太阳系Solar System
一、太阳系的组成The composition of the solar system
太阳系由太阳、行星和其他物质组成。
The solar system is made up of the sun, the planets, and other objects.
四个较小的内行星，水星，金星，地球和火星，是陆地行星，主要由岩石和金属组成。
The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal.
四个外行星都是巨大的行星，木星和土星是两个最大的气态巨星，主要由氢和氦组成。
两个最外层的行星，天王星和海王星，都是冰巨星。
The four outer planets are giant planets. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants.
二、太阳与行星的尺寸比较Size comparison of the Sun and the planets
太阳直径相当于地球直径的109倍，体积大约是地球的130万倍，其质量大约是地球的330000（33万）倍。
The diameter of the sun is 109 times the diameter of the earth, its volume is about 1 million 300 thousand times that of the earth, its mass is about 330 thousand times that of the earth.
太阳系的八个行星尺寸由大到小是木星、土星、天王星、海王星、地球、金星、
火星和水星。
The eight planets of the Solar System (by decreasing size) are Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars and Mercury。
三、太阳The Sun
1、太阳是太阳系的恒星。
The sun is the star of the solar system.
2、太阳大约是中年，它大约45.7亿岁。
The Sun is roughly middle-aged.It is about 4 billion 570 million years old.
3、日历是以地球绕太阳公转的运动周期为基础而制定的历法。
The solar calendar is a calendar based on the cycle of the earth's revolution around the sun.
四、内行星Inner planets
1、水星是太阳系中最靠近的行星，也是太阳系中最小的行星（地球质量的1/18）。
Mercury is the closest planet to the Sun and the smallest planet in the Solar System (1/18 of the earth's mass).
2、金星质量接近地球。
它是最热的行星，表面温度超过400°C。
Venus is close in size to Earth.
It is the hottest planet, with surface temperatures over 400°C.
3、地球是唯一存在生命的地方。
它的液态水球在陆地行星中是独一无二的。
Earth is the only place where life is known to exist.
Its liquid hydrosphere is unique among the terrestrial planets. 4、火星有一个主要是二氧化碳的大气层。
它的表面上布满了巨大的火山。
Mars has an atmosphere of mostly carbon dioxide.
Its surface, peppered with vast volcanoes.
五、外行星Outer planets
1、木星是地球质量的318倍。
木星有69已知的卫星。
木卫三，太阳系最大的卫星，比水星还大。
Jupiter is 318 times the mass of the earth.
Jupiter has 69 known satellites.
Ganymede, the largest satellite in the Solar System, is larger than Mercury.
2、土星有一个显著的行星环。
土星因其美丽的行星环而被称为太阳系的宝石Saturn has a significant planetary ring
Saturn is known as the gemstone of the solar system because of its beautiful planetary ring.
3、天王星是最轻的外行星，是地球质量的14倍。
Uranus is the lightest of the outer planets. It is 14 times the mass of the earth. 4、海王星比天王星小略小，但比天王星重，因为它有更大密度。
Neptune though slightly smaller than Uranus, is more massive and hence more dense.。