(1)At first, people (THINK) ________ the sky was blue because there were water droplets in
it, but if that were true you (GET) ________ a deeper blue when the air is more humid and
that's not the case.
(2) After a little more investigation, it (REALISE) ________ that the blue was
due to the air molecules in the atmosphere.
(3) The light from the sun is made up of
many different colours, each of which is a different wavelength of light.
(4) The
wavelength of red, for example, is longer than the wavelength of blue.
(5)
(LONG) ________ wavelengths for the most part travel straight through air molecules, while
shorter ones are more scattered by (THEY) ________ .
(6)
So when the blue wavelengths hit the air molecules, they are scattered all over
the sky ‒ and that's what you see when you look up.
(7)
At sunset, when the sun is lower on the horizon, its light has (TRAVEL) ________ through
many more air molecules than when it is right above us.
(8) All these molecules scatter
the red wavelengths, too, and that's why the sun (LOOK) ________ red at the end of the
day.