太阳系火星、水星、地球、太阳、金星各自的英文简介.

火星Mars
Mars is the fourth planet from the sun and often referred to as the red planet. It is often used as an alien planet in science fiction, for example, H G Wells' The War of the Worlds. The reddish colour is due to iron (III) oxide in the surface minerals.
Mars started out as a Roman god of agriculture, but became the god of war, because of affiliation with the Greek Ares.
Mars' orbit is slightly elliptical, not so strongly as Mercury or Pluto, but enough to make large temperature variations, between 140K and 220K (average 218K).
Mars has two moons, Phobos and Deimos, both discovered by Asaph Hall in 1877.
Mars has been visited on several occasions, first by Mariner 4 in 1965. Then by the USSR's Mars 2 lander in 1971 and the Viking landers in 1976. More recently, in 1997, Mars Pathfinder landed and the Expedition Rovers in 2004. The rovers, Spirit and Opportunity, have far outlasted expectations and are still running as of 2006. In addition, Mars Global Surveyer, Mars Odyssey and ESA's Mars Express are still in orbit. Also, Mars Reconnaissence Orbiter arrived in March 2006. Another lander, Phoenix, is planned to launch in 2007 to descend to Mars in May 2008.
The Martian atmosphere is thin and consists mostly of carbon dioxide. By composition, it is; carbon dioxide 95.3%, nitrogen 2.7%, argon 1.6%, oxygen 0.15% and water 0.03%. There are sometimes dust storms that can last for several months. The atmospheric pressure at the surface is only 1% of that on Earth.
Mars has some incredible surface features, such as Olympus Mons; a mountain over 24km higher than its surroundings and with a 250km radius (slightly under the distance between Paris and Brussels). Also, the Valles Marineris; a vast set of canyons 7km deep at its maximum, spreading 4000km. Recent expeditions sent back images and data suggest that Mars had large amounts of liquid on its surface at some point in its past. The poles of Mars are capped with water ice and frozen carbon dioxide.
水星Mercury
Mercury is the nearest planet to the sun. It has the most extreme contrast in temperature between day (430°C) and night (-180°C) in the solar system. Daytime temperatures are high enough to melt zinc and tin. Mercury has virtually no atmosphere, meaning life as we know it is impossible.
Mercury was the Roman god of trade and commerce, in the same vein as Hermes of the Greeks, the messenger.
Mercury's orbit is highly eccentric, meaning it's path is elliptical. Also, mercury rotates three times for every two orbits of the sun. Mercury has no satellites.
Only one spacecraft has been to mercury, Mariner 10, passing three times in 1974-75. However NASA's Messenger is on the way, launched in August 2004, and will fly by three times and then enter mercury orbit in March 2011. Then in 2012, ESA/ISAS's BepiColombo will be launched, also into mercurian orbit. Because of mercury's proximity to the sun, it cannot safely be photographed by the Hubble Space Telescope.
Mercurian atmosphere is thin enough to be described as an exosphere, meaning the constituent atoms never collide. The identified elements in the exosphere are sodium, potassium, hydrogen, oxygen and neon. Ions and high frequency electromagnetic radiation from the sun are responsible for dislodging the atoms in the exosphere.
The surface of mercury is splattered with craters, the majority being formed in the early days of the solar system when rocky bodies moving at high speeds around the sun collided with the planet. The nonexistence of atmosphere meant that there was nothing to cushion the incoming bodies. Flat plains suggest possible volcanic activity. Earth based radar observations hint at possible water ice in the pole craters, possible only because of permanent shadow. The Caloris Basin is a notable landmark, a giant crater having a 650 km radius and is similar to the lunar basins.
Mercury is the second most dense planet after earth. The earth has more mass and so part of this density is attributable to gravitational compression. We can only speculate at the core composition of mercury, but it has a very high density for its radius so it is likely to have a large metallic core accounting for most of its mass. In this, mercury differs from the other terrestrial planets. Possible explanations are that mercury formed in an iron rich part of the early solar system, the sun's rays have reduced the metal oxides to solid metals which are denser, collisions or energy from the sun may have removed part of a less dense crust.
Mercury's point of perihelion was noticed to rotate the sun faster than predicted by Newton's laws of gravitation and proved to be strong evidence for Einstein's gravitational model; general relativity.
地球Earth
Earth is the third planet from the sun and funnily enough, the one we know the most about.
The Earth's atmosphere is composed of; nitrogen 78%, oxygen 21%, argon 1% and traces of carbon dioxide, neon and helium. Water vapour concentrations are always variable, but are roughly 1%.
Earth has one natural satellite, the Moon, which orbits at 384,000km and is responsible for the tides.
From the surface, the atmosphere is labelled the troposphere for the first 14km up, then the tropopause (4km height), then the stratosphere (about 32km height), then the mesosphere (40km), then the ionosphere (over 600km in height) and finally the exosphere (another 200km), which is the boundary of space. The pressure at the top of the troposphere is only 10% of that at sea level and above this layer the pressure continues to drop. Weather as we know it also takes place in the troposphere, with the rising and falling of air through convection. The ozone layer is a thin region of the upper stratosphere which protects us from ultraviolet radiation. The ionosphere gets its name because it's teeming with ions and though it's very thin, it reflects radio waves, which is how radio communication works. It is also the region where the aurora take place.
The Earth's crust varies in thickness from 5-10km under the oceans and 20-70km on the continents and is mostly silicon dioxide (quartz). It is broken into several large pieces called plates, which effectively float on the liquid mantle. Where these plates are coming together, mountain ranges are formed, such as the Andes in South America. The mantle is roughly 2,900km thick, makes up 84% by volume and is solid/plastic. By composition, the outer mantle (350km thick) is mostly iron and magnesium silicates while the inner mantle is mostly magnesium, silicon, oxygen and iron. The mantle also contains some calcium and magnesium. The liquid outer core extends in radius from about 1220km to 3500km and is made of iron and nickel, whilst the solid inner core is volume contained by it and is almost entirely iron. It is thought the inner core may rotate slightly faster (0.5 degrees per year) than the the surface.
By mass, the Earth's composition is; iron 35.1%, oxygen 28.2%, silicon 17.2%, magnesium 15.9% and 1.5% of nickel, calcium and magnesium each.
The Earth's maximum recorded temperature is 57.8 degrees on 13/09/1922 at El Azizia, Libya. The Earth's minimum recorded temperature is -89.4 degrees on 21/07/1983 at Vostok, Antarctica.