After this observation, the haze closed in again and no observation was possible for a while. When the sky cleared again, the sunspot had moved. Moved much further in an hour or so than a sunspot ordinarily moved in a day, but just about as much as the planet Mercury would have moved.
To understand what Gassendi was expecting to see, we must cast our minds back some 1500-odd years before Gassendi, to about the year 150 AD. At that time, the astronomer we know as Claudius Ptolemy published a book which came to be known by the name Almagest, from an Arabic expression meaning the greatest, although Ptolemy himself modestly called it simply a Mathematical Treatise. By whatever name, the book was a set of mathematical procedures for predicting the future location of planets in the sky based on observations of their past locations. This was a difficult task, since the motion of the planets is strangely irregular, or so it must have seemed to the ancient Greek astronomers.
Showing posts with label science with an exclamation point. Show all posts
Showing posts with label science with an exclamation point. Show all posts
Saturday, September 21, 2013
Friday, September 20, 2013
One post in every calendar year, that's my motto.
And so far it hasn't steered me wrong, as Theophile Escargot said in a different context.
Paris. November 7, 1631. Pierre Gassendi has been watching the sun for two days, now, hoping to see something that no one in the history of the world has ever before seen: the passage of the planet Mercury across the face of the sun, a transit of Mercury.
Not that this has never happened before. In fact, it happens about 13 times every century, at irregular intervals. But no one before Gassendi has had both the tools and foreknowledge to observe the transit.
The foreknowledge is courtesy of the recently deceased German astronomer Johannes Kepler, who four years earlier in 1627 had published his Rudolphine Tables, the most accurate astronomical tables computed up to that time (all calculations done by hand, of course) and a year before, in 1630, had published an "Admonition" pointing out to Europe's astronomers that a transit of Mercury was predicted for November 7th, and advising that they watch for it, cautiously suggesting that they watch from November 6th to the 8th in case of errors in his observations or computations. Gassendi, even more cautious, decided to start watching on the 5th.
Paris. November 7, 1631. Pierre Gassendi has been watching the sun for two days, now, hoping to see something that no one in the history of the world has ever before seen: the passage of the planet Mercury across the face of the sun, a transit of Mercury.
Not that this has never happened before. In fact, it happens about 13 times every century, at irregular intervals. But no one before Gassendi has had both the tools and foreknowledge to observe the transit.
The foreknowledge is courtesy of the recently deceased German astronomer Johannes Kepler, who four years earlier in 1627 had published his Rudolphine Tables, the most accurate astronomical tables computed up to that time (all calculations done by hand, of course) and a year before, in 1630, had published an "Admonition" pointing out to Europe's astronomers that a transit of Mercury was predicted for November 7th, and advising that they watch for it, cautiously suggesting that they watch from November 6th to the 8th in case of errors in his observations or computations. Gassendi, even more cautious, decided to start watching on the 5th.
Saturday, April 17, 2010
Prompt
This comment says:
in 1990, Robert Alan Haag, one of the biggest traders* of meteorites of the world, tried to steal the second largest meteorite of the world from Chaco, Argentina. He mounted a huge operation to lift and move this 37 ton piece and take it to the U.S.
*:The original word here was "trades", which I assume was a typo. -de
in 1990, Robert Alan Haag, one of the biggest traders* of meteorites of the world, tried to steal the second largest meteorite of the world from Chaco, Argentina. He mounted a huge operation to lift and move this 37 ton piece and take it to the U.S.
*:The original word here was "trades", which I assume was a typo. -de
Monday, February 8, 2010
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