IGCSE Edexcel Science: Earth and Space Revision Guide | IGCSE Edexcel 科学：地球与太空 考点精讲

📚 IGCSE Edexcel Science: Earth and Space Revision Guide | IGCSE Edexcel 科学：地球与太空 考点精讲

Welcome to your comprehensive revision guide for the Earth and Space topic in IGCSE Edexcel Science. This guide covers everything from our solar system to the expanding universe, with clear explanations of key concepts and exam tips.

欢迎阅读 IGCSE Edexcel 科学中地球与太空主题的全面复习指南。本指南涵盖从太阳系到膨胀宇宙的所有内容，清晰解释关键概念并提供考试技巧。

1. The Solar System | 太阳系

Our Solar System is located in the Milky Way galaxy, one of billions of galaxies in the Universe. The Solar System formed about 4.6 billion years ago from a cloud of gas and dust.

我们的太阳系位于银河系中，银河系是宇宙中数十亿个星系之一。太阳系大约在46亿年前由气体和尘埃云形成。

The Sun is at the centre, containing over 99% of the Solar System’s mass. It is a medium-sized star that produces energy through nuclear fusion of hydrogen into helium in its core.

太阳位于中心，包含了太阳系超过99%的质量。它是一颗中等大小的恒星，通过核心中氢聚变成氦的核聚变产生能量。

The eight planets in order from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The first four are rocky inner planets; the outer four are gas giants (Jupiter and Saturn) and ice giants (Uranus and Neptune).

八大行星按距太阳由近到远依次为：水星、金星、地球、火星、木星、土星、天王星、海王星。前四颗是岩质内行星；外四颗是气态巨行星（木星和土星）和冰巨行星（天王星和海王星）。

Between Mars and Jupiter lies the asteroid belt, containing many rocky bodies. Comets orbit the Sun in highly elliptical paths, developing tails of gas and dust when near the Sun.

火星和木星之间是小行星带，包含许多岩石天体。彗星以高度椭圆的轨道绕太阳运行，当靠近太阳时会形成气体和尘埃尾。

2. Earth’s Rotation and Day/Night | 地球自转与昼夜交替

The Earth rotates on its axis once every 24 hours (23 hours 56 minutes relative to stars). This rotation causes the cycle of day and night as different parts of the Earth face the Sun.

地球每24小时绕其轴自转一圈（相对于恒星为23小时56分钟）。这种自转导致昼夜交替，因为地球的不同部分面向太阳。

The axis of rotation is tilted at about 23.5° relative to the plane of its orbit. The side facing the Sun experiences daylight, while the opposite side experiences night.

自转轴相对于轨道平面倾斜约23.5°。面向太阳的一面经历白天，而背向太阳的一面则为黑夜。

The apparent movement of the Sun across the sky (east to west) is due to Earth’s rotation from west to east.

太阳在天空中明显的东升西落运动是由于地球自西向东自转造成的。

3. Earth’s Revolution and Seasons | 地球公转与四季

The Earth revolves around the Sun in an elliptical orbit, taking approximately 365.25 days to complete one orbit. This defines a year.

地球以椭圆轨道绕太阳公转，完成一周大约需要365.25天，这定义了一年。

Seasons are caused by the tilt of Earth’s axis, not by changes in distance from the Sun. When the Northern Hemisphere tilts towards the Sun, it receives more direct sunlight and experiences summer; meanwhile, the Southern Hemisphere tilts away and has

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