Galileo's instrument was a simple affair, a refractor telescope that had two lenses at the ends of two tubes, one of which slid into the other. Using it, he first observed the moon in the fall of 1609, then the moons of Jupiter, and sunspots....[More]
GALILEO'S TELESCOPE:
Galileo's instrument was a simple affair, a refractor telescope that had two lenses at the ends of two tubes, one of which slid into the other. Using it, he first observed the moon in the fall of 1609, then the moons of Jupiter, and sunspots. He also resolved faint nebular patches into stars. By March 1610, he had published Sidereus Nuncius (Starry Messenger), the landmark treatise that documented his observations and his explanations for them. Galileo postulated that there are mountains and plains on the moon, noted that he could see 10 times as many stars through his telescope as with the naked eye, and he saw the moons of Jupiter and deduced that they orbit the planet.
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The Franklin Institute, Philadelphia
NEWTON'S TELESCOPE:
The British mathematician and physicist Isaac Newton built a telescope in 1670 that, unlike Galileo's device, used a mirror to gather and focus the incoming light....[More]
NEWTON'S TELESCOPE:
The British mathematician and physicist Isaac Newton built a telescope in 1670 that, unlike Galileo's device, used a mirror to gather and focus the incoming light. Such telescopes are called reflectors, and they offer major advantages over refractors, which use two lenses and suffer from optical distortion effects. Reflector telescopes can also be made much, much larger than refractors. All the giant telescopes today are reflectors, and Newton's design paved the way for their development.
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The Royal Society (UK)
HERSCHEL'S 40-FOOT TELESCOPE:
William Herschel, who discovered Uranus, built a reflecting telescope in Slough, England, that was 40 feet in length, the largest of its day. It was constructed from 1785 to 1789 at a cost of 4,000 pounds, which was paid by King George III....[More]
HERSCHEL'S 40-FOOT TELESCOPE:
William Herschel, who discovered Uranus, built a reflecting telescope in Slough, England, that was 40 feet in length, the largest of its day. It was constructed from 1785 to 1789 at a cost of 4,000 pounds, which was paid by King George III. It remained the largest telescope in the world for 50 years. On August 28, 1789, the first night of its operation, Herschel pointed it at Saturn and discovered one of its moons. He would go on to discover another of Saturnian satellite as well as two of Uranus's moons.
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Wikimedia Commons
MOUNT WILSON OBSERVATORY AND THE 100-INCH HOOKER TELESCOPE:
In the 19th and early 20th centuries, advances in glassmaking, along with lens grinding and polishing, led to the building of larger and larger telescopes, often on mountaintops that were suitable for astronomical observations because of thinner air and darker skies....[More]
MOUNT WILSON OBSERVATORY AND THE 100-INCH HOOKER TELESCOPE:
In the 19th and early 20th centuries, advances in glassmaking, along with lens grinding and polishing, led to the building of larger and larger telescopes, often on mountaintops that were suitable for astronomical observations because of thinner air and darker skies. In the U.S., observatories such as Lick in San Jose, Calif., and Yerkes in Williams Bay, Wisc., were among the first to show the uses of big observatories. American astronomer George Ellery Hale built a number of great telescopes, including the 100-inch Hooker telescope on Mount Wilson outside Los Angeles. The telescope, which started observations in 1917, was used by astronomer Edwin Hubble to gather data indicating an expanding universe, a discovery that shattered the steady-state cosmological orthodoxy of the time.
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Caltech
KARL JANSKY'S RADIO ANTENNA
Karl Jansky, a physicist who worked at AT&T Bell Laboratories in Holmdel, N.J., built a radio antenna that was roughly 100 feet long and 20 feet high to monitor short-wavelength radio waves....[More]
KARL JANSKY'S RADIO ANTENNA
Karl Jansky, a physicist who worked at AT&T Bell Laboratories in Holmdel, N.J., built a radio antenna that was roughly 100 feet long and 20 feet high to monitor short-wavelength radio waves. Jansky wanted to see if they interfered with transatlantic telephone calls. After months of observations, he noticed that one unidentified yet persistent source of noise was coming from the direction of the constellation Sagittarius. Jansky realized that the radio waves were coming from the center of the Milky Way. It was 1933, and this was the birth of radio astronomy.
