The gravitational pull of each planet basically tries to pull everything within its field toward the planet’s centre, including the planet’s own mass. As all areas of a planet are being pulled equally toward the centre, the planet takes a spherical shape, with all points on the surface being more or less equally distant from the centre.

Only the metals iron, nickel, cobalt and some of their alloys can be made into strong magnets. However, an electric current also gives a strong magnetic field when if flows through a coil. The Earth has magnetic field too, probably because of electric currents circulation in its core. There is a connection here. The atoms of which all substances are …

When it rains, the outer soil of the earth absorbs it. Some water is evaporated and some is absorbed by roots of the trees and plants. The remaining part of the water goes downward due to gravitation. It goes as far below as the openings and cracks of rocks will permit. There is a zone below the surface of the …

Regular scheduled voyages on a set route on the sea are called ‘line voyages’ and vessels (passenger or cargo) trading on these routes to a timetable are called liners. In older usage, ‘liner’ also referred to ships of the line, that is, line-of-battle ships, but that usage is now rare. Today, the term refers to a ship that is constructed …

Ice-skate blades are made of steel for three reasons. First, because steel is immensely strong, hard and resistant to wear. Second, because it is a relatively low conductor of heat. And third, because it can be sharpened to a keen edge. A skate blade has to resist tremendous pressure because it is hollow-ground, so that only the edges rest on …

In the earliest days of life on Earth, hands helped man when he stood or walked about. They were used much as an ape uses them now. If we put our hands on a table as if about to walks on the tips of our fingers, we can see what a well-balanced support is formed. We no longer need our …

Have you ever climbed a tree and peeked into the nest of a crow or a sparrow? Or looked into that flowerpot where the noisy pigeon decided to lay its eggs? The sight of a mother hen sitting on a bunch of fresh white eggs is great, though most of us see them only when they land on the breakfast …

Although the human eye is sensitive to yellow and green, it has become a tradition to use red as a signal for caution. A ship carrying explosives would have a red flag flying to signal to other ships not to come very close. Experts believe that since the deep red colour of blood could shock people into alertness, such a …

A cloud is a mass of water droplets formed when air above the surface of the earth is cooled below the dew-point. As clouds float through the cool air above the earth they often hit areas where the air is warmer. The parts of the cloud touching the warm air then evaporate, leaving the cloud with a new shape. Winds …

Celestial bodies are spherical in shape because of gravity. Whenever enough mass gathers close together, the resultant gravity, which follows the inverse square law, pulls equally in all directions and results in a spherical shape. Irrespective of the material composition of the celestial body, a diameter of a few hundred kilometres is sufficient to create a spherical form.