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Ever since it was known that the planets were bodies more or less like the earth, people
have asked: "Are there living things on them, too?". This is hard question to answer, but by
combining the resources of most of most of the sciences, we can give a rather good answer.
First let us consider life on our earth, All living things2 are absolutely dependent on
water. Moreover, this water must be liquid-neither ice nor gaseous water vapour3, but
ordinary liquid water. Nothing grows while it is frozen. And no living thing would survive if
the water were boiled out4 it. Hence it is necessary that the temperature on a habitable planet
should be above freezing part of the time, and below the boiling point all the time.
Light is necessary too. Practically all the food in the world is produced by green plants.
Plants get the energy they require for their growth from sunlight.
There is good reason to believe 8 that the vast store of oxygen5 in the air has all been
supplied by plants. If there were no plants, there would be no food to eat, nor oxygencontaining air to breathe.
If we inquired whether other planets were habitable, we should then try to find out
whether their temperatures were suitable for life, whether they had water and atmosphere on
them, and if so, whether oxygen and carbon dioxide were present.
Measurements of planetary heal? have shown that Mercury, which is the nearest planet
to the sun, has a noonday temperature7 of about 3270 Centigrade For the remoter planets the
temperatures range from 150 0C to 2000C below zero. All these planets are evidently
unhabitable by any form of life known to science.
Пояснення до тексту
1. Are planets habitable! - чи придатні планети для життя!. 2. Living things - живі істоти.
3. Neither ice nor gaseous water vapour – ні лід, ні водяна пара. 4. To boil out - википати.
5. Vast store of oxygen - великий резерв кисню. 6. Planetary heat - тепло (температура)
планети. 7. Noonday temperature - температура середини дня (полудня). 8. There is good
reason to belive – є усі підстави вважати.
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