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Bell Labs
PALOMAR OBSERVATORY AND THE 200-INCH HALE TELESCOPE:
The 200-inch Hale telescope on Mount Palomar, about three hours' drive south of Los Angeles, was also the brainchild of George Ellery Hale. The astronomer, however, did not live to see the completion of the scope, which took 20 years to build....[More]
PALOMAR OBSERVATORY AND THE 200-INCH HALE TELESCOPE:
The 200-inch Hale telescope on Mount Palomar, about three hours' drive south of Los Angeles, was also the brainchild of George Ellery Hale. The astronomer, however, did not live to see the completion of the scope, which took 20 years to build. Named in his honor, it saw its first light in 1949. Until the 10-meter Keck 1 was built in 1993, the Hale telescope had the best resolving power in the world. The telescope was central to solving the puzzle of quasars.
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Caltech/Palomar Observatory
HUBBLE SPACE TELESCOPE:
The first of NASA's Great Observatories, the Hubble Space Telescope was carried into orbit in 1990 by the space shuttle. Hubble was originally designed to observe in the visible and ultraviolet parts of the spectrum, but a 1997 mission added an infrared observing capability....[More]
HUBBLE SPACE TELESCOPE:
The first of NASA's Great Observatories, the Hubble Space Telescope was carried into orbit in 1990 by the space shuttle. Hubble was originally designed to observe in the visible and ultraviolet parts of the spectrum, but a 1997 mission added an infrared observing capability. Because it orbits hundreds of miles above Earth, Hubble does not suffer from the atmospheric distortions encountered by Earthbound observatories and has been our clearest eye into space, vastly expanding our knowledge of the cosmos and its origins.
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NASA
W. M. KECK OBSERVATORY
The twin giant Keck telescopes are situated at 4,150 meters atop Mauna Kea, one of the world's best astronomical observing sites, and each has a primary mirror that is 10 meters across....[More]
W. M. KECK OBSERVATORY
The twin giant Keck telescopes are situated at 4,150 meters atop Mauna Kea, one of the world's best astronomical observing sites, and each has a primary mirror that is 10 meters across. The first telescope, Keck 1, began observations in 1993, followed by Keck 2 in 1996. Taken together, they are the world's largest optical observatory. Both have adaptive optics that allow astronomers to cancel out some of the "fog" of Earth's atmosphere. Keck 1 has an infrared camera so sensitive, it is said that it could detect the flame of a single candle placed on the moon. The Keck Observatory has been invaluable in detecting extrasolar planets, worlds around other stars that were long postulated but only detected in the last dozen years or so.
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NASA/Keck Observatory
CHANDRA X-RAY OBSERVATORY:
Another of NASA's Great Observatories, Chandra was launched via the space shuttle in 1999. It primarily observes soft x-rays. The Earth's atmosphere absorbs most x-rays, so a space-based telescope is essential to gain good observations in that part of the spectrum....[More]
CHANDRA X-RAY OBSERVATORY:
Another of NASA's Great Observatories, Chandra was launched via the space shuttle in 1999. It primarily observes soft x-rays. The Earth's atmosphere absorbs most x-rays, so a space-based telescope is essential to gain good observations in that part of the spectrum. In its decade of existence Chandra has already produced many firsts, including the first observation of x-rays as matter streams into Sagittarius A*, the supermassive black hole at the center of the Milky Way Galaxy.
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Northrop Grumman Space Technology
SPITZER SPACE TELESCOPE:
The last of NASA's Great Observatories, Spitzer is a space-based infrared telescope. As it does with x-rays, Earth's atmosphere absorbs a lot of infrared radiation, so a telescope in space affords astronomers a much clearer view of the universe....[More]
SPITZER SPACE TELESCOPE:
The last of NASA's Great Observatories, Spitzer is a space-based infrared telescope. As it does with x-rays, Earth's atmosphere absorbs a lot of infrared radiation, so a telescope in space affords astronomers a much clearer view of the universe. Spitzer was launched in 2003 and has significantly advanced our knowledge of star-forming regions, young stars and other solar systems.
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NASA/JPL-Caltech
YES! Send me a free issue of Scientific American with no obligation to continue the subscription. If I like it, I will be billed for the one-year subscription.
"Both have adaptive optics that allow astronomers to cancel out some of the "fog" of Earth's atmosphere"
That 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"
That 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.
I 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.
How 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?
How 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?
All 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.
How 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?
Your 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.
14. peteringlis1
in reply to bnjtokyo02:25 PM 7/20/09
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.
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.
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. Knowledge 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.
We 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.
Thank 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.
I am thoroughly disappointed in SA for making no mention of these advancements that influenced Galileo and the rest of the world forever.
New Telescope Opens Its Eyes
Dome Big Dome: Giant Observatories Augur New Era of Cosmology
News Scan Briefs
Why Hi-Res Isn't Always Better
Origami Observatory: Behind the Scenes with the Webb Space Telescope
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.
.
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.