The sky is pale blue in higher altitudes while it is deeper blue in lower altitudes. This is because there is more air molecule closer to earth surface (as a result of higher air pressure) than higher altitudes. The air molecules are responsible for scattering of sunlight hence giving the sky its blue hue. The more the air molecules the more the scattering.
Answer: Plastic waste and industrial effluent too choke India's holy river. But the most serious long-term threat to the Ganges is lack of water. For many years, the flow of the river has been ebbing. Activists blame most of the deficit on unsustainable extraction.
Explanation:
I thought you were asking what comes after 23 );
Earth is the 3rd closest.