Because the html format does not always appear the same to each viewer unlike in a normal TOEFL reading passage the words will not be referred to by line, instead they will be in bold and italisicized type with the number of the question inside parentheses.
Red dwarfs are smaller, (Q.2)dimmer, and cooler than our sun. There are more than a dozen of these stars within a few light years of our Earth, yet not one of them is visible to the naked eye. For years it was thought that they were a poor place to look for alien lifeforms. However, recent computer models contradict this supposition. This is excellent news for xenobiologists since four out of every five stars is a red dwarf.
The argument against life being present on the planets orbiting around red dwarfs was twofold. First, these stars are so faint because they begin with ten to sixty percent less mass than the sun. They are frugal: their nuclear reactions are far slower than in other types of stars. This (Q.5) stinginess could be a point in their favor since the average lifetime of a red dwarf is one hundred times that of the Sun, which would allow life a much longer time to evolve. Although with so little energy available how could there be life? Living organisms as we know them depend on a range of temperatures where water is liquid. A planet orbiting a red dwarf at the same distance as our planet orbits the Sun would be a frozen ball of ice. Of course, you could simply place the planet closer to the red star, hence it should be warmer and habitable.
But that is the second problem; a closer orbit comes with a cost. A planet that is (Q.6) nestled next to the star would always present one face towards the star, very much like our moon does to the Earth. So one side would be a blast oven and the other an icy circle of hell. Not so, according to and Manoj Joshi at NASA's Ames Research Center. When they ran a computer simulation of such a planet they found out that if the planet had an atmosphere only about 15 percent thicker than ours the results implied that it could shelter life. Venus already has an atmosphere ninety times that of Earth's so a slightly denser atmosphere is well within the realms of possibility. A more abundant atmosphere would transfer enough heat from the eternal sunny side to endless night. The temperature range was inside acceptable norms: from 50 degrees to minus 50 degrees Celsius.
Another difficulty presents itself with this scenario since water would tend to migrate from the hot side to the frigid dark side. However, Martin Heath of Greenwich Community College, London thinks he might have the solution to this dilemma. He postulates that if the oceans are deep enough, water will circulate back from the nether regions over to the hot side. Under a deep ice cap, sea water would be insulated from the intense cold and remain liquid and thus be able to freely disperse.
While this type of planet might
be able to bear life,
the conditions would be (Q.9) strikingly dissimilar
we find on Earth. One important fact to remember is red dwarfs emit a
deal of their energy in the infrared. Which could offer some problems
the process of photosynthesis. In addition, red dwarfs
massive starspots than Sol which could reduce incoming light by up to
fifths. Starflares also pose a problem since they can brighten a red
by as much as one hundred percent. Besides these global changes, life
have to deal with the variety of fixed temperatures on this planet.
zero in the hot zone would be centered on the equator where the star
be directly overhead. The rim of eternal shade would be somewhere
zero degrees and cooler the deeper you went until you reached
of minus fifty degrees centigrade. Since the sun would be stationary in
the sky, the backside of a hill would be in perpetual shadow, as well.
This continuous light vs constant shade would certainly produce