📚 The Earth in Space: Day, Night, Seasons and Eclipses | 地球在太空：昼夜、季节与日食月食
This Cambridge Stage 8 revision note explains how the Earth and Moon move in space, why we get day and night, why seasons change, and how eclipses happen. Use the paired English-Chinese notes to check your understanding and prepare for topic tests.
本篇 Cambridge Stage 8 复习笔记讲解地球和月球在太空中的运动，解释昼夜交替、季节变化以及日食和月食的成因。请对照中英文笔记检查理解，为主题测验做好准备。
1. Earth’s Rotation and Day/Night | 地球自转与昼夜
Earth spins around an imaginary line called its axis. One full spin takes about 24 hours, which we call one day. The side of Earth facing the Sun has daylight, while the opposite side is in darkness.
地球绕着一根假想的轴旋转，称为地轴。完整自转一圈约需 24 小时，也就是一天。地球朝向太阳的一面是白昼，背向太阳的一面是黑夜。
This rotation gives the Sun its apparent movement across the sky from east to west during the day. At any moment, half of Earth is lit by the Sun and half is in shadow.
这种自转使太阳看起来每天从东向西穿过天空。在任一时刻，地球有一半被太阳照亮，另一半处于阴影中。
2. Earth’s Orbit and the Year | 地球公转与一年
Earth also travels around the Sun in a nearly circular path called an orbit. One complete orbit takes about 365.25 days, so we call this one year. The extra 0.25 day is why we add a leap year every four years.
地球还沿着接近圆形的轨道绕太阳运行，这称为公转。完成一圈公转约需 365.25 天，也就是一年。多出的 0.25 天就是每四年增加一个闰年的原因。
Earth orbits the Sun in the same direction as it rotates on its axis: counterclockwise when viewed from above the North Pole. The orbit is slightly elliptical, but it is close to a circle for most calculations at Stage 8.
地球绕太阳公转的方向与自转方向相同：从北极上方看为逆时针。公转轨道略呈椭圆形，但在 Stage 8 的大多数计算中可视为接近圆形。
3. The Tilted Axis and Seasons | 地轴倾斜与季节
Earth’s axis is tilted at about 23.5° from the vertical. As Earth orbits the Sun, this tilt makes one hemisphere lean towards the Sun for part of the year and away from the Sun for another part. This tilt causes the seasons, not the changing distance from the Sun.
地轴与竖直方向约成 23.5° 的倾角。地球绕太阳公转时，这种倾斜使一个半球在一年的部分时间倾向太阳，另一部分时间远离太阳。正是地轴倾斜造成季节变化，而不是距离太阳的远近变化。
When the Northern Hemisphere leans towards the Sun, it receives more concentrated sunlight and longer daylight hours, so it experiences summer. At the same time, the Southern Hemisphere leans away, receiving less concentrated sunlight and shorter daylight hours, so it experiences winter.
当北半球倾向太阳时，它获得更集中的阳光和更长的白昼时间，因此经历夏季。与此同时，南半球远离太阳，获得较不集中的阳光和较短的白昼时间，因此经历冬季。
4. Solstices and Equinoxes | 夏冬至与春/秋分
In June, the Northern Hemisphere leans most towards the Sun, producing the summer solstice and the longest day of the year. In December, it leans most away, producing the winter solstice and the shortest day of the year.
六月，北半球最倾向太阳，出现夏至和一年中最长的白昼。十二月，北半球最远离太阳，出现冬至和一年中最短的白昼。
Equinoxes occur in March and September, when neither hemisphere is tilted towards the Sun. At these times, day and night are roughly equal all over the world.
春分和秋分出现在三月和九月，此时两个半球都不向太阳倾斜。在这两个时刻，全球各地的昼夜大致等长。
5. The Moon’s Orbit and Phases | 月球轨道与月相
The Moon orbits Earth about once every 27.3 days. It does not make its own light; we see the Moon because it reflects sunlight. The changing shape we see, from new moon to full moon and back, is called the lunar phases.
月球约每 27.3 天绕地球一圈。月球本身不发光，我们能看到它是因为它反射太阳光。我们从新月到满月再回到新月看到的形状变化，称为月相。
During a new moon, the Moon is between the Sun and Earth, so its lit side faces away from us. During a full moon, Earth is between the Sun and Moon, so the full lit side faces us. Half-moon phases occur when the Moon is at right angles to the Sun-Earth line.
新月时，月球位于太阳和地球之间，因此它被照亮的一面背对我们。满月时，地球位于太阳和月球之间，因此完整被照亮的一面朝向地球。半月相出现在月球与日地连线成直角时。
6. Solar and Lunar Eclipses | 日食与月食
A solar eclipse occurs when the Moon passes exactly between the Sun and Earth, casting a shadow on Earth. People inside the darkest part of the shadow, the umbra, see a total solar eclipse. People in the lighter outer shadow, the penumbra, see a partial solar eclipse.
