The Amateur Astronomy Club of C-DAC (A2C2) has been actively involved in popularising the science of astronomy amongst the members of C-DAC and their families.

Ashish Kuvelkar, an active member of A2C2 briefly dwells on the fascinating objects in sky in the article.

Astronomy, defined as a study of celestial objects, is the oldest of all the sciences. Early civilizations in China dating back to 2450 BC recorded phenomena like comets and eclipses, where as Indian sky watchers made astronomical observations for agricultural and religious purposes.

In the last century BC, the Greeks distinguished between stars, which seemed stationary relative to each other and planets, which shifted slowly from one constellation of stars to another. They believed in the theory of central earth and Ptolemy, one of the well-known astronomers of those times, supported it.

Copernicus challenged the Plotemaic theory in 1543AD. He replaced the Earth from its proud central position by the Sun. Anticipating a violent reaction from the church, he was wise enough to defer publication of his book until the end of his life. His fears were well founded and his theory was condemned.

Observational astronomy got support from science in 1609 when Johannes Kepler published ‘Astronomia Nova’ in which he defined the first two laws of planetary motion. The change in outlook (from Earth centred to Sun centred system) was complete when Isaac Newton published ‘Principia’ in 1687. This book has been described as the "greatest mental effort ever made by one man". The foundation for the modern phase of astronomy was thus laid.

Astronomy gives us an opportunity to appreciate and explore something much bigger than ourselves - the universe. Looking at the night sky can be a transcendent, and humbling experience. But most of all, it's fun, family oriented and offered free by nature. Individuals, parents and children can participate with a minimum of equipment like a pair of binoculars or an amateur telescope.

The sky is divided into 88 areas, known as constellations. They serve as a convenient way of locating positions of the objects in the sky. Although the stars of a constellation appear in the same direction in the sky, they are actually at differing distances from us and usually have no physical connection between each another.

Constellations come in varying sizes and shapes. The smallest is Crux, the southern cross. The largest one Hydra, the water snake is a long figure that covers an area of sky 19 times bigger than Crux. The constellations were named after gods, heroes and fabled animals by ancient people. With a few exceptions, the connections between star patterns and respective people or animals are symbolic rather than literal. These include the 12 constellations of the zodiac, through which the sun passes on its yearly journey.

There are several systems for labeling stars. Usually, the stars in a constellation are named by Greek letters, in order of their brightness. Like the brightest star in Centaurus is called a Centaruri, the second brightest b Centaruri and so on. Many of the brighter stars have proper names like Antares, Betelgeuse and Sirius.

Not all stars are white as they appear in first look. The Colour of stars vary from deep-orange through yellow to blue white. The color of the star depends on its surface temperature. Coolest stars are red while hottest are blue.

Unlike stars, planets of our solar system shine by reflecting light from the Sun. Since they keep traveling in orbit around the Sun, their location with respect to other objects is not fixed. Nowadays many newspapers publish sky maps in the beginning of the month which are helpful in locating constellations and planets. Sky maps are also available on some of the popular astronomy websites.

Mercury and Venus orbit between Sun and Earth and hence are seen close to horizon. Mercury is a hard to see object since it never strays far from the Sun. It can be seen only for sometime before sunrise or after sunset. Venus is the brightest planet and outshines all the stars. When seen through amateur telescope, it is seen as a disk that goes through phases like that of the moon.

The Moon is the most spectacular object when seen through the telescope or a binocular. Since the Moon's axial rotation period is exactly equal to its orbital revolution period(27.32 days), we get to see only it's near side. The appearance of the Moon's surface changes dramatically form one night to next because of changing angle between Earth, Moon and Sun. Craters, which are close to illumination boundary, look imposing.

Mars is notable due to its red color, but could be a disappointing sight through an amateur telescope due to its small size. Jupiter is the second brightest planet. When seen through a small telescope, four bigger moons (Io, Europa, Ganymede & Callisto) out of 16 moons can be seen changing their position around Jupiter from night to night.

Saturn presents another beautiful telescopic sights, being encircled by rings. Out of 18 moons of Saturn only one, Titan is visible through small telescope. The other planets Uranus, Neptune and Pluto are too distant and too faint to be visible.

Most people have a passing interest in astronomy. If one takes it as a serious hobby, it can very well be a very satisfying and enriching experience.

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