Galileo's telescope at 400: From Spyglasses to Hubble: Facts, Myths, More

National Geographic News ^ | August 25, 2009 | Victoria Jaggard

[SunkenCiv]

Just over 400 years ago, Galileo--then chair of mathematics at Italy's University of Padua--got word that Dutch glass makers had invented a device that allowed viewers to see very distant objects as if they were nearby.

The mathematician soon acquired a Dutch instrument, and on August 25, 1609, he presented an improved, more powerful telescope of his own design to the senate of the city-state of Venice. The government officials were so impressed with Galileo's telescope that they rewarded the professor with a higher salary and tenure for life at his university.

At the time, Galileo was touting the telescope for commercial and military applications, such as watching ships at sea. But in the fall of 1609 Galileo turned his telescope to the heavens, setting into motion a new kind of science: telescopic astronomy.

[SunkenCiv]

Galileo's telescope at 400

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[SunkenCiv]

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[yarddog]

The optical quality must have been amazing for the time. I have two 20 and 30 power high end spotting scopes, both have ED glass and I have difficulty making out the moons of Jupiter or the rings or Saturn yet Galileo could see them with an uncoated lens.

[SunkenCiv]

He had cleaner skies, and probably somewhat cooler weather, plus he probably viewed when the planets' positions were optimum. :')

• Galileo-Kepler Correspondence, 1597

World's oldest telescope?
by Dr David Whitehouse
Thursday, July 1, 1999

According to Professor Giovanni Pettinato of the University of Rome, a rock crystal lens, currently on show in the British museum, could rewrite the history of science. He believes that it could explain why the ancient Assyrians knew so much about astronomy. It is a theory many scientists might be prepared to accept, but the idea that the rock crystal was part of a telescope is something else. To get from a lens to a telescope, they say, is an enormous leap. Professor Pettinato counters by asking for an explanation of how the ancient Assyrians regarded the planet Saturn as a god surrounded by a ring of serpents?

[the_Watchman]

Back in the 1970’s there was a Scientific American article talking about either an asteroid or a comet. The people who were tracking a modern sighting of this astronomical artifact were trying to extrapolate back in time and concluded that it might have been visible to Galileo during his months of logging the moons of Jupiter.

The rest of the article speculated on Galileo’s equipment and techniques. He had successfully calculated the periodicity of several of Jupiter’s moons using what was probably an 8 power telescope [I could be way off, but 8 is what I remember.] He also plotted the trajectories of the moons as they transited across the surface of the planet.

They presume that he held graph paper up to see with one eye while he sighted Jupiter with his other eye. He moved the paper until the images were superimposed and then counted grids. He apparently did not document his approach, so this was speculation on their part.

Low and behold, in one corner of his charts Galileo noted a bright object moving in the correct direction from night to night which could very well have been the sought after comet or asteroid! Thus the investigators got a data point from nearly 400 years ago.

Like a previous poster pointed out, Galileo had the advantage of a clean atmosphere and nearly no city lights! :)

[NormsRevenge]

I marvel at those who did so much discovery with so little in the way of instruments. Cool stuff!

[dr_lew]

The mathematician soon acquired a Dutch instrument, and on August 25, 1609, he presented an improved, more powerful telescope of his own design to the senate of the city-state of Venice.

In THE ASSAYER Galileo makes the explicit claim that he constructed his telescope within days of hearing a description of its use only, and not its design, and without having examined or having seen any other telescope.

[NRPM]

Until Sep. 7 you can see one of Galileo’s telescopes at the Franklin Institute in Philadelphia:

http://www2.fi.edu/exhibits/traveling/galileo/

[plsvn]

the rings or Saturn yet Galileo could see them with an uncoated lens.

Actually Galileo didn't make out the rings of Saturn as rings. He though the planet Saturn had two moons, one on either side.

[dr_lew]

Until Sep. 7 you can see one of Galileo’s telescopes at the Franklin Institute in Philadelphia:

I saw it last week while visiting back East. The telescope itself isn't much to look at, so you have to use your imagination. They have one hall right after this filled with various scientific demos, including optical replicas of Galileo's 'scopes.

These were built like tanks! You could hit them with hammers without messing up the alignments, I think. I guess they have learned the hard way. They are pointed at images mounted at the end of the hall simulating the views of Jupiter and Saturn, kind of like an eye test at the optometrist. All in all, very well done.

[tlb]

Galileo can make all the claims he wants about the Moon, Jupiter, and Saturn, but you know darn well he was spending a lot of those nights at the telescope checking out the bedroom window of Maria Gambrelli.

[SunkenCiv]

;’)

[SunkenCiv]

Thanks NRPM! I was going to go there to locate some codes in the Silence Doogood letters, but...

[SunkenCiv]

Thanks dr_lew.

[SunkenCiv]

Ditto!