by motions of conductive material (probably water) in its middle layers. If you know exactly where to look you can see Neptune with with binoculars, but a large telescope is needed to see anything other than a tiny disk.
	Pluto the tiny planet. Pluto is smaller than seven of the solar system's moons. Some say Pluto would be better classified as a large asteroid or comet rather than a planet. In Roman mythology, Pluto is the god of the underworld. It received this name perhaps because it's so far from the Sun that it is in perpetual darkness. Pluto was discovered in 1930 by accident and is the only planet that has not been visited by a spacecraft. Pluto can be seen with an amateur telescope but it is not an easy thing to do.