Solar system (solar system) is the star system which we now is at. By the sun, 8 big planets (originally have the nine planets, because pluto is rejected for short planet), 66 satellites (original 67, pluto's satellite is rejected) as well as the innumerable planetoids, the comet and composes. The planet gets up by the sun toward the outside order is: Mercury (mercury), Venus (venus), Earth (earth), Mars (mars), Jupiter (jupiter), Saturn (saturn), Uranus (uranus), Neptune (neptune). To a solar nearer Mercury, Venus, the Earth and Mars are called the kind of place planet (terrestrial planets). The spaceship has all carried on the survey to them, but also once landed on Mars and Venus, has obtained the important achievement. Their common characteristic is the density big (3.0 grams/cubic centimeters), volume small, rotation slow, the satellite are few, internal ingredient mainly for the silicate (silicate), has the solid outer covering. To a solar farther Jupiter, Saturn, Uranus, Neptune are called (jovian planets). They all have the very thick aerosphere, its superficial characteristic is very difficult to understand, the general inference, they all have with the kind of place planet similar solid essence. Has 1 million above between Mars and Jupiter the planetoid (asteroid) (namely irregular small photostar which is composed by rock). Extrapolated they possibly are by the position, or is some which becomes between Mars and Jupiter's some planet disruption has not been able to accumulate into the unification planet the lithical fragment. exists between the planet, the ingredient is lithical or ferroguinous. These planets all take sun as center by elliptical orbit revolution, although extremely approaches except Mercury to the circle. In the planetary orbit more or less (is called ecliptic surface and take the revolution in the identical plane as datum). The ecliptic surface and the solar equator only have 7 inclining. Pluto's track mostly was separated from the ecliptic surface, the gradient has amounted to 17. The above graph specific was higher than the ecliptic surface from to pass the angle of view to demonstrate various tracks relative size and the relations (non- circle phenomenon was obvious). They circle the orbital motion the direction to be consistent (from the solar North Pole looked is counter clockwise), therefore, the scientists remove pluto outside the nine planets. Besides Venus and Uranus rotation direction also so.
    太阳系（solar system）就是我们现在所在的恒星系统。由太阳、8颗大行星（原先有九大行星，因为冥王星被剔除为矮行星）、66颗卫星（原有67颗，冥王星的卫星被剔除）以及无数的小行星、彗星及陨星组成的。行星由太阳起往外的顺序是：水星（mercury）、金星（venus）、地球（earth）、火星（mars）、木星(jupiter）、土星（saturn）、天王星（uranus）、海王星（neptune）。离太阳较近的水星、金星、地球及火星称为类地行星（terrestrial planets）。宇宙飞船对它们都进行了探测，还曾在火星与金星上着陆，获得了重要成果。它们的共同特征是密度大（ 3.0克/立方厘米），体积小，自转慢，卫星少，内部成分主要为硅酸盐（silicate），具有固体外壳。离太阳较远的木星、土星、天王星、海王星称为类木行星（jovian planets）。它们都有很厚的大气圈，其表面特征很难了解，一般推断，它们都具有与类地行星相似的固体内核。在火星与木星之间有1000000个以上的小行星（asteroid）（即由岩石组成的不规则的小星体）。推测它们可能是由位置界于火星与木星之间的某一颗行星碎裂而成的，或者是一些未能聚积成为统一行星的石质碎块。陨星存在于行星之间，成分是石质或者铁质。

    这些行星都以太阳为中心以椭圆轨道公转，虽然除了水星的十分接近于圆。行星轨道中或多或少在同一平面内（称为黄道面并以地球公转轨道面为基准）。黄道面与太阳赤道仅有7度的倾斜。冥王星的轨道大都脱离了黄道面，倾斜度达17度。上面的图表从一个特定的高于黄道面的透视角显示了各轨道的相对大小及关系（非圆的现象显而易见）。它们绕轨道运动的方向一致（从太阳北极上看是逆时针方向）,因此,科学家们把冥王星排除在九大行星之外。除金星和天王星外自转方向也如此。