Solar Facts 2
AUGUST 26th 2006 Press Release The International Astronomical Union [ IAU ] members at the 2006 General Assembly agreed that a "planet" is defined as a celestial body that
(A) Is in orbit around the Sun
(B) Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape
(C) Has cleared the neighbourhood around its orbit.
This means that the Solar System consists of eight 'planets' Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called 'dwarf planets' was also decided. It was agreed that 'planets' and 'dwarf planets' are two distinct classes of objects. The first members of the 'dwarf planet' category are Ceres, Pluto and 2003 UB313 (temporary name). More "dwarf planets" are expected to be announced by the IAU in the coming months and years. Currently a dozen candidate 'dwarf planets' are listed on IAU's 'dwarf planet' watch list, which keeps changing as new objects are found and the physics of the existing candidates becomes better known. The "dwarf planet" Pluto is recognised as an important proto-type of a new class of trans-Neptunian objects. The IAU will set up a process to name these objects.
SEPT 14th 2006 Press Release The International Astronomical Union announces the names (136199) Eris for the dwarf planet provisionally named 2003 UB 313 and Dysnomia for its moon. The dwarf planet formerly known as 2003 UB 313 received the official designation (136199) Eris, or Eris in short, from the International Astronomical Union on 13 September 2006. The name was accepted almost unanimously by the Working Group for Planetary System Nomenclature (WGPSN) and the Committee for Small Body Nomenclature (CSBN). Eris is the second dwarf planet in a sub category of objects of which Pluto is the prototype. The name Eris was proposed by the discovery team. (136199) Eris was discovered 5 January 2005, from data obtained on 21 October 2003 by M. E. Brown, C. A. Trujillo, and D. Rabinowitz at the Palomar Observatory. Eris is a Greek goddess of discord and strife. She stirs up jealousy and envy to cause fighting and anger among men. At the wedding of Peleus and Thetis, the parents of the Greek hero Achilles, all the gods with the exception of Eris were invited, and, enraged at her exclusion, she spitefully caused a quarrel among the goddesses that led to the Trojan War.
So to recap we have 1 star which is the Sun and is at the centre of our Solar System with the 8 planets and all the other bodies in orbit around the Sun as in the diagram above, all held in their orbits by the Suns gravity. Our Sun is just like all the other stars you see in the night sky, some are smaller and some larger, our star being classed as medium in size. When you look at figures of distances and size of our Solar System many people find it difficult to relate to these figures, but if you think of our Solar System set in the Universe it is very tiny, if you could reduce the Universe to say the size of a soccer or football pitch our Solar System would fit twice inside the size of an average garden pea.
Our planets are split into 2 groups, the four inner Planets known as The Rockies and the four Outer Planets known as the Gas Giants, this relates to the makeup of these planets. As you can see in the diagram above the inner planets are closer together compared to the outer planets, but when you think at the moment our technology is barely getting man on our Moon let alone thinking of reaching near or far planets, there will have to be a much improved source of power for the spacecraft than is known at this time.
How big is our Solar system, well the size was always based very roughly around Pluto’s orbit of the Sun which is an ellipse shape rather than a round orbit, but now if dwarf planets are included the size must relate to the orbit of Eris which is approximately 9.15 billion miles from the Sun so double that would be 18.30 billion miles across it’s orbit which should be the outer reaches of our Solar System, when you look at 18.30 billion miles it does not look much but to relate to distances our planet Earth is just 93 million miles from the Sun and if we were in a jet travelling at 600 mph it would take 17 years to reach the Sun and we are talking in just millions rather than billions. From all the sites and publishing’s we visited we could not find an exact size anywhere but logically it must finish around or about the last planet or in this case the last dwarf planet.
Other bodies included in our Solar System is the Asteroid belt orbiting between Mars and Jupiter which has numerous irregular shaped objects ranging in size from the dwarf planet Ceres down to bits of dust, it is also known as the Main Belt but this may change to be the Kuiper Belt which is now well within our Solar System with the introduction of Ceres.