当月球正好经过太阳和地球之间并在地球上投下阴影时，发生日食。位于阴影最暗部分（本影）的人会看到日全食；位于较亮的外阴影（半影）中的人会看到日偏食。
A lunar eclipse occurs when Earth passes between the Sun and Moon, so Earth’s shadow falls on the Moon. Lunar eclipses can be total or partial, and they are visible from anywhere on Earth where the Moon is above the horizon at that time.
当地球位于太阳和月球之间、地球的影子落在月球上时，发生月食。月食可以是全食或偏食，并且在当时月球位于地平线上的任何地方都能看到。
7. Why Eclipses Are Not Monthly | 为什么不是每月都有日食或月食
The Moon’s orbit around Earth is tilted about 5° relative to Earth’s orbit around the Sun. Therefore the Moon usually passes above or below the Sun-Earth line. Eclipses only happen when the Sun, Earth and Moon are almost perfectly aligned.
月球绕地球的轨道相对地球绕太阳的轨道约倾斜 5°。因此，月球通常会经过日地连线的上方或下方。只有当太阳、地球和月球几乎完全对齐时，才会发生日食或月食。
This is why we do not get a solar eclipse at every new moon or a lunar eclipse at every full moon. The alignment needed for an eclipse is much more precise than the ordinary new moon or full moon alignment.
这就是为什么不是每个新月都会发生日食，也不是每个满月都会发生月食。日食或月食所需的对齐比普通新月或满月的对齐要精确得多。
8. The Moon and Tides | 月球与潮汐
The Moon’s gravity pulls on Earth’s oceans, causing bulges of water. These bulges produce high tides on the side of Earth facing the Moon and on the opposite side, with low tides between them. The Sun also affects tides, but its tidal effect is weaker than the Moon’s because it is much farther away.
月球的引力吸引地球上的海洋，形成水的隆起。这些隆起使正对月球的一侧和背对月球的一侧出现高潮，中间区域出现低潮。太阳也影响潮汐，但由于它距离地球远得多，其潮汐作用比月球弱。
Spring tides occur when the Sun, Earth and Moon are aligned, so the Sun and Moon pull together and produce higher high tides and lower low tides. Neap tides occur when the Sun and Moon are at right angles, producing smaller differences between high and low tide.
当太阳、地球和月球对齐时，会发生大潮，太阳和月球的引力共同作用，产生更高的高潮和更低的低潮。当太阳和月球成直角时，会发生小潮，高潮和低潮之间的差异较小。
9. Key Data Check | 关键数据检查
Use this table to review the numerical facts that often appear in Stage 8 questions. Compare the English and Chinese terms carefully.
用下表复习 Stage 8 题目中经常出现的数字事实，并仔细对照中英文术语。
| Quantity 量 | Value 数值 |
|---|---|
| Earth rotation period 地球自转周期 | about 24 hours 约 24 小时 |
| Earth orbital period 地球公转周期 | about 365.25 days 约 365.25 天 |
| Axial tilt 地轴倾角 | about 23.5° 约 23.5° |
| Moon orbital period 月球公转周期 | about 27.3 days 约 27.3 天 |
| Moon orbit tilt 月球轨道倾角 | about 5° 约 5° |
10. Common Misconceptions | 常见误区
Misconception 1: Seasons are caused by Earth moving closer to or farther from the Sun. The correct explanation is that seasons are caused by Earth’s tilted axis and the angle of sunlight.
误区一：季节变化是由地球靠近或远离太阳引起的。正确解释是：季节变化由地轴倾斜和阳光照射角度引起。
Misconception 2: The Moon produces its own light. The correct explanation is that the Moon only reflects light from the Sun.
误区二：月球自己会发光。正确解释是：月球只反射来自太阳的光。
Misconception 3: A solar eclipse happens at every new moon. The correct explanation is that a solar eclipse only happens when the Moon’s tilted orbit brings it exactly in line with the Sun and Earth.
误区三：每个新月都会发生日食。正确解释是：只有当月球倾斜的轨道使它恰好与太阳和地球对齐时，才会发生日食。
11. Exam-Style Quick Questions | 考试风格快速题
1. Explain why a solar eclipse does not occur at every new moon.
1. 解释为什么不是每个新月都会发生日食。
2. Describe the difference between a solar eclipse and a lunar eclipse.
2. 描述日食和月食的区别。
3. State one piece of evidence that the Moon reflects light rather than producing its own light.
3. 说出一个证据，说明月球是反射光而不是自己发光。
4. Explain why the Northern Hemisphere has winter in December even though Earth is slightly closer to the Sun in January.
4. 解释为什么北半球在十二月是冬季，尽管地球在一月还略靠近太阳。
12. Summary | 总结
Earth’s rotation gives day and night, while its tilted axis and yearly orbit give the seasons. The Moon’s orbit explains lunar phases, eclipses, and the main pattern of ocean tides. Understanding these linked motions helps you answer Stage 8 Earth and space questions with confidence.
地球自转产生昼夜，地轴倾斜和年度公转产生季节。月球轨道解释了月相、日食月食和海洋潮汐的主要规律。理解这些相互联系的运动，能帮助你自信地回答 Stage 8 地球与太空相关题目。
Published by TutorHao | Cambridge Lower Secondary Science Stage 8 Revision Series | aleveler.com
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