Hubble pic of Crab Nebula
August 17, 2009 -- Almost 400 years after Galileo turned his telescope to the stars -- and heralded the birth of modern astronomy -- this image of the Crab Nebula was recorded by the Hubble Wide Field and Planetary Camera 2 (WFPC2). The Jet Propulsion Laboratory’s WFPC2, which operated aboard Hubble from 1993 until it was returned to Earth in 2009, made over 135,000 observations of the universe.
Four hundred years ago this October, the Italian polymath Galileo Galilei made a telescope and began a series of celestial observations that ended with the heretical discovery that everything in the heavens did not revolve around us.
Proclaimed the “father” of many things, including astronomy, science and modern physics, Galileo was not -- despite being frequently credited as such -- the father of the telescope, so much as its adoptive parent. He was, however, the man who in 1609 used it to change the way we look at the universe and our place in it.
Such records as survive show that several men before Galileo had a reasonable claim to having invented the instrument. In September 1608, for instance, Dutch officials considered -- and rejected -- an application for a patent from Hans Lipperhey, a spectacle-maker for a “device by means of which all things at a very great distance can be seen as if they were nearby”.
Others were almost certainly already making and selling similar instruments -- after all, the raw materials had been on hand for more than a hundred years. Spectacles for correcting vision had been in use from the late 14th century, at first utilising crudely ground convex lenses to produce reading glasses for the elderly and, later, concave lenses to correct short-sightedness.
The name of the craftsman who first lined up and peered through a combination of the two, and thus “invented” the telescope, is lost to history; the true origin of the telescope, says The Galileo Project, “is inaccessible to us since craftsmen were by and large illiterate and therefore historically often invisible”.
But whoever invented it, the telescope was “the first extension of one of man’s senses, and … helped shift authority in the observation of nature from men to instruments. In short, it was the prototype of modern scientific instruments.”
The earliest known drawing of a telescope, by the Italian scientist Giovanpattista della Porta, dates from August 1609; according to his own writings, Galileo first heard about the instrument in May 1609.
The crude models in circulation, limited by the simple lenses then available for spectacles, could magnify by up to only three times and were little more than a novelty. Galileo, however, saw the potential. Teaching himself to grind and polish the improved, stronger lenses he needed, by the end of August 1609 he had produced an instrument capable of nine-times magnification.
Others soon caught up with Galileo -- his lead was in the application, rather than the theory -- but the significant breakthrough was to belong to him.
At first, his sights were set not on the heavens, but on war. The telescope, he wrote in a letter to the Senate of Venice that year, “is a thing of inestimable benefit for all transactions and undertakings, maritime or terrestrial, allowing us at sea to discover at a much greater distance than usual the hulls and sails of the enemy, so that for two hours and more we can detect him before he detects us”.
By November 1609, however, he had made a telescope with times-20 magnification, and this he pointed skywards, first at the Moon and then at Jupiter. When he did, everything changed.
In a series of observations throughout January 1610, culminating in a decisive sighting on the 15th of the month, he discovered that Jupiter had four moons. Invisible to the naked eye, they were the first objects seen to be orbiting any heavenly body other than the Earth and the Sun. Since then, a total of 63 moons have been discovered around Jupiter.
Galileo was not slow to celebrate his discovery, which he recorded in a book published just two months later, in March 1610. Politically astute -- and dependent on their generosity -- in “Sidereus Nuncius” (The Starry Messenger), he named the moons after the four brothers of his patron family, the Medicis.
The names didn’t stick, however. Those adopted by posterity were chosen by a German astronomer, Simon Marius; Io, Europa, Ganymede and Callisto, the four lovers of Zeus, the god of the sky and thunder and the Greek equivalent to the Roman Jupiter. Marius claimed to have discovered them a few days before Galileo but was slower off the mark when it came to getting out his book. “The Jovian World, discovered in 1609 by means of the Dutch Telescope”, wasn’t published until 1614.
Galileo, however, has had the last laugh.
This year has been named International Year of Astronomy, in honour of Galileo’s achievements 400 years ago. As part of the international programme, the organisers have developed a cheap but high-quality telescope, designed to bring stargazing to a generation of young people in parts of the world where such a device, like the stars, would normally be beyond reach. The name of the instrument? The Galileoscope, of course.