The Kuiper Belt which is a huge ring of debris orbiting outside of Neptune’s orbit, the debris is similar to the Asteroid belt orbiting between Mars and Jupiter but is mainly composed of ice. Some other larger named objects in the belt such as Orcus, Varuna and Quaoar may be classified as dwarf planets in the future. There are estimated to be over 100,000 objects with a diameter larger than 30 miles to be in the belt.
With all the billions upon billions of stars in the Universe it is not unreasonable to think there must be other solar systems similar to ours which may support some sort of life form, but for many years to come they will have to contact or visit us, lets just wait and see.
Mercury is the closest planet to the Sun and is the second smallest in our solar system it has no known moons or satellites. Originally it had two names by the Greeks they were Apollo for the morning and Hermes for the evening although they realised it was the same planet. Being the closest planet to the Sun the temperatures can soar up to 465c in the day but drop as low as -180c at night. The terrain is similar to the moon with dusty hills and hundreds of craters caused by colliding meteors and other objects, the atmosphere is made up with mainly Helium and Sodium both at about 42% with 15% Oxygen and 1% others. Recently scientists believe there is a slight magnetic field at about 1% of Earths. Mercury has an eccentric orbit though not as much as Pluto but does mean its distance from the Sun varies greatly from 46,000,000 to 70,000,000 km usually most fact sheets show an average distance for these two planets. Any spacecraft approaching Mercury from Earth will have problems from the Suns gravitational pull, however there is a planned mission in 2013 by Japan and the European Space Agency which is named Bepi Columbo and this will take approx 6 years as it will be passing the Moon and Venus before making several approaches to Mercury before entering an orbit, two probes will be used on this mission, one to map the planet and one to study its magnetosphere. The mission is named after Giuseppe Bepi Colombo, the scientist who first discovered the nature of the spin orbit resonance of Mercury. The mean surface temperature of Mercury is 442k but it varies from 199k to 700k due to the absence of an atmosphere, although the surface can reach high temperatures reports state that ice exists on the floors of deep craters as the temperatures are a lot lower, some of the water is thought to be sourced from the impact of comets.
Sodium and potassium were discovered in the atmosphere during the 1980s, and are believed to result primarily from the vaporization of surface rock struck by micrometeorite impacts. Due to the ability of these materials to diffuse sunlight Earth-based observers can readily detect their composition in the atmosphere. Studies indicate that, at times, sodium emissions are localized at points that correspond to the planets magnetic dipoles.
Venus is known to astronomers as Earths sister planet as they were formed about the same time and from the same nebula, but it is not similar in many other ways and would be impossible to live on with an atmosphere of 96% carbon dioxide, 3% nitrogen and small amounts of others including water vapour, hydrogen chloride, helium and argon plus a few others but all these only add up to 1%. Although Venus is further away from the Sun than Mercury it is hotter, this is because of a runaway greenhouse effect caused by the already stated carbon dioxide atmosphere and temperatures can rise to a blistering 480c. Venus also has a very dense cloud cover which until recent years made it difficult to gather information of the planet, recent missions by NASA and Russia has vastly improved the information now available. Venus is the brightest natural object in the night sky apart from the Moon, it reaches its maximum brightness just before sunrise or just after sunset, it is often referred to as The Morning Star or The Evening Star. It also has the densest atmosphere of all the terrestrial planets, the atmospheric pressure at the planets surface is 90 times that of the Earth. Some reports state that at one time there were large amounts of water on this planet but have now boiled away. Venus is not known to have any moons or satellites. The minimum distance of Earth from Venus is 40 million km.About 80% of the surface on Venus is smooth volcanic plains the remainder is taken up by two highland continents, in the northern hemisphere is Ishtar Terra and is about the size of Australia, the other is Aphrodite Terra just south of the equator and is about the size of South America.
Venus actually rotates from east to west, as opposed to west to east which is the common rotating direction of most other planets in our Solar System except Uranus. The orbit of Venus is very slow, taking 225 days for one rotation of the Sun. The diameter of Venus is almost identical to that of Earth. Scientists believe that Venus has a dense iron core and internal structure similar to Earth.
Venus has a long history, it was known to the Babylonians and the Hebrews. It was also important to the Maya civilisation they named it Noh Ek, the Great Star, and Xux Ek the Wasp Star. The Maasai people named it Kileken. Venus was also important to many Australian Aboriginal cultures.
