Four hundred years ago, Galileo and his telescope brought the heavens into focus, setting the stage for modern astronomy
Such a small thing, really--two pieces of glass and a tube no longer than the span of a man's arm. The first telescope that Galileo built (and I don't mean he was the first to build one, for surely he wasn't) played tricks with distance and size. The device transported faraway objects into the viewer's presence, and magnified them there. As Galileo demonstrated to the Doge of Venice in 1609, even an entity invisible to the naked eye, such as an enemy ship on the horizon, would loom large within the purview of his spyglass.
Later, alone in the dark, after he'd learned how to grind better lenses, Galileo pointed his instruments skyward to reveal uncomfortable truths about the universe:
1. The supposedly smooth, silvery orb of the moon mimicked the Earth with chains of mountains and depths of valleys.
2. The familiar constellations contained more stars than anyone had counted, while the mysterious Milky Way consisted of nothing but stars, too densely packed for unaided eyes to discern.
3. The planet Jupiter commanded a retinue of four attendant bodies--"never seen since the beginning of time," as Galileo pointed out--whose positions changed from hour to hour.
4. Venus, when followed through the telescope, waxed and waned like the moon.
5. And the large pair of companions on either side of Saturn occasionally disappeared!
This year, four centuries after those early nights of wonder, the International Year of Astronomy salutes Galileo for ushering in a new worldview. 2009 also commemorates the 400th anniversary of the publication of Astronomia Nova, by Johannes Kepler, who propounded laws of planetary motion as stunning as Galileo's observations.
The International Astronomy Union and the United Nations Educational, Scientific and Cultural Organization (UNESCO) have designated this year as the International Year of Astronomy 2009 in tribute to the 400th anniversary of the astronomical discoveries of Galileo and Johannes Kepler, who's A New Astronomy, was published in the same year as Galileo’s discoveries with the telescope.
Galileo is primarily recognized for his use of the telescope to demolish the centuries-old Aristotelian-Ptolemaic (earth-centered) view of the universe and the resultant clash with the Catholic Church. His 1609 accomplishments include significant improvements to the telescope, detailed sketches of the Moon’s features, followed by, in 1610, the discovery of the four moons of Jupiter (now known as the Galilean moons) and the odd shape of Saturn (the telescope was still too primitive to discern the rings), his observations of sunspots, and the discovery that Venus went through phases similar to those of the Moon.
The 400th anniversary of Galileo’s insight of using what was originally called a spyglass and subsequently renamed the telescope to observe and understand the heavens has occasioned some comment in the media; most of it is of a celebratory and superficial nature, with little, if any, that provides an understanding of what Galileo’s accomplishments represent historically and scientifically.
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