Author Topic: Question Re:- Transit of Venus  (Read 5219 times)

Offline gillianren

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Re: Question Re:- Transit of Venus
« Reply #15 on: November 04, 2015, 11:39:26 AM »
I mean, I do find it astounding that we're able to send probes to Pluto and have them get there, but to me, that's a tribute to the human ingenuity involved, not evidence that it didn't happen.  I guess that's because I never have been conspiratorially aware.
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Offline Cat Not Included

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Re: Question Re:- Transit of Venus
« Reply #16 on: November 04, 2015, 12:22:35 PM »
Then Donde got the idea that extra-solar navigation would be impossible because...well...it seemed to be he had no idea that a spacecraft could track its target and alter its course as necessary:

It doesn't help that more than one pop-sci tv show has stated that the accuracy required to send a space probe to a distant planet is equivalent to hitting a golf ball in Los Angeles and having it land on a Miami golf green. Since in-flight spacecraft course correction was not mentioned, some HB's took it as proof that the missions would be impossible to accomplish.

Definitely major problems with taking an analogy that's meant to give an idea of the distances involved as being therefore an analogy to everything else about the situation.

Please correct me if I'm wrong, but isn't the relative distance for a spacecraft actually easier to manage in some ways since space is mostly empty? You don't have to account for a complex, changing atmosphere with highly unpredictable wind conditions.
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Offline ka9q

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Re: Question Re:- Transit of Venus
« Reply #17 on: November 04, 2015, 03:32:12 PM »
Please correct me if I'm wrong, but isn't the relative distance for a spacecraft actually easier to manage in some ways since space is mostly empty? You don't have to account for a complex, changing atmosphere with highly unpredictable wind conditions.
Exactly. The physics of space travel is very "clean". None of that pesky friction, turbulence, wind or drag.

Offline smartcooky

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Re: Question Re:- Transit of Venus
« Reply #18 on: November 06, 2015, 10:06:14 PM »


Was it not a similar effect with the transit of Mercury that provided evidence for Einstein's General Theory of Relativity?

That was to do with perihelion shift, Newtonian physics predicts the shift of the perihelion by a certain amount. Basically relativity predicts a further shift due to gravity being a distortion in space time and Mercury's shift was in line with the predictions of relativity rather than Newton. OR something like that. :)

The best description I have seen was by Isaac Asimov in a short essay called "The Planet that Wasn't". This was basically the story of the non-existence of the intra-mercurial planet "Vulcan", a planet which was thought to have been the cause of the errors in Mercury's precession mesurements...

"By Einstein's relativistic view of the Universe, mass and energy are equivalent, with a small quantity of mass equal to a large quantity of energy in accordance with the equation e=mc2.

The Sun's enormous gravitational field represents a large quantity of energy and this is equivalent to a certain, much smaller, quantity of mass. Since all mass gives rise to a gravitational field, the Sun's gravitational field, when viewed as mass, must give rise to a much smaller gravitational field of its own.

It is this second-order pull, the small gravitational pull of the mass-equivalent of the large gravitational pull of the Sun, that represents the additional mass and the additional pull from within Mercury's orbit. Einstein's calculations showed that this effect just accounts for the motion of Mercury's perihelion, and accounted further for much smaller motions of the perihelia of planets farther out."


Full text of Asimov's essay here (it still a good read after all these years)

http://geobeck.tripod.com/frontier/planet.htm
 
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