Our Solar System

Our Solar System, written by Bruce D. Cooper.

《我们的太阳系》，作者：布鲁斯·D·库珀。

Introduction. Our Solar System is made up of the Sun, eight official planets, several dwarf planets and hundreds of planetary satellites or moons. It also contains comets, asteroids and clouds of gas. The Sun is the center of the Solar System. Everything else in the Solar System goes around or orbits the Sun. Mercury, Venus, Earth and Mars are the inner rocky They are made of hard materials. The outer planets are Jupiter, Saturn, Uranus, and Neptune. They are known as the gas giants and are made mostly of gases. The outer planets are hundreds of times larger than Earth.

前言。 我们的太阳系由太阳、八颗正式行星、若干矮行星，以及数百颗行星卫星（也就是天然卫星）组成。 太阳系里还有彗星、小行星和气云。 太阳是太阳系的中心。 太阳系里所有其他天体都沿轨道围绕太阳运转。 水星、金星、地球和火星是岩质内行星，都由坚硬的物质构成。 外行星分别是木星、土星、天王星和海王星。 它们被称为气态巨行星，主要由气体构成。 这些外行星的体积比地球大数百倍。

To get an idea of the size of things in our solar system, imagine that Earth is a grape. If the Earth were the size of a grape, the Moon would be the size of a green pea. The Sun would be as big as a ball that an adult man could stand in. Jupiter, the largest planet, would be the size of a grapefruit, while Saturn, the second largest planet, would be the size of an orange. Uranus and Neptune would be the size of lemons.

想要感受太阳系天体的大小差距，我们来做个想象：假设地球是一颗葡萄。 如果地球有葡萄那么大，月球就只有青豌豆那么大。 太阳会大到能容下一个成年男子站在里面。 太阳系最大的行星木星会有葡萄柚那么大，第二大的土星则有橙子那么大。 天王星和海王星有柠檬那么大。

The sun. The sun is a huge ball of burning gas that sends energy far out into the solar system. The sun plays a very important part in our daily lives, providing energy that supports all life on earth. The sun causes seasons, climate, ocean currents, air circulation, and weather. Without the sun's energy, plants could not grow and make food. Also, there would be no gas, oil, or coal, which are Earth's fossil fuels. Fossil fuels are formed over millions of years from dead plant and animal life.

太阳。 太阳是一颗巨大的燃烧气体球，它把能量输送到太阳系的各个角落。 太阳在我们的日常生活中至关重要，它为地球上所有生命提供维持生存的能量。 太阳造就了四季、气候、洋流、大气环流和天气。 如果没有太阳的能量，植物就无法生长，也无法制造养分。 也不会有天然气、石油和煤炭这些地球上的化石燃料。 化石燃料是在数百万年里，由死去的动植物慢慢形成的。

The Sun is just one of billions of stars. It has been around for about 4 .6 billion years. It will keep producing energy for another 5 billion years. Before it dies, it will swell up and swallow many of the inner planets. Then it will shrink into a much smaller ball.

太阳不过是数十亿恒星中的一颗。 它已经存在了大约46亿年。 它还能继续产生能量长达50亿年。 在它熄灭之前，会膨胀变大，吞噬掉许多内行星。 之后它会收缩成一颗小很多的星球。

Mercury. Mercury is the closest planet to the Sun. It is the smallest planet in our solar system. It takes only 88 Earth days for Mercury to make a complete orbit around the Sun. For comparison, it takes Earth 365 days, or one year, to orbit the Sun. Like all other planets, Mercury spins like a top as it goes around the Sun. It spins very slowly. Each spin of a planet is a day on that planet. A day on Mercury is 59 times longer than an Earth day. Because Mercury spins or rotates so slowly, it gets very hot during the day and very cold at night.

水星。 水星是距离太阳最近的行星。 它是太阳系里最小的行星。 水星绕太阳公转一周，只需要88个地球日。 对比来看，地球绕太阳公转一周需要365天，也就是一年。 和所有其他行星一样，水星绕太阳运行时，也像陀螺一样自转。 它自转的速度非常慢。 行星自转一周，就是这颗行星上的一天。 水星上的一天比地球上的一天长59倍。 因为水星自转速度非常慢，所以白天极热，夜晚又极冷。