行星形成之初英文

nihao/By the sun in the solar system by gravitational bound by the celestial bodies formed, to the maximum extent it can be extended to about 1 light-years away. The main members of the solar system: the sun (star), the eight planets (Earth), numerous asteroids, a large number of satellites (including the moon), comets, meteoroid and a large amount of dust material and thin gaseous material. In the solar system, the sun The quality of the solar system accounted for 99.8 percent of the total mass, and other celestial bodies are less than the sum of 0.2 percent of the sun. Sun is the Center for Astrophysics, which controls the gravity of the solar system as a whole, so that other celestial bodies around the sun, the solar system's nine planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) are close to the same plane near Circular orbit, in the same direction around the sun. Distance (AU) radius (Earth) quality (Earth) orbit inclination angle (degrees) orbital eccentricity gradient density (g/cm3) Sun 0 109 332,800 --- --- --- 1.410 Mercury 0.39 0.38 0.05 7 0.2056 0.1 ° 5.43 Venus 0.72 0.95 0.89 3.394 0.0068 177.4 ° 5.25 Earth 1.0 1.00 1.00 0.000 0.0167 23.45 ° 5.52 Mars 1.5 0.53 0.11 1.850 0.0934 25.19 ° 3.95 Jupiter 5.2 11.0 318 1.308 0.0483 3.12 ° 1.33 Saturn 9.5 9.5 95 2.488 0.0560 26.73 ° 0.69 Uranus 19.2 4.0 17 0.774 0.0461 97.86 ° 1.29 Neptune 30.1 3.9 17 1.774 0.0097 29.56 ° 1.64 Eight planets, the general Mercury, Venus, Earth and Mars as the terrestrial planets, their common feature is its stone and iron from the main structure, and quality of the smaller radius, but a higher density. The Jupiter, Saturn, Uranus and Neptune known as the Jovian planets, their common feature is mainly hydrogen, helium, ice, methane, ammonia, etc., stone and iron accounted for only a very small proportion of their quality And are much greater than the radius of the Earth, but the density is lower. Long terms, the distance between planets to the sun (a use that) a = 0.4 +0.3 * 2n-2 (an astronomical unit) n one that is far from near to the first planet-n (see the table) of the Earth, Mars, Jupiter, Saturn , Uranus, Neptune's rotation period to 12 hours a day or so, Mercury, Venus's rotation period is very long, were 58.65 days, 243 days and 6.387 day, most of the planet's rotation and the direction of the revolution in the same direction, but Venus is the opposite. In addition to Mercury and Venus, other planets have Raozhuan satellite, the satellite system poses. In the solar system, has now found more than 1600 comets, most of the comet is in the same direction around the sun, but there are also reverse the revolution. Comet around the Sun in the operation of a strange shape change. In the solar system are a large number of small meteoroids, and some groups of the meteoroid is, the meteor is the product of the collapse of the comet. Large meteoroid landed on the ground to become meteorites. The solar system is an insignificant part of the galaxy, the Milky Way that it is only in the 100,000,000,000 stars in one of its center of the Milky Way from the 1000 second gap of about 8.5, or less than 30,000 light-years. With the sun throughout the solar system rotating around the center of the Milky Way. Can be seen, not in the solar system center of the universe, not in the center of the Milky Way. The sun is 50 million years ago by the collapse of interstellar cloud after a mission Xiaoyun from the collapse of its life span is about 100 million years.

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