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Why's the Sun Red during Sunrise and Sunset?
As day breaks, a reddish-white ball of light that we call the sun, rises. This red haze gives way to a golden-white sheen as the day advances and reappears when the sun sets in the evening. Does the sun really change colours, or does it only seem so? The explanation lies in-between. Light from the sun consists of three kinds of radiation – ultra-violet rays, visible light and infra-red rays. Unlike visible light, ultra-violet rays and infra-red rays cannot be seen....
Why Do Stars Twinkle?
Watching stars on a moonless night can be an quite an interesting experience. As clusters of stars take familiar forms – of a bear, a man in armor wielding a sword, millions of other stars simply twinkle. As if they were playing hide and seek with one’s eyes. We all know that each star is actually like the sun. And the huge collection of stars on the night sky is like a collection of many, many suns....
What is the Weight of Air?
As you stand in the middle of a playground or while you are sitting in your class, there is an immense weight right over your head, but you do not feel it! This is the weight of the atmosphere, or air, as we know it. Composed of nitrogen, oxygen, carbon dioxide and other gases, it surrounds the earth like an envelope. And, it extends almost a thousand kilometres above the Earth’s surface. Like all other substances, air also has weight....
What is a Tornado?
If you ever happen to see a dark often greenish sky, wall cloud, large hail and a loud roar similar to a freight train then run to a safe place as it could be a tornado. Popularly known as twisters, tornado is derived from Spanish word ‘Tronada’ meaning thunderstorm and ‘Tornar’ meaning to turn. Tornadoes [Illustrations by Amarjeet Malik] A tornado is defined as a violently rotating column of air that can spin faster than 300 m....
What is the Ozone Hole?
On beaches as well as on the cricket ground, it is always possible to spot people with some kind of cream on their bodies or faces. Remember the South African pace bowler Alan Donald or ‘White Lightning’ as he is called, with “war-paint” on his face? No, it is not an attempt at camouflage, simply an effort to gain protection from the ultraviolet rays of the sun. And therein lies a paradox – it is the light and heat of the sun that sustains life on earth, but among its many friendly rays are some harmful ones as well....
Treaty on Global Warming
In the last week of July 2001, representatives from 178 countries met in Bonn, Germany, for something that is very crucial to their future and the very survival of our planet. They signed a historic agreement that promises to fight global warming. This is the first international treaty of its kind that seeks to check the excesses of human development at the cost of the environment – and the planet itself. Location and date marker for glacier in Jasper National Park in Canada....
Why is Snow White?
I am sure like my two kids, all of seven and three years, you too may find the cold in Delhi a bit too extreme. It is cold and clammy and some days it is foggy making it dangerous to drive. Some days I would like them to be adequately muffled up in warm winter clothing, while they feel quite comfortable running around in a sweater and shorts! But most days it was grumble, grumble, grumble!...
The Dark Kingdom of Uranus
Named after the father of the Titans in Greek mythology, Uranus is the seventh planet in the solar system. It was first observed through a telescope by Sir William Herschel on March 13, 1781. Although Herschel wished to call the newly discovered planet Georgium Sidus (Georgian Star) for King George III of England, Johann Bode’s proposal of the name Uranus gained more acceptance over the years and finally became universal in the mid-19th century. The Uranian realm is a dark kingdom, so remote from the sun that daylight there approximates a total solar eclipse on Earth....
The Earth Is Getting dimmer
If you have viewed a crescent moon on a clear night, you would have observed an eerie glow around the moon. This is called earthshine. Do you know why the moon glows? The eerie glow around a crescent moon is called earthshine. Our earth and the moon act as giant mirrors that reflect sunlight. Actually most objects reflect light. A mirror reflects almost all the light that falls on it. And an object that does not reflect light is called opaque....
Global Warming
Konish Biswas, a student of Standard VIII puts forth his views on a problem that is affecting the whole planet. Nowadays as you know, there is a lot of pollution in the atmosphere. The level of carbon dioxide and other such gases (known as greenhouse gases) is rising. These gases trap the heat and do not let it escape from the atmosphere. Global Warming [Illustration by Sudheer Nath] When the presence of these gases goes beyond a level, the temperature rises....
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