Our Evolving Universe
Self Test 15

1. The easiest way to detect Earth-sized planets around normal main-sequence stars is
   1. direct observation
   2. observation of transits (planet crossing in front of star)
   3. Doppler shift observations
   4. non-existent (there is no way to detect such planets)
   
   
2. What aspects of the fossil record suggest that it is quite easy for life to evolve on the young Earth?
   1. most rocks contain fossils
   2. some of the oldest rocks contain fossils
   3. fossil organisms are so diverse that life must have originated more than once
   4. life evolved quickly from simple cells to complicated organisms
   
   
3. Hot blue main-sequence stars are unlikely to have life-bearing planets because
   1. the planets would be too hot
   2. the planets would be too massive
   3. the star would not live long enough for life to evolve
   4. the star would emit too much ultra-violet radiation for life to evolve
   
   
4. A spectroscopic detection of ozone in a planet's atmosphere is good evidence for life because
   1. an oxygen-rich atmosphere is not produced unless photosynthesising life is present
   2. life would not be present without an oxygen-rich atmosphere
   3. the ozone is needed to protect life on the planet from ultra-violet radiation
   4. oxygen atmospheres are characteristic of Earth-sized planets, not gas giants
   
   
5. As far as we know, signs of our own technological civilisation could be detected by aliens
   1. anywhere in the Galaxy, if their technology is advanced enough
   2. within about 50 light years, if their technology is advanced enough
   3. only if they visited the solar system
   4. only if we were to transmit a radio signal aimed at their star (or if they visited the solar system)

out of 5.

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