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Sometime in late June or July 1609, Italian astronomer and physicist Galileo Galilei constructed his first spyglass—a simple contraption of lenses at the ends of a tube. The previous year in The Hague, a Dutchman named Hans Lipperhey had filed for a patent on the device, but it was Galileo who would go on to make it famous.
By the summer of 1609, Galileo, then a professor of mathematics in Padua, Italy, had managed to make a working model. His simple telescope would set off a revolution in the human understanding of the cosmos. He first used it to observe the moon and see the shadows cast by its mountains and craters; he went on to catalogue sunspots; and he discovered the four largest moons of Jupiter—Io, Europa, Ganymede and Callisto—that are now known as the Galilean moons in his honor.
Taken together, these observations would allow Galileo to support the Copernican view of the universe and not the Earth-centric view espoused by the church and by most educated men of the time. Galileo's discoveries would help supplant Ptolemaic astronomy, the vastly complicated and erroneous theory of celestial mechanics that had held sway for 1,400 years. (It has the dubious distinction of being among the longest-lived theories in science.)
In the centuries since Galileo first built his telescope, there have been huge improvements in the science, optics and technology behind the instrument. Today's state-of-the-art, Earth-based telescopes are mammoth structures, with flexible mirrors 10 meters across—devices that would have been completely unimaginable to Galileo and his immediate successors. Some of our clearest views of space have come from the orbiting Hubble Space Telescope, a technological wonder that continues to provide ever-improving glimpses into the universe nearly 20 years after its deployment. On the 400th anniversary of Galileo's spyglass, we take a look at some historic telescopes through the ages:
Slide Show: 10 Telescopes That Changed Our View of the Universe
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23 Comments
Add CommentThe Ptolemaic cosmology is a geocentric theory.
Reply | Report Abuse | Link to this"Earth-centric" is a pretty dumb way of saying geocentric.
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Reply | Report Abuse | Link to this"Both have adaptive optics that allow astronomers to cancel out some of the "fog" of Earth's atmosphere"
Reply | Report Abuse | Link to thisThat isn't accurate. No known technology can compensate for lack of transparency or fog. Adaptive optics compensate for turbulence or movement of the air. Movement of the air is called 'seeing' by astronomers. 'Good seeing' means the air is still. It is measured in arc seconds. Basically it measures how much a light beam gets swayed back and forth by the air it moves through.
"Both have adaptive optics that allow astronomers to cancel out some of the "fog" of Earth's atmosphere"
Reply | Report Abuse | Link to thisThat isn't accurate. No known technology can compensate for lack of transparency or fog. Adaptive optics compensate for turbulence or movement of the air. Movement of the air is called 'seeing' by astronomers. 'Good seeing' means the air is still. It is measured in arc seconds. Basically it measures how much a light beam gets swayed back and forth by the air it moves through.
Sorry if this got posted twice.
I recall reading (can't recall where) that simple telescopes were children's toys prior to Galileo...
Reply | Report Abuse | Link to thisI expected to see this one: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=16 mentioned here. FIRST is really a first, and will certainly fascinate us for years.
Reply | Report Abuse | Link to thisHow did Galileo observe sunspots with his telescope without destroying his eye(s)? Or to put the question differently, how did he know he had to use an indirect observation method and how did he set up his telescope to make the indirect observations?
Reply | Report Abuse | Link to thisgood stuff!!!
Reply | Report Abuse | Link to thisgreat stuff!!!!!!!
Reply | Report Abuse | Link to thisgreat stuff!
Reply | Report Abuse | Link to thisHow did Galileo observe sunspots with his telescope without destroying his eye(s)? Or to put the question differently, how did he know he had to use an indirect observation method and how did he set up his telescope to make the indirect observations?
Reply | Report Abuse | Link to thisAll Galileo had to do is create a sun filter by "sooting over" a piece of glass with a candle or oil lamp and place it in front of the scope.
Great, but why didn't Arecibo make the list?
Reply | Report Abuse | Link to thisHow did Galileo observe sunspots with his telescope without destroying his eye(s)? Or to put the question differently, how did he know he had to use an indirect observation method and how did he set up his telescope to make the indirect observations?
Reply | Report Abuse | Link to thisYour first attempt to directly observe the sun through a telescope would provide the knowledge that another method was needed. Indirect observation followed by observing the sun projected onto Galileo's hand and then onto a piece of paper of the time period. I wonder if the paper ignited trying this. Later focusing telescopes could easily project a larger image of the sun onto a light surface.
I think he would have realised how stupid it would be to look directly at the sun through a Telescope of any sort. What he probably did was to direct one end as normal towards the Sun and the other End towards a White wall in side a Room. I did the same witha pair of Binoculars a couple of years ago and saw the Moon travelling across the Face of the Sun.
Reply | Report Abuse | Link to thisbnjtokyo at 02:40 AM on 07/17/09
Reply | Report Abuse | Link to thisGalileo did a lot of damage to his eyes, I understand he was practically blind near the end of his life.
Being a pioneer has its risks.
Herschel's 40-ft telescope was quite unimportant, actually. He used a 6-ft Newtonian to discover Uranus, and a 20-ft reflector (actually several) to do much of his important work. The 40-ft telescope was a dud, and rarely used.
Reply | Report Abuse | Link to thisWho cares? It is quite sufficiently descriptive.
Reply | Report Abuse | Link to thisWho cares?
Reply | Report Abuse | Link to thisEarth-centric is a lot more descriptive than geo-centric anyway.
I think you should give credits to those before Galileo, including the Arabian scientists, who have strong influences on science in the Middle Ages. No need to be biased.
Reply | Report Abuse | Link to thisKnowledge comes from many part of the world, not only Britain, Europe and U.S.
Let the light comes from all part of the universe not only through our telescope, but also through our sincere heart.
I believe that there were some telescopes before Galileo that had influenced the Middle Ages scientists. The Arab scientists had their own telescopes and theories.
Reply | Report Abuse | Link to thisWe should not only let light from all part of the universe through our telescopes, but also through our sincere heart. At least, science should be neutral in its form.
You are nothing less than a superb, truly outstanding publication. Keep it coming.
Reply | Report Abuse | Link to thisEXCELLENT article ! You are nothing less than a superb, outstanding publication - the best of its kind. Keep it coming.
Reply | Report Abuse | Link to thisThank you , zony. The Arabs were making contributions not only to astronomy, but to all other aspects of science, mathematics, literature, and commerce LONG BEFORE Europe emerged from the darkness of the Middle Ages.
Reply | Report Abuse | Link to thisI am thoroughly disappointed in SA for making no mention of these advancements that influenced Galileo and the rest of the world forever.