Look at the sky at night. How many stars can you see ? ___1___
say that we can see about 2500 stars with the naked eye. But of
course we can see more if we use a pair of ___2___
or a telescope. In fact, we can see billions of stars ___3___
a powerful telescope. What are these stars ? Our ___4___
is a star; all the stars are actually suns. The sun ___5___
much bigger than the other stars because of its distance. It may
be the nearest start ___6___
the earth, but it is actually 150 million kilometers from us. It
takes eight minutes for the light from the sun to ___7___
us.
The surface temperature of the sun is 6000 oC, but
its ___8___ is very, very
much higher. It is thought that the center has a ___9___
of 14000000 oC. Many of the stars are ___10___
than the sun and have surface temperatures reaching 10000 oC
___11___ the coolest one is
close to 2600 oC.
It is interesting ___12___
note that the stars have various colors; blue, white red, orange
or yellow. The hottest stars are blue ___13___
the coolest are red. The brightest star in the sky is Sirius
which is a white star. |