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How many of us look up at the sky after sunset ? Look up and realize how small and insignificant we are and how marvelous are God Creations. The sky is studded with jewels, yes with stars and other heavenly objects. Atheists may disagree. they think that everything comes and exists of its own.

When you look up at the sky on a clear night, the star studded heavens seems to form a vast dark dome over your head. It is the same every where on earth. Our planet seems to be surrounded by a limitless celestial sphere and the stars appear to be fixed to the inside of this sphere. As time goes by the stars seem to wheel over your head and the sphere seem to be spinning around the earth. At first there is little to distinguish individual stars and they seem to be scattered around the dark dome of the heavens. Some are bright and they stand out like beacons, others are so dim you can scarcely make them out.

In your mind you can group together some of the bright stars to make patterns. And night after night you will be able to find these same patterns in the sky. Even though the stars appear to wheel over head every night, they move together bodily-they do not change their relative positions in the sky in their patterns, we call them as constellations.

The stars are seen to be fixed in position inside the celestial sphere. This is why they are often called the fixed stars. But there seen to be a few notable exceptions to this general observation. Occasionally some bright objects can be found wondering around the celestial sphere among the fixed stars of the constellations.

But appearances are deceptive. We know that there is no great enveloping dark celestial sphere surrounding the earth. The darkness of the sky is the profound blackness of empty space (which is not really empty !) extending for distances so vast that as to be beyond our human comprehension. The tiny pinpoints of light visible as stars are in reality huge globes of incandescent gas that power our enormous amounts of energy in to space as light, heat and other forms of radiation. They are distant suns. As for the wandering objects, they are not stars at all but much smaller, closer bodies called planets.

Two to three thousand years ago people believed that the earth was the centre of the universe. They also believed that the sun, the moon and the planets all circled the earth, as did the fixed stars inside the celestial sphere. This was the classic Greek concept of the universe elaborated by the last Greek thinker Ptolemy.

ptolemy

The era was masked by the fabulous fantastic tales of Greek mythology. In ancient Greece astronomy and mythology intermingled and the heavens became the immortal resting place for a host of mythological characters that were embodied in the constellations. But we know them today not by their Greek names, but by their Latin ones.

The ancient Chinese, Indian, Egyptian and Mesopotamians were systematically studying the skies and keeping records of their observations. In later centuries similar activities were carried out by the cultures of the New World that flourished in Mexico, most of central America and in the South American regions which we call as Bolivia and Peru. Thanks to their systematic observations carefully made after a long time, the ancients were able to detect many regularities in the motions of heavenly bodies and to become quite skilled to predicting certain astronomical events such as eclipses. Even today some of the ancient eclipse observations are useful in helping astronomers determine the rate at which the earth’s rotation is showing down.

With the decline of the Greek and Roman civilizations by about the fifth century, Europe slipped in to a period of general cultural stagnation where much of the knowledge of the ancient world was either lost or forgotten. The period was known as the dark ages. Fortunately astronomy continued to revive elsewhere, particularly Arabia. One of the triggers was the translation in to Arabic of ptolemy’s work Alnaugest. This inspired generations of Arab astronomers until 1428 when Urugh being established at Samarkad the finest observatory of the times. The Janbha Mandir at Delhi was equally notable.

It was also in the 1400,s that the great rebirth of learning called Renaissance was getting under way in Europe. Philosophers and scholars began questioning and investigating age-old beliefs. In astronomy, a starting break through came from an unlikely source-a derive and physician named Necolaus Copernicus.

Copernicus had a passion for astronomy. He was a keen observer himself and was familiar with other astronomers’ observations. He came to realize that Ptolemy’s concept of the universe was wrong. The odd movements of the planets could be explained simply if the sun, and not the earth was the centre of the universe. The planets circled around the sun and so did earth. Earth was merely another planet.

copernicus

Copernicus was not the first person to put forward the idea of solar system- a Universe centered on the sun. A Greek Philosopher named Aristarchus who lived in Samos had done so around 200 B.C. But no one listened to him.

The idea of a solar system took hold only slow and not before one ardent Copernicus, Giordano Bruno, was burned alive at the stake in 1600. In 1609 two events took place that consigned Ptolemy’s earth-centered view to history. Johannes Kepler in Germany calculated that planets travel around the sun, not in circle, but in elliptical (Oval) orbits which matched planetary observations exactly. Also in 1609 Gelileogalili in Italy turned a telescope on the heavens and saw sights no one had ever seen before. He saw mountains on the moon and moons circling around Jupiter. He also noticed that Venus showed phases something that could happen only if the planet circled around the sun.

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The expanding universe

As telescopes became more powerful, astronomers began to probe deeper into space. In 1781 William Herscher spotted a new planet, Uranus. It proved to be twice as far from Earth as Saturn, the most distant planet known to be ancients. At a stroke the size of the solar system had doubled. It expanded further when Neptune was discovered in 1846 and Pluto in 1930. There is a recent claim of discovery of a tenth planet.

By 1930 the true nature of the Universe had been put together. The solar system is a family of bodies centered on the sun. The sun is one of billions of stars belonging to a great galaxy called the Milky Way, a star island in space. There are many such star islands that group together in to ever greater group of clusters, to form the universe. But the universe is not a static arrangement of galaxies scattered through space. All the galaxies are rushing away from one another. The whole universe seam to be expanding as if from a primo dial explosion. Astronomers believe that such an explosion did take place about 15 billion years ago. The Big Bang is supposed to have created the universe and set it expanding. The only evidence for man-made model is the red shift and detection of cosmic Microwave Background. I will deal with these later. The truth is quite elusive.

 

 


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