Tagged Questions
1
vote
1answer
112 views
What are “cycles of anomaly” and “cycles of longitude”?
In several early (pre-1600) astronomical texts I read about "cycles of anomaly" and "cycles of longitude", but it us unclear to me what these terms mean. They were clearly familiar to authors at the ...
1
vote
0answers
116 views
What is the angular distance between Ptolemaic perigees of Mercury?
In his excellent treatment of the history of the science of astronomical distances and sizes, Albert van Helden says (p.29) that
The complicated [Ptolemaic] model of Mercury has the curious ...
3
votes
1answer
232 views
When and how were relative distances to the planets first measured?
I understand that the absolute distance to a planet can be measured using earth-baseline (e.g., diurnal) parallax, and that the first reasonably accurate such measurement was made for Mars by Cassini ...
8
votes
2answers
268 views
Was Jupiter's mass “guessed at” by Kepler or Galileo?
Following Kepler's publication of his 3rd law of planetary motion1,
$$p^2 / r^3 = 1$$
in 1619, it would have been possible to use telescopic observations to arrive at an estimate of the orbital ...
