"The Dying Sun" is an essay by the British astronomer Sir James Jeans. He shows how tiny and lonely our earth is in a vast universe, explains how he believed the planets were formed (a passing star tore a tidal mountain off the sun), and argues that life needs a narrow band of temperature that is extremely rare in space.
This lesson is from Book II (Modern Prose) of the Punjab 2nd Year English course. Below are model answers to the questions at the end of the lesson, written the way examiners like them: point first, then evidence from the text.
Summary
Stars are as many as the grains of sand on all the seashores of the world. Most are so large that hundreds of thousands of earths could fit inside them. They travel mostly alone: in a scale model where stars are ships, the average ship is well over a million miles from its neighbour. About two thousand million years ago, Jeans writes, a wandering star came near the sun, raised a huge tidal mountain and tore it to pieces. The pieces became the planets. One of them, our earth, cooled until life began. Life needs a temperature at which substances can be liquid, found only in narrow belts around stars, and probably only one star in 100,000 has a planet at the right distance.
Questions and answers
1. How is it that a star seldom finds another star near it? The universe is so immense that most stars travel alone, like ships on an empty ocean. In a scale model where the stars are ships, the average ship is well over a million miles from its nearest neighbour.
2. What happened when a wandering star came near the sun? Just as the sun and moon raise tides on the earth, the wandering star raised huge tides on the surface of the sun.
3. What happened when the wandering star came nearer and nearer? A tidal mountain rose higher and higher. Before the star moved away, its pull became so powerful that the mountain was torn to pieces and small parts were thrown into space.
4. What are planets and how did they come into existence? Planets are the pieces of the sun that go round it. About two thousand million years ago a wandering star raised a huge tidal mountain on the sun; its pull tore the mountain to pieces, which have circled the sun ever since. Our earth is one of them.
5. Why is there no life on the stars? The stars are far too hot. Close to them the temperature is thousands of degrees, at which all solids melt and all liquids boil.
6. Write a note on the beginning of life on the earth. The pieces thrown off by the sun were at first too hot for life. They slowly cooled, and in time one of them gave birth to life in simple organisms that could reproduce before dying. From these humble beginnings life grew more and more complex, up to human beings with feelings, ambitions and a sense of beauty.
7. Why is the universe so frightening? Its distances and stretches of time are too great to imagine and make human history seem very small. We are lonely, and our home is only a millionth part of a grain of sand. Above all, we find no sign of life like ours anywhere except on the earth.
8. What conditions are necessary for life? Life needs suitable physical conditions, above all a temperature at which substances can exist as liquids. Such temperatures are found only in a narrow belt around each star; all these belts together are less than a thousand million millionth part of space, so such conditions are extremely rare.
A note on the science
Jeans wrote this around 1930. Scientists today think the planets formed from a disc of gas and dust around the young sun, about 4,600 million years ago. In the exam, answer from the text; it is still good to know that science has moved on.
Common mistakes in the exam
- Saying the moon tore the sun apart. The moon is only Jeans's comparison; it was a second, wandering star.
- Calling a planet a star. A planet gives no light of its own.
- Mixing up the numbers: one star in 100,000; over a million miles; two thousand million years.
Quick revision
- Stars: countless, huge and lonely.
- Planets: pieces torn from the sun by a passing star (Jeans's account).
- Life: needs liquid-water temperatures, found only in rare, narrow belts.
For key ideas, an interactive timeline of the planets' birth and MCQs with reasons, open the free lesson The Dying Sun.