The stars are so far away from us that astronomers do not normal measurements such as kilometers or miles. Instead, they have invented a unit called the light year. This is the distance traveled in one year by a beam of light, which moves at the fastest speed in the Universe, 300,000 km (187,000 miles) per second. A light year …

The Secretary bird prefer to walk around looking for its prey rather than to fly. As a result its feet are less adapted for killing. The Secretary bird strides around African grasslands on its long legs hoping to disturb its prey. It catches insects, small mammals and lizards, but it is best known for eating snakes. It attacks a snake …

In stormy weather, powerful waves hurl loose rocks at the shore, undercutting cliffs. While soft rocks are worn back to form bays, hard often survive as headlands in which waves then hollow out caves. If the roof of a cave collapses, a ‘blow hole’ is formed in the ground above. When waves break in the cave, clouds of spray burst …

Most people are familiar with the idea of the sea eroding or destroying land. For example, storm waves can remove rock from many coasts. Some loose rock is swept out to sea, but some is moved along the shore. Groynes, or sea walls, which jut out from the coast in many resorts, are built because of this movement. Without them, …

On hot days at the seaside, cool breezes blow inland from the sea. This is because lands warm up faster than water. Hot air over the land rises, and cool air from the sea is sucked in. At night, the reverse happens, because the land cools faster than water. In this way, the sea moderates the climate of coastlands. Ocean …

Hybrid engines use two or more power sources. They consist of a usual fuel engine, complemented by a pollution-free engine, an electric engine for example. The fuel engine and brakes are used to recharge the batteries for the electric engine, eliminating the need to plug in while unused. When brakes are applied, some of the energy being used to stop …

Nine ‘o’ clock. It’s time for your favourite serial on television. Have you ever wondered how the same serial can be viewed by millions of people across the world? This is possible because of satellite television technology. It uses man-made or artificial satellites to send your favourite serial to your television set. But why do we need satellites for this …

A cool glass of water topped with huge chunks of ice is sure to quench your thirst on a hot summer day. But, before you guzzle the water, look at how the ice floats on the water surface. How do these large ice pieces manage to stay afloat? Ice floats because it is less dense than water. (If you take …

Frost is frozen moisture. It forms when invisible water vapour in the air changes directly from a gas-like state into ice crystals. In mountains, moisture in cracks in rocks freezes at night. Because ice occupies more space than water, the ice exerts a wedge like pressure inside the cracks, widening them until the rocks split. This is called frost action.

Remember walking to the school or the bus stop on a cold wintry morning? You can see the beautiful crystal drops of dew, and if you happen to be on the grass, they could well be soaking your shoes. Ever wondered why there is no dew in the summer or rainy seasons? Well, special as it looks, dew needs special …