When we accept the evidence of our unaided eyes and describe the sun
as a yellow star, we have summed up the most important single fact about
it – at this moment in time. lt appears probable, however, that sunlight will
be the colour we know for only a negligibly small part of the sun’s history.
Stars, like individuals, age and change. As we look out into space, we see
around us stars at all stages of evolution. There are faint blood-red dwarfs
so cool that their surface temperature is a mere 4,000 degrees Fahrenheit,
there are searing ghosts blazing at 100, 000 degrees Fahrenheit and almost
too hot to be seen, for the great part of their radiation is in the invisible
ultraviolet range.
Obviously, the “daylight” produced by any star depends on its
temperature; today (and for ages to come) our sun is at about 10,000
degrees Fahrenheit, and this means that most of the sunlight is
concentrated in the yellow band of the spectrum, falling slowly in
intensity toward both the longer and shorter light waves. That yellow
“hump” will shift as the sun evolves, and the light of day will change
accordingly. It is natural to assume that as the sun grows older, and uses
up its hydrogen fuel – which it is now doing at the spanking rate of half
a billion tons a second – it will become steadily colder and redder.
Choose the correct answer from a, b, c or d:
1. Why are very hot stars referred to as “ghosts”?
a) They are short- lived.                    b) They are mysterious.
c) They are frightening.                   d) They are nearly invisible.
2. According to the passage, as the sun grows, it is likely to become ..................
a) red                      b) violet               c) orange                 d) yellow
3. What does the underlined pronoun “its” refer to?
a) Yellow humbs.  b) Day.                   c) The sun.              d) Fuel.
4. The daylight is clearly dependent on .................... .
a) sun colour     b) sun temperature c) sun growth           d) sun size
5. The underlined word “evolves” is a synonym of .................... .
a) develops          b) absorbs             c) rounds                  d) soaks
6. What is the main idea of the passage?
a) Faint dwarf stars                          b) The evolutionary cycle of the sun
c) The sun’s fuel problem                 d) The dangers of invisible radiation
7. All of the things on the sun are .................... .
a) easily reachable                         b) hard to be reached
c) invisible                                       d) visible
8. The sun is similar to the human because .................... .
a) it grows            b) it changes     c) it gets red            d) both a and b