Almost all living things are sensitive to light. You know for example, that a clam closes its shell when a shadow falls across it. This action is made possible by a number of special cells lining the edge of the shell. Light falling on these cells excites them. Nervous messages or impulses then pass to […]
How hot is the sun? It’s that much hot that can flame or burn anything very easily. Can we imagine about the temperature and hotness of sun? No even we cannot imagine the real temperature of sun. The sun is the largest member of our planetary system. It weights about five hundred times more then […]
Eyes do not stay still. They are constantly moving, following objects, looking from place to place. Our eyes and the eyes of other mammals, move together. Both of them are always directed toward the thing we wish to see. The delicate control of eye movements depends on nerve impulses from a special centre in the […]
To the ancient shepherd or early astronomer, a star was but a flickering point of light in the sky, seeming almost about to be blown out by every passing breeze. Some thought of the stars at little glittering gems set in the solid dome of the sky. Only after many weary centuries had rolled past […]
During the Great War, a pamphlet was issued in the army. With the title (in what was called Roman Urdu) Is makhi KO maro. The army authorities had been encouraged to publish this by the fact that many soldiers were suffering from dysentery, typhoid and stomach complaints. Most of those troubles arose from food and […]
When we speak of the sky, we usually mean the vault of the heavens, or the great arch which seems to lie like an inverted bowl over the earth. We say that the sky is blue, that there are thunder clouds in the sky or that the sky looks stormy or clear. In this sense […]
The sky appears blue to us because the light from the sun is broken up and scattered by the tiny particles of air, dust and water vapor in the atmosphere. Sun light like all white light is made up of all the colors of the spectrum, the same colors we see in the rainbow. If […]
No one knows how many stars there are in the whole sky. No one knows, either, how far the sky extends in all directions away from the earth. This is of course, the same thing as saying that no one knows how large the universe is. With each new telescope larger then the last, astronomers […]
In the early days, before it was understood much about the heavens and the science of astronomy, many people believed that the stars actually cease to shine during the daytime. The ancient Egyptians believed that they were lamps lighted each night by the gods, so that the sky would be more beautiful. They thought that […]
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