The Solar System and the Universe
FoundationThe sun is the Solar System's only star, pouring out light and heat; planets and the moon shine only by reflecting sunlight, and our galaxy is but one of many in the universe.
- The sun is a star, streaming light and heat energy.
- The moon and planets shine only by reflecting sunlight.
- Eight planets: Mercury to Neptune in order.
文體小知識：說明文帶你遨遊太空。這一篇介紹太陽、八大行星和銀河系，還解答月亮為什麼會發亮的謎題。
§Text Passage
1At night the sky glitters with stars; by day the brightest is surely the sun. The sun is a star — a giant body that shines by itself, giving out its own light and heat. Sitting at the centre of the Solar System, it pours light and heat energy in all directions; the light, warmth and energy for all life on Earth come from the sun.
2What about the moon and the planets? They give off no light of their own. The moon is Earth's satellite and the planets circle the sun; they look bright because, like mirrors, they reflect sunlight into our eyes. So the moon at night is actually lit by the sun, and its reflected light makes it look so bright and clear.
3The Solar System holds eight planets. From nearest to farthest: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The inner four — Mercury, Venus, Earth and Mars — are made mostly of rock; farther out, Jupiter and Saturn are giant gas planets, and Saturn wears beautiful rings; Uranus and Neptune lie far from the sun, cold and dim.
4Among the eight, Earth is the most special: its distance from the sun lets water stay liquid, and its atmosphere supplies oxygen and steadies the temperature. Liquid water, air and a suitable temperature make Earth the only planet known to hold life — a home we must treasure.
5Zoom out further: the sun and its planets dwell inside the Milky Way, a giant galaxy holding hundreds of billions of stars; the hazy band across the night sky is part of it. And the universe holds countless galaxies like ours, so vast the mind can barely picture it.
6The universe amazes and humbles us. Scientists keep exploring with telescopes and spacecraft: lunar rovers land on the moon, probes fly past Saturn's rings, telescopes photograph galaxies billions of light years away. As we admire the cosmos, we should also care for Earth, our precious blue planet in the vastness.
1Summary 重點摘要
The sun is the Solar System's only star, pouring out light and heat; planets and the moon shine only by reflecting sunlight, and our galaxy is but one of many in the universe.
2Vocabulary cards Vocabulary
The system of the sun and the eight planets, moons and more circling it.
A giant body shining with its own light and heat; the sun is our nearest star.
A body circling a star that shines no light of its own, such as Earth.
The Solar System's eight: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Earth's satellite, bright only by reflecting sunlight.
Light bouncing off a surface; the moon shines by reflecting sunlight.
The giant galaxy containing our Solar System, with hundreds of billions of stars.
All galaxies, bodies and space together — boundlessly vast.
The energy carried by light, streamed to us by the sun.
Energy that raises temperature; the sun's keeps Earth warm.
3Step by step Steps
- Step 1: Meet the sun, our starThe sun is a star — a giant sphere that glows with its own light and heat, made mostly of blazing gas. It sits at the centre of the Solar System, big enough to hold over a million Earths. The sun streams light and heat into space, and the sunlight reaching Earth powers everything: plants photosynthesise, weather circulates, water cycles — all driven by the sun's energy. The sun is truly the power station of life on Earth.
- Step 2: Answer why the moon shinesThe moon gives no light of its own; it is just a satellite circling Earth. It looks so bright because it reflects sunlight: the sun lights the moon, and the moonface bounces the light to Earth into our eyes. So only the moon's sunward side is ever lit, and as the moon circles Earth, the lit share grows and shrinks, making the phases from new moon to full moon.
- Step 3: Know the eight planetsThe eight planets, nearest to farthest from the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The inner four are rocky and smaller; Jupiter is the largest, a gas giant; Saturn is famed for its beautiful rings; Uranus and Neptune lie far out, cold and dim. No planet shines by itself — all are seen only by reflecting sunlight.
- Step 4: See what makes Earth uniqueEarth sits at just the right distance from the sun, so temperatures are moderate and water stays liquid; Earth also has an atmosphere that gives us oxygen to breathe, softens the day-night temperature swing and blocks harmful radiation. Liquid water, air and a suitable temperature together make Earth the only planet known to nurture life. Seen from space, astronauts call it a blue marble — beautiful, precious, and worth protecting.
- Step 5: Know the galaxy and the vast universeWiden the view: the Solar System is but a tiny member of the Milky Way, a giant galaxy holding more than a hundred billion stars; the hazy band across the night sky is our inside view of it. The universe holds countless galaxies like ours, each with billions of stars, gazing at one another across distances counted in light years. So vast is the universe that it dazzles us — and reminds us how much we have yet to learn.
- Step 6: Admire the cosmos and cherish EarthHuman exploration never stops: telescopes see ever farther, probes have landed on the moon and flown past Mars and Saturn, and space stations host crews year-round. These missions deepen our knowledge of the Solar System and beyond. As we admire the cosmos, we must also cherish Earth — in the known universe it is the only home fit for us. Study your science well, and one day you may join the missions to the stars.
5Worked example Example
Example: On a stargazing night, Ying asks her father: the moon is not a star, so why is it so bright? Father points to a bright dot and says it is Jupiter — also not a shining star, yet visible. Answer for the father.
- First classify: the sun is a star that glows by itself; the moon is Earth's satellite and Jupiter is a planet — neither glows of its own.
- Why the moon shines: the moonface reflects sunlight, and the reflected light reaches our eyes, making it look bright and clear.
- Only the moon's sunward side is ever lit; the phases come from how much of the lit side faces us.
- Jupiter shines the same way, by reflecting sunlight; it is far nearer than the stars, so it looks like a bright dot.
- Conclusion: the glow of the moon and planets at night is all reflected sunlight.
- Answer: Neither the moon nor Jupiter makes its own light. The moon is Earth's satellite and Jupiter a planet; they look bright because they reflect sunlight off their surfaces into our eyes. Only the moon's sunward side is lit, creating the phases; Jupiter, much nearer than the stars, shows its reflected light as a bright dot. So their night-time glow all comes from the sun.
6Common mistakes Mistakes
7Quick check Quick check
Q1What kind of body is the sun?
Q2Why does the moon look bright?
Q3How many planets are in the Solar System?
Q4Which galaxy holds the Solar System?
Q5Which two forms of energy does the sun send Earth?
8Recap Recap
- The sun is a star, streaming light and heat energy.
- The moon and planets shine only by reflecting sunlight.
- Eight planets: Mercury to Neptune in order.
- Earth has liquid water, air and the right warmth for life.
- Our Solar System sits in the Milky Way, one galaxy among countless.