Recent developments in astronomy have made it possible to detect planets in our won Milky Way and in other galaxies. This is a major achievement because, in relative terms, planets are very small and old not emit light. Finding planets is proving hard enough, but finding life on them will prove infinitely more difficult. The first question to answer is whether a planet can actually support life. In our won solar system, for example, Venus is far too hot and Mars is far too cold to support life. Only the Earth provides ideal conditions, and even here it has taken more than four billion years for plant and animal life to evolve.
Whether a planet can support life depends on the size and brightness of its star, that is its 'sun'. Imagine a star up t twenty times larger, brighter, brighter and hotter than our own sun. A planet would have to be a very long way from it to be capable of supporting life. Alternatively, if the star were small, the life-supporting planet would have to have a close orbit round it and also provide the perfect conditions for life forms to develop. But how would we find such a planet? At present, there is no telescope in existence that is capable of detecting the presence of life. The development of such a telescope will be one of the great astronomical projects of the twenty-first century.
It is impossible to look for life on another planet using earth-based telescopes. Our own warm atmosphere and the heat generated by the telescope would make it impossible to detect objects as small as planets. Even a telescope in orbit round the earth, like the very successful Hubble telescope, would not be suitable because of the dust particles iron solar system. A telescope would have to be as far away as the planet Jupiter to look for life in outer space, because the dust becomes thinner the further we travel towards the outer edges of our own solar system. Once we detected a planet, we would have to find a way of blotting out the light from its star, so that we would be able to 'see' the planet properly and analyze its atmosphere. In the first instance, we would be looking for plant life, rather than 'little green men'. The life forms most likely to develop on a planet would be bacteria. It is bacteria that have generated the oxygen we breathe on earth. For most of the earth's history they have been the only form of life on our planet. As Earth-dwellers, we always cherish the hope that we will be visited by little green men and that we will be able to communicate with them. But this hope is always in the realms of science fiction. If we were able to discover lowly forms of life like bacteria on another planet, it would completely change our view of ourselves. As Daniel Goldin of NASA observed, 'Finding life elsewhere would change everything. No human endeavor or thought would be unchanged by it."
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1. This is a major achievement because, in relative terms, planets are very small and old not emit light.
in relative terms: relatively；relative: comparing to other things, 相对的。如：
Since I got a job, I have been living in relative comfort.
In relative terms, Britain was weak in the 20th century. (It was stronger before, but weaker in the 20th century.)
Relatively few people are prepared to sacrifice up to a third of their holidays for the pleasure of traveling on a ship. (NCE3 Lesson44)
2. Finding planets is proving hard enough, but finding life on them will prove infinitely more difficult.
infinitely more difficult: a lot more difficult。我们再来看infinitely的一些用法：
infinitely great: extremely great infinitely better: much better
Wives tend to believe that their husbands are infinitely resourceful and versatile. 妻子倾向于认为丈夫足智多谋、多才多艺。(NCE3 Lesson46)
3. The first question to answer is whether a planet can actually support life.
support：to provide the necessary conditions so that life can exist（本文中）。More examples:
His brother supported him while he was at college. (support: to provide a living for sb, 养活某人)
The land is so poor that it cannot support any crops. (support: to provide the necessary conditions for crops to grow)
4. Imagine a star up to twenty times larger, brighter and hotter than our own sun.
up to: as much as or no more than，至多，多达，直到。More examples:
Up to three hundred people were on board the ship. 船上多达300人。
We teach learners up to intermediate level in our centre. 我们中心将初学者教到中级水平。
I know nothing about it up to now. 直到现在我对此事还一无所知。
Relatively few people are prepared to sacrifice up to a third of their holidays for the pleasure of travelling on a ship. (NCE3 Lesson44)
5. A planet would have to be a very long way from it to be capable of supporting life.
be capable of: having the ability to do sth. More examples:
His wife is a very capable woman.
When he's drunk he's capable of saying rude things. ( He is more likely to say rude things.)
6. At present, there is no telescope in existence that is capable of detecting the presence of life.
in existence: that exists now. 现存的。如：
presence: being present in a place, 出席，到场，存在。如：
He is usually quite polite in my presence.
The contract was signed in the presence of two witnesses.
7. Once we detected a planet, we would have to find a way of blotting out the light from its star, so that we would be able to 'see' the planet properly and analyze its atmosphere.
blot sth out: cover or hide (writing, etc), 涂去（字迹等）；hide sth completely, 庶蔽；remove or destroy (thoughts, memories, etc) completely, 消除或抹掉（思想，记忆等）。如：
Several words in the letter had been blotted out.
A dark cloud suddenly blotted out the sun.
analyse v. 分析，分解 analysis n. 分析，分解 analytical adj. 分析的，分解的。如：
His report analyses the effect of the policy upon middle class families.
8. In the first instance, we would be looking for plant life, rather than 'little green men'.
in the first instance: in the first place, 首先 for instance: for example. 如：
In the first instance, we had better make sure the calculations are correct.
A Frenchman, for instance, might find it hard to laugh at a Russian joke. (NCE3 Lesson29)
We hope you would meet our requirements in this instance. ( in this instance: in this case, in this situation)
9. As Earth-dwellers, we always cherish the hope that we will be visited by little green men and that we will be able to communicate with them. But this hope is always in the realms of science fiction.
cherish the hope: 抱有......希望，如：
Like a scientist bent on making a discovery, he must cherish the hope that one day he will be amply rewarded. 就象一个决心要有所发现的科学家一样，他必须抱有有朝一日能如愿以偿的希望。(NCE3 Lesson34)
the realms of science fiction: the fields covered in since fiction
realm: kingdom, 王国；a certain field or area, 领域。如：
In a realm as large as medieval Germany, the king faced a huge task.
She found great pleasures in the realm of history.
10. No human endeavor or thought would be unchanged by it.
endeavor: n. effort or attempt, 企图，努力；v. try, 试图，竭力。如：
Crossing the North Pole on foot was an amazing feat of human endeavor.
Engineers are still endeavoring to locate the source of this problem.
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