The Solar System can be divided into two planetary divisions. Divided based upon the distance from the Sun and physical characteristics, the inner planets are termed terrestrial while the outer are respectively termed Jovian planets.
Similar to the morphology of Earth, the terrestrial planets include Mercury, Venus, Earth, Moon and Mars.
Characteristically, the inner planets share comparable sizes, densities, and structures. The composition of these worlds is rocky in nature with high boiling points. Originating from a concentration of hydrogen and helium gas and dust, the Solar System with terrestrial planets emerged.
Further, the light compounds that formed the terrestrial planets soon vaporized by their close proximity to the Sun’s heat.
Between the orbits of Mars and Jupiter float numerous celestial bodies: the asteroids.
Coincidentally, the Jovian planets retained the lighter and colder gases within their compositions because of their distance.
Moreover, the Jovian planets seem far more massive than the closer planets and are able to hold hydrogen, water, ammonia, and methane within their icy atmospheres.
The Jovian planets are Jupiter, Saturn, Uranus, Neptune and Pluto.
Outside Pluto's orbit the comets reside. Every year we see them when a couple move close to the Earth
The closest planet to the Sun with a mean distance of 58 million kilometers. Revolving around the Sun every 88 days and rotating around its own axis every 56 Earth days, Mercury has only recently begun to be studied thoroughly.
Counter to the planet's name, based upon theoretical evidence, Mercury probably would contain iron and nickel.
Caused by deviating temperatures, Mercury's surface is covered with a layer of reddish iron dust. These metals, combined from the solar particles of the Sun, thus contribute to Mercury's high density compared to Mars, Venus, and the Earth.
The enormous range in temperatures cause erosion of exposed rock, which contributes to the layer of dust, which cloaks the surface. Deviating from a boiling 430 degrees Celcius during the day and -180 degrees Celcius during the planet's night cycle, Mercury does not follow expectations.
The second closest planet to the sun, Venus shines its bright glow as the morning star.
Covered by layers of sweeping clouds that rise up to 60 km above the planet's surface, which contain droplets of sulfuric acid, only recently have infrared detectors been able to scan through the opaque view. Openings, however, show a view of a world underneath at Venus' north and south poles.
The atmospheric pressure is only one tenth of that on Earth and a surface pressure of 96 bars. Clouded, Venus maintains a constant planetary surface temperature of 459 degrees Celcius, independent of day or night. Filtering the sun's light energy, Venus' clouds promote a continual deep freeze throughout the planet.
Ninety-seven percent of Venus' atmosphere is composed of carbon dioxide, compared Earth's seventy-eight percent nitrogen composition. Continuing, since Venus is closer to the Sun it experienced a runaway green-house effect that caused the primitive oceans to evaporate into the clouds.
That it teems with life makes Earth a precious oddity among the planets-although just how off, scientists cannot say. Certainly the conditions that made life possible were sensitive to the planet's surface temperature and therefore to its distance from the sun.
Abundant liquid water was critical to the planet's evolution. This water moderated temperatures, eroded rocks, dissolved minerals and supported complex chemical reactions, some of which yielded single-celled life close to four billion years ago. Macroscopic animals started proliferating only around 600 million years ago, eons after photosynthesis enriched the atmosphere with oxygen.
Earth's large moon probably formed from the debris after a collision between early Earth and another huge body. Because the moon and sun appear the same size from Earth, or planet is the only one to witness the beauty of the sun's corona during a total eclipse.
A lthough most known planets have many moons or satellites, the Earth’s own Moon has been studied in the most detail with his close proximity. The Moon is one-fourth the size of Earth and so the pull of gravity on the lunar surface is approximately one-sixth of that on Earth.
Recent expeditions, mainly by the satellite Clementine have led to the discovery of a frozen ice formations at the poles of the Moon; however, the Moon does not have free water nor an atmosphere, which causes a static state of weather.
Revolving about the Earth approximately every 27 days, the Moon is 384,403 km (238,857 mi).
While the origin of our companion Moon remains in debate, the most probably theory of formation is the planetesimal impact. Stated within this theory is that the Moon originally grew from the dust particles of an original nebulae that formed the Earth and the rest of the Solar System.
As the Earth had begun its first rotations, the Moon spun off and because of its smaller mass, it was grabbed by gravitation into eternal revolution about the Earth. This theory has been repeatedly been proven by the similarity between the densities of the Earth’s upper crust rocks and Moon rocks.
Still, with NASA budget cuts, missions to our closest neighbor have become rare, leaving many Moon colonization plans to be canceled.
The fourth planet from the Sun (227,940,000 km), Mars is our solar systems Red Planet.
With recent explorations to the planet by the Mars Global Surveyor and the Mars Pathfinder missions, a portal has been opened to a planet that could possibly sustain primitive live Martians.
