Huge amounts of polluting gases are being released into the earth’s atmosphere by the large scale burning of fossil fuels or natural fuels found under the earth. These gases are the main culprits behind the phenomenon of global warming and other climatic changes. In order to find cleaner fuels, scientists around the world are trying to find a fuel or …
Read More »How can we talk to the stars?
If other beings existed in space, we could talk to them via radio waves, which travel at the same speed as light. Astronomers have begun t listen for possible incoming radio messages from the stars, although nothing has been heard so far. In 1974 the first deliberate radio message from Earth was beamed towards as star cluster called M13 in …
Read More »How can we see heat?
You may not know it, buy your body is giving off heat rays. So is everything else around you. The strength of these rays, which are also known as infrared rays, depends on how warm or cold things are. Special cameras and instruments can pick up these heat rays and turn them into pictures. In this way, it is possible …
Read More »How can ice shape the land?
The surfaces of valley glaciers are littered with rocks which have tumbled down the mountainsides. Other rocks are frozen into the sides and bottoms of glaciers. These rocks turn the glaciers into gigantic files, because, as the glaciers move, the rocks scrape away at the land and gouge our more and more rocks. When the ice melts, steep sided, U-shaped …
Read More »How big is the biggest diamond in the world?
Diamonds are measured in Carats (not carrot). A carat weighs 0.2 grams. The largest fine quality, colorless diamond ever found was called “The Cullinan”. It was mined in South Africa and weighed 3,106 carats. It was cut into 106 jewels and produced the finest, largest gemstone ever, weighing 530.2 carats.
Read More »How astronauts urinate in space?
When American astronaut Alan Shepard couldn’t hold his pee any longer on their space mission in 1961, he was directed to do it in his suit, a new book has revealed. According to Tom Wolfe’s book ‘The Right Stuff,’ that’s what mission control said to Shepard during Mercury-Redstone 3, when the astronaut said he needed to urinate. Shepard did as …
Read More »How are waterfalls formed?
Many waterfalls occur where rivers flow over hard rocks which overlie softer ones. The hard rocks resist erosion, while the softer rocks are worn away. The hard lip of the waterfall often overhangs the softer rocks and slabs of hard rock sometimes break off and crash downwards. In this way, waterfalls, like southern Africa’s Victoria Falls (whose African name means …
Read More »How are ultra-violet rays blocked by the ozone layer?
The ozone layer contains ozone molecules – O3 molecules – which are formed by the action of ultra-violet rays on atmospheric oxygen. This oxygen, which is O2, converts into O3 when UV rays fall on it. When these rays fall on the surface of the atmosphere, they are absorbed in the conversion of oxygen into ozone. As a result, ultra-violet …
Read More »How are the maximum and minimum temperatures of a place fixed?
Maximum and minimum temperatures are measured using thermometers mounted inside a wooden box with slits, called Stevenson’s screen, which is generally kept facing north. The maximum thermometer is mercury-in-glass – as the temperature rises, the mercury expands and moves freely up a constriction in the thermometer. When air temperature drops, the constriction prevents the mercury from flowing back due to …
Read More »How are the ages of rocks measured?
In the 19th century, geologists could tell whether one rock layer was older or younger than another by the fossils they contained. But they could not measure the absolute ages of rocks until after the discovery of radioactivity in the 1890s. Radioactive substances, which are occasionally found in rocks, give off high-energy rays and decay (break down) at a fixed …
Read More »