Why were the Pyramids built?

The Pyramids were built as tombs for the pharaohs of ancient Egypt.

The early kings, or pharaohs, were buried in tombs inside roughly built stepped pyramids. The greatest pyramids came later. The largest is that of the pharaoh Khufu (also called Cheops) at Giza. Over two million blocks of stone were needed, each dragged into place by hundreds of slaves.

Inside the burial chamber, the pharaoh's body, preserved as a mummy wrapped in cloth, was buried in a stone tomb. Around him were food, clothes, weapons: everything that he might need in the next world.

Why cannot I fly?

You cannot fly because the force of gravity pulls you down. In order to fly, the force of gravity has to be overcome. Birds, bats and insects can fly because they can overcome gravity.

Why do we say that the optical telscope drew a new picture of the Universe?

The telescope was a very important discovery in astronomy, and astronomers discovered that if more light reached the eyepiece of a telescope, the image would be much brighter. So, they made the lenses and mirrors of their telescopes bigger, so as to capture as much light as possible, and focus it on a single point.

Optical telescopes have lenses in them that collect light from objects in the sky. These lenses focus the light, by either bending it or reflecting it to form an image. There are two different designs of optical telescopes - refracting telescopes and reflector telescopes. An optical telescope forms images of faint stars and other objects that are very far away, so as to give the observer a clearer picture of the Universe. This type of telescope can gather many times the amount of light that your eye can.

Why did Copernicus revolutionize concepts about the Universe?

Copernicus is said to be the founder of modern astronomy. His investigations were carried on quietly and alone, without help or consultation.

He made his celestial observations from a turret situated on the protective wall around a cathedral. His observations were with just his eyes, as a hundred more years were to pass before the invention of the telescope.

In 1543, Copernicus published a book about a new idea he had. Most people in his day thought that the Earth was at the centre of the Universe. They thought that the stars were little holes in a glass ball that surrounded the Earth. But, Copernicus disagreed. According to him, the Universe is not centred around the Earth, but that the Earth is actually a planet circling the Sun. Not many people liked his book or his ideas, for they went against the philosophical & religious beliefs that had been held during the medieval times. Copernicus died in 1543, and was never  to know what a stir his work had caused. Of course, we know today that Copernicus was right!

Why did ancient astronomers observe the sky?

Beginning around 600 BC, ancient philosophers and scientists developed a number of important astronomical ideas by simply observing the sky, since they didn't have any modern tools or instruments to tell the time, location of a place or the nature of the Universe.

The ancient Greeks were able to figure out the shape and size of the Earth by calculating the height of the Sun or the stars. About 230 BC, Eratosthenes estimated the size of the Earth by using the Sun as a reference point. The sundial was another simple tool that depended on the Sun to let people know what time it was.

Sailors at sea used the stars above to guide them. In fact, Many early tribes of Polynesia and New Zealand have sailed great distances using the stars for navigation. The sun's position in the sky also allowed sailors to determine the latitude at which they were sailing. Another instrument called the 'qiblah' used the sun to find the direction of Mecca, so that Muslims could face in that direction for their daily prayers. So, you see ancient astronomers had many good reasons, to watch the sky, the Sun, stars and the Moon, day and night.

How did the ancient astronomers pictured the Universe?

The ancient astronomers pictured the Universe from the point of view of an observer on Earth. In fact, to them, the Earth was the centre of the Universe, and they believed that above it was a shining dome that was sprinkled with thousands of shining little lights that were the Sun, the Moon and the stars.

Later, the Greek astronomer Pythagoras suggested that the Earth might be a sphere, but he still thought that it was the centre of the Universe. It was only in 1543 that an astronomer named Copernicus suggested that the Sun might be the centre of the Universe. It was with the discovery of the telescope that Man finally developed a better picture of what the Universe is really like.

Why did astronomy spread and grow?

The earliest atronomers were priests and holy men, studying the movement of celestial bodies to chart celebrations and planting cycle. Their knowledge and theories of the Universe spread through two routes - trade and war. As great empires expanded, their gods, cultures, and learning influenced other cultures as well.

The ancient Babylonians were amongst the first to start developing theories about the design of the Universe. The Greeks and Romans later adopted the Babylonian system, replacing the names with the names of their own Gods. The earliest astronomical records are in the form of clay tablets that have been discovered in what was once Mesopotamia.

Early observers of the heavens realized that the repeated motions of the Sun, Moon and stars could be fashioned into a clock to tell the time of the day, and a calendar to mark the progression of the seasons. Many of the ancient monuments, in fact, show some of the features of an astronomical observatory.

Did you know that the earliest observatory to have survived is in Korea? It is a simple beehive structure with a hole in the roof.

Why is the astronomy called the first science?

Astronomy, or the study of the stars, began as a science only about 2,500 years ago, though people have been gazing at the heavens for millions of years. In the beginning, Man had only a few crude hand tools. Using these tools, and some mathematical calculations, he tried to find some explanation for the changing seasons, the floods, the droughts, sunrise, sunset, and all the other mysteries of nature.

Some of these explanations were very primitive and strange. But they are important, because they made people think and ask, and it is this spirit of curiosity that replaced imaginations with scientific observation and reasoning. This is why astronomy is called the first science.

Why are there many myths about the creation of the Universe?

Haven't you often wondered how this Earth and our Universe began? Well, this question has fascinated Man for millions of years, and different cultures and civilizations developed their own myths to answer this question. The ancient Egyptians, for example, believed that the Universe was created when the God Atum uttered his own name. Next, he vomited up his brother and sister, and they had two children together called Geb, who was the Earth, and Nut, who was the sky.

The Chinese believed that the Universe began with a huge egg, and within it, two forces known as ying and yang created the God Phan Ku, who in turn became the Universe.

The Hindus have several creation myths. One of these myths states that Universe began when the ocean gave birth to a golden egg from which Brahma, the creator of the Universe emerged.

The Aztecs of Mexico had a rather violent myth. They believed that the Universe was created when a goddess was ripped apart by two other gods creating the Earth and the sky!

According to the Christians, God created the Universe in six days, and rested on the seventh day. Today, of course, science has other explanations for the origin of the Universe, but you must admit that the old myths are really fascinating.

What are cosmic rays?

Cosmic rays are tiny particles that slam into the Earth's atmosphere at various levels of energy. Billions of cosmic rays are slamming into the Earth every second, most of them with a quite low energy. Although they are called 'cosmic rays', it should be noted that cosmic rays are point-like atomic particles. They are called cosmic rays because they are found everywhere in the Universe.

Astronomers believe that cosmic rays reach their high speeds because of the action of magnetic forces in space. There are two types of cosmic rays - primary and secondary. Their study provides scientists with information about the structure, operation, and history of the galaxy and of the Universe.