Our wonderful home planet and the only habitable planet known to man, most reports state that our planets surface is covered by between two thirds and three quarters with water. On its yearly orbit of the Sun our home planet travels up to 67,000 miles per hour only slowing slightly as its orbit takes it slightly further away from the Moon. It was not until during the 16th century that it was discovered that Earth was another planet. Our atmosphere consists of 77% nitrogen, 21% oxygen with small amounts of water, argon and carbon dioxide making the other 2%. Research now shows that 900 million years ago we had 481 days in our year but they were only 18 hours long. Earths crust is made of nearly 30 separate plates, the major eight being the South American plate, North American plate, Pacific plate, Nazca plate, Antarctic plate, Eurasian plate, African plate and Indian-Australian plate. Earth is the first planet from the Sun to have a Moon, although nearly everyone names it The Moon it was named Luna by the Romans and Selena and Artemis by the ancient Greeks. Comet bombardments during the early history of our planet played a role in the formation of the oceans. Later, asteroid impacts caused significant changes to the surface environment. Long term periodic changes in the orbit of the planet are believed to have caused the ice ages that have covered significant portions of the surface of the Earth in glacial sheets.Earth is a terrestrial planet which means it is rocky rather than a Gas Giant, it is the largest of the terrestrial planets in terms of size and mass. Earth has 6.74 billion inhabitants as of November 2008 and is expected to reach 7 billion by 2013, and 9.2 billion in 2050. It is estimated that only 8% of Earths surface is suitable for human habitation. 30% of the Earths total land is grass covered, from the ordinary fields to the Great Plains.
The Earths atmosphere has no definite boundary, it slowly becomes thinner and fades into outer space. Three quarters of the atmospheres mass is contained within the first 11 km of the planets surface. This lowest layer is called the troposphere. Above the troposphere the atmosphere is divided into three being the stratosphere, mesosphere and the thermosphere. 100 km above the Earths surface is the Karman Line which is the working definition for the boundary between atmosphere and space.
Mars is often referred to as the Red planet purely because of its colour in the night sky, it may be seen by the human eye without binoculars or telescope. It has snow and ice at both its north and south poles with an average temperature of between -55c and -65c but also reaches -130c but during summer on the day side it can reach 27c. Mars has one of the most interesting terrains of all the planets in the Solar System with a mountain three times higher than Mt Everest it reaches 78,000 feet and is named Olympus Mons , it also has a system of canyons over 4,000 km long and up to 7 km deep and is named Valles Marineris, Hellas Planitia is a crater measuring 2,000 km wide and 6 km deep. Mars also has the largest dust storms in the Solar System. These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase the global temperature. The atmosphere on Mars is made up of 95% carbon dioxide just under 3% nitrogen and traces of oxygen, water and neon. Mars is known to have two moons, Phobos with a 22 km diameter and Deimos with a 12 km diameter. There have been dozens of spacecraft missions to Mars sent by NASA, Europe, Russia and Japan but only approx one third of these have been successful, they all usually have technical problems or suffer a loss of communication.
The mighty Jupiter is the first of the gas giants and after the Sun is the largest object in our Solar System, it is large enough to fit the mass of the other seven planets inside its self twice. Some reports state that Jupiter has four large moons while others refer to them as satellites the large moons are named Europa, Io, Ganymede and Callisto these were discovered by Galileo in 1610 there are also 36 smaller bodies which most term as satellites but most of them do not have any names and very little is known about them. The gas planets have no solid surface and the outer gas just gets denser and is 90% hydrogen and 10% helium with traces of methane, water, ammonia and rock. This composition is very similar to the composition of the Solar Nebula which formed the whole of the Solar System. Jupiters rings are smaller than Saturns and are not visible from Earth, they are said to be formed from small grains of rock. Jupiters best known feature is a huge red spot named The Great Red Spot which is a raging storm the size of Earth and was first discovered by Galileo approx 400 years ago, it is suggested in some reports that the storm could be a permanent feature of this planet.
