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Slightly OFF TOPIC - I've been trying to find references to any articles/stories about how early astronomers first estimated the distance from the Earth to the

by rman666 15y ago

Slightly OFF TOPIC - I've been trying to find references to any articles/stories about how early astronomers first estimated the distance from the Earth to the Sun (using only observational astronomy). It appears the distance was first estimated in multiples of the distance from the Earth to the Moon. If you happen to know of any quality articles about how these estimates were made (and how a modern amateur astronomer might duplicate them), I'd appreciate a link. Thus far, Google searches have only been mildly useful.

jackfoxy 15y ago
Not exactly what you're looking for, but Newton explained the irregularities of the moon's orbit in the third book of his Principia. Unhappily I struggled through Cajori's revision of Mott's translation before a modern English translation became available in 1999.
sehugg 15y ago
It hinges on observations made during the transit of Venus across the Sun: http://en.wikipedia.org/wiki/Transit_of_Venus http://en.wikipedia.org/wiki/Transit_of_Venus Eli Maor wrote a great book "Venus in Transit" that accounts this multi-century quest to accurately measure this event, which occurs very rarely and requires accurate timekeeping across large distances to compute the triangulation. It's a fascinating story.
- rman666 15y ago
  Thank you for the link.
- sehugg 15y ago
  BTW, the next transit is in June 2012, and it's likely the last opportunity any of us living today will get to see it: http://www.transitofvenus.org/june2012/where-to-be http://www.transitofvenus.org/june2012/where-to-be
ColinWright 15y ago
I don't have time to find more relevant things for you now, but some of the techniques appear in this paper: http://www.solipsys.co.uk/HowHighTheMoon.pdf http://www.solipsys.co.uk/HowHighTheMoon.pdf In addition to that, early measurements were made by trying to compute the angle of the Sun to the horizon when the Moon was exactly at quarter. The angles involved are very small (or very close to 90 degrees) making the results very sensitive to errors. The wikipedia article gives a good overview of the ideas: http://en.wikipedia.org/wiki/Astronomical_unit#History http://en.wikipedia.org/wiki/Astronomical_unit#History This article also covers the basics: http://galileoandeinstein.physics.virginia.edu/lectures/gkastr1.html http://galileoandeinstein.physics.virginia.edu/lectures/gkas... But you probably knew all that.
- rman666 15y ago
  I knew some, but not all of that. Thanks for the links!

by rman666 15y ago

jackfoxy 15y ago

Not exactly what you're looking for, but Newton explained the irregularities of the moon's orbit in the third book of his Principia. Unhappily I struggled through Cajori's revision of Mott's translation before a modern English translation became available in 1999.

sehugg 15y ago

It hinges on observations made during the transit of Venus across the Sun: http://en.wikipedia.org/wiki/Transit_of_Venus http://en.wikipedia.org/wiki/Transit_of_Venus Eli Maor wrote a great book "Venus in Transit" that accounts this multi-century quest to accurately measure this event, which occurs very rarely and requires accurate timekeeping across large distances to compute the triangulation. It's a fascinating story.

rman666 15y ago
Thank you for the link.
sehugg 15y ago
BTW, the next transit is in June 2012, and it's likely the last opportunity any of us living today will get to see it: http://www.transitofvenus.org/june2012/where-to-be http://www.transitofvenus.org/june2012/where-to-be

ColinWright 15y ago

I don't have time to find more relevant things for you now, but some of the techniques appear in this paper: http://www.solipsys.co.uk/HowHighTheMoon.pdf http://www.solipsys.co.uk/HowHighTheMoon.pdf In addition to that, early measurements were made by trying to compute the angle of the Sun to the horizon when the Moon was exactly at quarter. The angles involved are very small (or very close to 90 degrees) making the results very sensitive to errors. The wikipedia article gives a good overview of the ideas: http://en.wikipedia.org/wiki/Astronomical_unit#History http://en.wikipedia.org/wiki/Astronomical_unit#History This article also covers the basics: http://galileoandeinstein.physics.virginia.edu/lectures/gkastr1.html http://galileoandeinstein.physics.virginia.edu/lectures/gkas... But you probably knew all that.

rman666 15y ago
I knew some, but not all of that. Thanks for the links!