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Telescope - the ultimate discovery

tech reviews Updated: Jan 07, 2010 18:23 IST
Satyen Mohapatra

Four hundred years ago today (January 7, 1610) Galileo Galilie made a profound discovery which changed Man's view of the universe for all times to come.

Using a home made telescope with 15-20 times magnification this Italian astronomer looked to the skies and discovered the moons of Jupiter circling round that planet.

Galileo wrote in Sidereus Nuncius , " . . On the 7th day of January in the present year, 1610, in the first hour of the following night, when I was viewing the constellations of the heavens through a telescope, the planet Jupiter presented itself to my view, and as I had prepared for myself a very excellent instrument, I noticed a circumstance which I had never been able to notice before, namely that three little stars, small but very bright, were near the planet……"

He believed them to fixed stars, but they made him "somewhat wander" as they were "arranged exactly in a straight line" , and were "brighter than the rest of the stars, equal to them in magnitude".

On January 8th, "led by some fatality", he turned again to look at the same part of the heavens and found a very different state of things, for there were three little stars all west of Jupiter, and nearer together than on the previous night.

"I therefore concluded, and decided unhesitatingly, that there are three stars in the heavens moving about Jupiter, as Venus and Mercury around the Sun." Later his observations showed not only three, but four, "……. bodies performing their revolutions around Jupiter."

Jupiter's four largest satellites Io, Europa, Callisto and Ganymede are now known as Galilean satellites.

Galileo's discovery was a major blow to the geocentric model of Greek philosopher Ptolemy which held sway for centuries that earth is at the centre of the universe and the sun and all the other heavenly bodies move round it.

Galileo's find also substantiated 15th century Polish astronomer Nicolaus Copernicus's heliocentric model that sun is the centre around which the earth and other planets move which gradually replaced the Ptolemaic view of the universe.

The Roman Catholic Church for committing heresy by advocating Copernican views condemned Galileo, as the Church believed that earth is stationary. He spent the last years of his life under house arrest. He died a blind man on Jan.8, 1642.

In 1992 Pope John Paul said Church's denunciation of Galileo's work had been a tragic error and in December 2008 Pope Benedict XVI also paid tributes to Galileo stating, "An understanding of the laws of nature could stimulate appreciation of God's work."

National Co-ordinator of Astronomica Vikrant Narang told HT, "Galileo is credited to be the first man to point a telescope towards the skies.His discovery marks the birth of modern astronomy. Today the wonderful sights seen by Galileo can be seen by anyone with even a modest telescope or bionocular.

"Astronomy has progressed tremendously in the last 400 years. Today we are in the era of Space telescopes and have discovered millions of galaxies and several solar systems orbiting other stars" he added.