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3

Well, you CAN do it, but it's not the best way to do those types of measurements on land. The advantage of a sextant on a boat is that you can account for the rocking of the boat by rhythmically rocking your body back and forth. If you take a sextant, add a bubble level, attach it to a tripod, and remove the mirrors used to line up with the horizon, what ...


10

To understand the answer provided below, we need to reframe the original question slightly. Perhaps a better way to put "was libration first predicted" is to say, outright, libration was first observed, then a theory was advanced explaining its occurrence. Although the observation of libration is documented in 1632 by Galileo, and independently ...


6

According to Wood Galileo was the first to observe libration in longitude and latitude and make notes of it, described in his Siderus Nuncius. Given that exact observations, and comparisons require detailed photos or images, it seems unlikely that this libration was observed earlier. An interesting read on the discussion among the leading scientists around ...


18

The variable speed of the Moon on the celestial sphere has been known since ancient times. The Babylonians made ~7 centuries of daily astronomical observations from around 700 BC. That data was the basis of the astronomical tables of Hipparchus, which Ptolemy used in creating the formulae of celestial motions in the Almagest. However, actually observing the ...


5

Your actions are laudable. Actually, these bubble jobbers have been around for a long time. You are probably using a pattern sextant and desire to affix a bubble horizon to it. Yes, you can do this. Nevertheless, there are bubble sextants for the same use; the principal advantage, of course, being that readings can be taken when the sky is visible but the ...


10

...pulsing bright rainbow of colors... Sounds like very bad astronomical seeing effects. Even a steady atmosphere acts like a weak prism and in fact all dielectrics tend to bend blue light more than red. When are wedge prisms used to correct chromatic effects of atmospheric refraction? (atmospheric dispersion) Astronomical seeing is basically disordered ...


6

The city sky is not black. It is so bright it "washes out" the stars. You discern objects because of contrast between them and their background. Think of a polar bear against the snow. All you see is the eyes and the nose because the bear doesn't contrast with the background. If you looked at a polar bear in the forest, no such problem, The city ...


2

I went to in-the-sky.org/skymap.php changed the location to Chennai and set the clock back two an evening days. I found Venus in the west, clicked on it so see it's RA and Dec Found Wikipedia's page for the constellation Ophiuchus, found the map, and put a red dot where Venus was. It seems like M19 and M62 were to the East of Venus and M9 was north of it. ...


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