Temperatures on the Martian surface range widely from -135 degrees C to 27 degrees C during winter at the ice capped poles. The poles, containing bright crystallized ice are composed of solid carbon dioxide or dry ice. Since, missions to Mars have begun to transform into a scientific reality, the Martian landscape had to be thoroughly examined for possible landing sites. Although a possible ancient living ground, the Martian surface still holds expanses of plains, ridges, and rift valleys.
| Olympus Mons | The largest known mountain in the Solar System at a height of 24 km and a base of more than 500 km in diameter |
| Tharsis | A huge extension of the surface that is approximately 4000 km across and about 10 km high |
| Valles Marineris | A group of canyons and craters that span 4000 km long of the planet's surface |
| Hellas Planitia | An exaan impact crater in the southern hemisphere over 6 km deep and 2000 km in diameter |
Mars has a very thin atmosphere composed of carbon dioxide (95.3%), nitrogen (2.7%), argon (1.6%) with traces of oxygen (0.15%) and water (0.03%).
The pressure on the surface is only one percent of that of Earth's, but the pressure varies greatly throughout the Martian landscape. Mars is closely orbited by two tiny satellites: Phobos and Deimos.
The fifth planet orbiting the sun at a distance 5.2 times the distance of Earth to the Sun, Jupiter forms a planetary system within itself. Scientifically believed to have almost evolved into a star, Jupiter still holds nuclear processes within, proving indications that Jupiter is a true planet.
With a rotation speed of 90,000 km/hr, Jupiter rotates around its axis in only 9 hours and 50 Earth minutes. Spinning at such an incredible pace, Jupiter forms visible dark and light belts of clouds.
Underneath these clouds, exists no physical surface without a true solid body-only liquid and breaks of solidity. The majority of Jupiter is composed of liquid hydrogen and helium that form a swirling of the phases of matter at a temperature of 30000 degrees Celcius at a pressure 30 million times that of Earth.
An example of Jupiter's surface structure is the Great Red Spot. Existing for at least 3 centuries, the Red Spot swirls as a gigantic oval in Jupiter's southern hemisphere. Rotating within itself, the Great Red Spot, swirls with a size greater than Earth every 12 days.
Phenomenally, Jupiter liquid core shrinks at a rate of 1mm per year.
Jupiter's own system of satellites, currently are numbered to contain 14. Jupiter's personal solar system grew from dust particles that formed near the Sun and others from the close asteroid belt, which got drawn to the giant planet by gravity.
The inner five: Amalthea, Io, Europa, Ganymede, and Callisto are bright stars on Earth's horizon and are of the most value to space exploration.
| Almathea. | A small satellite estimated at 160km diameter, with an extremely red surface. |
| Io. | Approximately 3640km in diameter, the satellite is slightly larger than our Moon. Active volcanoes eject sulfurous fumes. As Io orbits Jupiter, it carries round with it a cloud of gas that simulates a primitive atmosphere. |
| Europa. | is considerably smaller than Io, measuring 3060km diameter. It is not known to possess an atmosphere. Its surface appears to be completely by water ice with possible indications of life from the Jet Propulsion Laboratory's Galileo mission. |
| Ganymede. | Jupiter's largest known orbiting satellite. |
Saturn's rings make it one of the most familiar, and spectacular images of astronomy, not to mention science fiction. When Galileo trained a primitive telescope on the planet for the first time in 1610, he was misled. From the poorly resolved image in his viewfinder, he believed Saturn to be a triple-system, with a large body in the center and smaller ones on each side.
The rings may be much younger than the planet itself, and great mathematicians have found them worthy of contemplation. Laplace and James Clerk Maxwell calculated that Saturn's rings must consist of many smaller objects.
Although the planet is almost the size of Jupiter, its mass is but one third as great, giving Saturn the lowest mean density of any solar system object.
As a gas giant, the planet has no single rotation period but rather a variety depending on latitude. Upper atmosphere clouds travel around the equator in as little as 10 hours and 10 minutes; clouds in high latitudes may take half and hour longer to pass across the planet.
Based on gravitational field data, Saturn appears to have a solid core with a mass equivalent to up to 20 Earths. As the most oblate planet, the pull of gravity at its equator is less than three quarters of that at the poles.
The seventh planet from the Sun's corona, Uranus orbits as a seemingly desolate blue-green disk on the Solar System's horizon.
Revolving about the Sun every 85 Earth years and 17 hours about its 98 degree axis, Uranus probably had formed during a collision at the edges of the solar system.
Further, strangely, Uranus rotates about its steep axis opposite to that of Earth's. As with most of the distant planets in the solar system, Uranus also has a magnificent system of rings and moons that accompany its rotations. Currently, the Voyager mission has discovered 15 moons and 11 rings that hover about the blue planet.
Neptune, fourth largest of the planets in the solar system, and eighth major planet in order of increasing distance from the sun. The mean distance of Neptune from the sun is 4.5 billion km, and its mean linear diameter is approximately 49,400 km, or about 3.8 times that of the earth.
Its volume is about 72 times, its mass 17 times, and its mean density 0.31 that of the earth. The period of rotation is about 16 hr, and the period of revolution about the sun is 164.79 earth years. The average stellar magnitude of the planet is 7.8, and it is therefore never visible to the naked eye, but it can be observed in a small telescope as a small, round, greenish-blue disk without definite surface markings.
