What is a nebula? A nebula is a huge cloud of gas and dust in space. Some can be seen with the naked eyes but we can view more through a telescope. A nebula has mostly hydrogen gas and some helium. Sometimes the two gases...
Why do hailstones come in varying sizes? Hail is formed when raindrops pass through a belt of cold air and are frozen during their passage to earth. Single raindrops form small hailstones. Sometimes as the small hailstone falls it meets a rising current of air....
When did people begin to cook food? Except for frying, primitive people were familiar with the different types of cooking that are practised today like broiling, roasting, baking, stewing, steaming, parching and drying. But their cooking was more crude. Animals were roasted whole on a...
Who was Neanderthal man? Neanderthal men probably existed for about 70,000 years in central Asia, the Middle East and many parts of Europe. The men were stocky and had flat skulls. They had long faces with heavy jaws. They used tools like hand axes and...
Why do we need sunshine for good health? Sunshine can destroy fungi and bacteria that live on the skin. It causes the white blood cells which fight infections to become active. It also charges our nervous system by giving the muscles new tone. The ultraviolet...
What is fool’s gold? Fool’s gold is in fact a mineral known as iron pyrite. It is a yellow-coloured mineral with a brilliant shine and was often mistaken for flecks of native gold in rock. Native gold is often found in quartz veins and pyrites....
What are molluscs? Molluscs are animals without backbones. They include snails, octopuses, clams, oysters, etc. They can be found in the tropics as well as the Arctic and in sea or on land. Molluscs have soft, slimy and boneless bodies. The bodies have a covering...
What enables ducks to swim on water? The duck’s feathers have tiny projections called barbules which hook together and trap air between the feathers. The duck has air sacs connected to the lungs which help to hold air inside its body. The air between the...
How big are asteroids? Asteroids are big lumps of rock or ice. Most of these are only a few tens of kilometres across. The biggest asteroid is Ceres. It is about 1,000 km across. Ceres was discovered in 1801. Others like Pallas and Vesta are...
Which babies are carried piggy-back by their mothers? Like the kangaroo baby the joey, the koala bear too is carried in its mother’s pouch for the first six months after its birth. But after that the koala bear cub climbs on the mother’s back and...
