Unit Test
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Which best describes why Kepler's observation of planetary
motion is a law instead of a theory?
In the seventeenth century, astronomer Johannes Kepler
observed the planets revolving around our sun and analyzed
data about them. He found that as the distance from the Sun
increases, the amount of time it takes for the planet to go all
the way around the Sun increases. Even though Kepler did
not know why his observation was true, it has been found
that planets in all solar systems always revolve around suns
the same way.
It does not discuss independent and dependent variables
that can be observed or tested.
It does not provide an explanation for why the relationship
exists between distance and orbit time.
A lot of new technology has been developed that can
record more accurate data about planetary motion.
A lot of different understandings of why planets move
have been developed, and Kepler's provides the best
explanation
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scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.