The temperature of the surface of Neptune is about -218 degrees C , much like Uranus, which is more than 1 billion miles closer to the sun. Scientists assume, therefore, that Neptune must have some internal heat source. The atmosphere consists mostly of hydrogen and helium, but the presence of up to three percent methane gives the planet its striking blue color.
Eight known satellites orbit Neptune, two of which are observable from earth. The largest and brightest is Triton, discovered in 1846, the same year Neptune was first observed. Triton, with a diameter of 2705 km, is only slightly smaller than earth's moon. It has a retrograde orbit-that is, opposite its primary's direction of rotation-unlike any other major satellite in the solar system. Despite its extreme coldness, Triton has a nitrogen atmosphere with some methane and some form of haze, and it displays an active surface of geysers that spout an unknown subsurface material.
Nereid, the second satellite, has a diameter of only about 320 km. Neptune is also circled by five thin rings. Further, its magnetic field is tilted more than 50 degrees to the rotation axis.
The most distant ninth planet from the Sun, Pluto appears as 1000 times fainter than its neighbor-planet Neptune. Although no space probes, have actually done extensive research on the planet, many astrophysicists have determined that Pluto rotates around its axis every 6 days and 9 hours and has one insignificant moon named Charon.
Hypothetically, Pluto, may have emerged into a planetary formation from a wayward satellite from the outer asteroid belt. Although, Pluto may actually not be considered as the true final planet in our Solar System, currently, most astronomers concur that Pluto should be the final significant planet within the Solar System. Some however think that Pluto might not even be a real planet, but a icelump which has accidently gotten the name 'planet'.
Further, as scientists begin to delve into the mysterious layers of Pluto, they have begun to realize that Pluto may actually lack a true atmosphere. With an average temperature below -230 degrees C, the gaseous state of the atmosphere would freeze into a liquid or solid. Pluto itself may not even be a planet but a big ice-lump!
Although much still needs to be found out about our final planet, Pluto still has begun to send answers to questioning scientists. Pluto most surely will hold a world of wonder within its core.
Calippusyclus
A cyclus used by the Greeks in their timesystem which was based on the movement of the moon and the sun, it lasts 76 years or 940 lunations, this is 27759 days. The cyclus started 330 B.C. and was used by astronomers for two centuries.
Callisto
Satelite (moon) of the planet Jupiter.
Catastrophetheory
Theory that says that during the geological past of earth, life was periodicaly distroyed by large, global catastrophies (earthquakes, vulcanic eruptions, floods) to return in a different form.
Cepheides
Name for two totally different groups of object: a. a at 15 november occuring meteorswarm in the sign of the zodiac Cepheus b. a class of pulsing changing stars named after 5 Cephei, the prototype of the Cepheis.
Ceres
One of the brightest planetoids, the first to be discovered ( by Piazzi at Palermo at 1 jan. 1801).
Chandler, period of
The period with which the rotation of the earth is counterclockwise around Earths axis.
Chandrasekharlimit
Named after S. Chandrasekhar, the maximum mass for white dwarfs. When the mass becomes larger then this critical mass (approx. 1,4 solarmasses), the star will colapse into a neutronstar or a black hole due to the fact that there can't be a hydrostatic balance.
Chiron
A object rotating around the sun, discovered at the first of november 1977 by C. Kowal, with an estimated diametre of 500 km.
Chromosphere
One of the layers in the atmosphere of the sun of other stars, lying ontop of the photosphere.
Cluster
A group of physiologicaly the same stars. A cluster or swarm of galaxies means such a group of extragalactic systems, containing 100-10000 galaxies, for instance the Comacluster and the Virgocluster. A group of clusters form a supercluster.
Coma
The thin gascloud which is located around the core of a comet.
Comacluster
A very large spacious group of extragalactic galaxies in the sign of the zodiac Hoofdhaar van Bernice.
Comet
See : solarsystem
Compton-effect
The difusion of x-rays to free electrons, during which these are submitted to a revulsion and take over part of te impulse and energy of the radiation.
Conjunction
Scematic representation of both conjunctions of Mercury, the (upper)conjunction of Mars and the (lower)conjunction of the Moon.
Corona
A vast, thin and hot gasshell around certain types of stars, among which the sun. The suns corona can be seen as a garland of rays during a total solar eclipse.
Cosmic radiation
Radiation that penetrates the atmosphere of the earth as primary radiation, where it reacts with the atmosphere and forms secundary radiation.
Cosmos
An acronym for 'the universe'
Cosmology
The study of everthing there is to know about the universe
Crab nebula
Luminescent nebula in the sign of the zodiac Bull, made up from remnants of a supernova, that, according to chinese history, take place in the year 1054. These remnants have been identified as comming from a supernova
Cygnides
Swarm of meteorites with radiant in the sign of the zodiac Swan (Cygnus).
Cygnus A
The first dotshaped radiosource discovered(1 946), located in the sign of the zodiac Swan.