Uranus is tipped on its side and the poles face rhe Sun, which is believed to have happened by colliding with another celestial body thousands of years ago, it also spins from east to west the opposite way to Earth. Uranus was named after the ancient Greek God of the Heavens and was discovered by William Herschel in1781, its rings were not discovered until 1977, it has only had one visitor from Earth and that was Voyager 2 in January 1986, during this visit the rings were measured and photographed, also two new rings were found. Again the atmosphere is very similar to Jupiter and Saturn, whilst researching these pages we keep finding some variations on certain facts and the number of moons Uranus has vary between 11 and 27 but most reports name 20 which were all named after characters from Shakespear and Alexander Pope, they are Ariel, Belinda, Bian, Caliban, Cressida, Cordelia, Desdemona, Juliet, Miranda, Oberon, Ophelia, Portia, Prospero, Puck, Rosalind, Setebos, Stephano, Sycorax, Titania and Umbriel.
Neptune is the fourth largest planet in our solar system and is eighth from the Sun and because of the new changes it is now the farthest planet from the Sun.This planet has the strongest winds of all the planets and large storms of vortices, the winds can reach 2,000 km ph. Neptune was first observed by John Gottfried Galle in 1846 but he first thought it to be another star. It has several large spots the largest being nearly the size of Earth and is named The Great Dark Spot, it seems there was not much imagination used with this name. Neptune has a very complex ring system with five named rings and two unnamed, one ring named "Adams" also has 3 named arcs.The widest ring being just 4,000 km. Neptunes colour is caused by huge clouds of blue methane gas, it is the only gas giant that has high clouds casting shadows on the opaque cloud deck below, its atmosphere is much more dynamic than that of Uranus, both planets are made of the same gases and ices, although Neptune and Uranus are not strictly gas giants similar to Jupiter and Saturn, but are more like ice giants. It also has thirteen known moons but only eight of them have yet been named, the largest is Triton the other seven are Naiad, Thalassa, Despina, Galatea, Larissa, Proteus and Nereid. 
Pluto is definitely not a gas giant or a giant of any kind and has now been re-classified as a Dwarf Planet and is in fact smaller than several moons including our Moon, many people have been trying to accomplish this for several years. Only discovered in 1930 by Clyde W Tombaugh there is still much to be researched about this planet, it has not yet been visited by any spacecraft, but a mission was launched in January this year [2006] by Nasa and the craft is named New Horizon and will reach Pluto in 2015. The composition is also not known but some reports suggest it to be 70% rock and 30% water and ice. It has been confirmed that Plutos poles are on its orbital plane similar to Uranus. It also has 3 satellites but only one has yet been named and it is Charon. Although the above press releases give the basic information there is still much to be sorted in the coming months. Appeals have already been submitted by various groups to have it re-instated.
Officially named 136199 ERIS it is the largest of the 3 new dwarf planets also known as scattered disks and is orbiting the Sun beyond the Kuiper belt which is where it is thought to have originated from and is currently approx 14.5 billion km from Earth, it could be years until clear photographs are available, it is approx 2397 km in diameter. Eris was first discovered in 2005 from images taken in 2003. It takes Eris 556.7 years to complete one orbit of the Sun. In mythology, Eris caused a quarrel among goddesses that sparked the Trojan War. In real life, Eris also caused strife, forcing scientists to produce a strict definition of the term planet - and that also eventually led to Pluto losing the status it had held since its discovery in 1930. Eris was originally not named but given the number 2003 UB313 but had a codename by its discoverer Michael Brown which was "XENA". It also has its own satellite named Dysnomia. Opposite is an image provided by NASA for public use.
Now officially named 1 CERES was first discovered in 1801 by Giuseppe Piazzi and is orbiting in the asteroid belt which is orbiting between Mars which is the last of the Rockies and Jupiter which is the first of the Gas Giants, and has an orbit time of 4.6 Earth years, it has a diameter of 950km. Observations coupled with computer models suggest the presence of a rocky core overlain with an icy mantle. This mantle of thickness from 120 to 60 km could contain 200 million cubic kilometres of water, which is more than the amount of fresh water on the Earth. Opposite is a UV image taken by the Hubble Space Telescope in 1995, it also observed a large spot which is believed to be a crater formed by another asteroid crashing into Ceres. NASA's launch of "Dawn Mission" is expected to reach Ceres in 2014 giving us new information.