Comments on: Ep. 171: Solar System Movements and Positions

By: Andreas Yankopolus

Andreas Yankopolus — Sun, 21 Feb 2010 18:36:10 +0000

Is there a good reference that discusses how an earthbound observer goes about determining planetary orbits. I’ve been scratching my head on how Kepler turned Brahe’s tables of observations into the planetary orbits from which he derived his laws. In particular, how did he correct for the motion of the Earth, as the planets would shift against the starry background due to parallax? Then there’s the issue of some planets lying inside Earth’s orbit while others lie outside. And it’s not like he had Newton’s law of gravity or even calculus to aid him, so he must have made some clever insights that I’m missing.

By: John G

John G — Sun, 14 Feb 2010 16:16:18 +0000

Yes, the Copernicus conflation with Ptolemy bothered me too. I guess on a logarithmic scale of astronomical achievement and discovery, you could say there was virtually nothing important which happened between their work; that is, on an historical timeline they abut each other. After all, what is a mere 1400 years in the overall lifetime of the universe? (all of this is tongue-in-cheek).
Given the lapses of time between episodes, Frasier and Pamela were probably recording several shows back-to-back.

By: llewelly

llewelly — Fri, 12 Feb 2010 13:18:09 +0000

Pamela has some things mixed up. Ptolemy and Copernicus were not “at about the same time”.

Frasier (3:28): Right. And then along came Copernicus.
Pamela (3:31): Well and along came Ptolemy at about the same time … (3:50) The sun is governed by Apollo, Copernicus worshiped Apollo, it worked. … (4:09) And sadly, at about the same time, we had Ptolemy …

Ptolemy (the one that wrote Almagest) lived from about 90 CE to about 168 CE. Copernicus lived from 1473 CE to 1543 CE. Not “at about the same time”. Initially I had thought maybe Pamela meant to say Aristarchus, but he lived much earlier, 310 BCE to 230 BCE.

I submitted this comment (but with a few supporting links) a day or so ago, but it failed to appear. What gives?

By: Evan

Evan — Fri, 12 Feb 2010 05:22:22 +0000

might i suggest a second part to this episode, i was expecting some info on the suns orbit around the super massive black whole.

and then perhaps how long it will take to find out if the super massive black holes and our galaxys are orbiting something even in the supposed rapid expansion of the universe.

By: Michael

Michael — Fri, 12 Feb 2010 01:02:59 +0000

Ptolemy was a contemporary of Copernicus?
Copernicus the Catholic cleric worshipped Apollo??
Copernican theory had no epicycles???

I’ve always enjoyed the accuracy of Astronomy Cast but in the first 3 minutes there were 3 things said that are completely the opposite of historical fact — and they are quite important for the show’s topic too! First time I stopped listening from disappointment — what happened?