Orbital Mechanics

Dr Robert Matthews, in the Sunday Telegraph, 2003-11-22, p.35, reports
an assertion given by Prof Carl Murray (U of London) regarding the Moon
that implies that the angular velocity of a secondary about the empty
focus of its elliptical orbit is constant. That could be true; but if so
I would expect it to be well-known. I do not recall it.

Comment, anyone? Mike D??



Thinking about the eclipse measurements - here's an exercise for the
group, possibly also suited to the students of the establishments of MD
and/or ST, or to their colleagues.


Given a standard length of one Toise (which is a bit over a fathom), and
using NO other measurement standards, and using NO given numbers in SI,
etc., units : determine as much as possible about the size of the Earth
/ Moon / Sun / Solar System, in MegaToises and GigaToises.

Standard physics and maths can be assumed known, and the Solar System
understood. Existing SI data can be used to assess feasibilities.

All the sorts of equipment normally available to such people may be
used; any scales can be assumed to be linear but otherwise *not*
*calibrated*.

A trap; the scale of a sextant cannot be presumed to be in
degrees, but that of a normal protractor can, since the line
joining 0 to 180 goes through the centre.

Students can do it as a gedankenexperiment; they can describe how to
work up from their Toise to a measure of the distance from, say, Yes Tor
to Snowdon, or Wareham to Tweedmouth, without actually doing it (those
pairs are on lines of longitude, near enough).

Uncertainties should be estimated. Eclipses, etc., assumed available on
demand.

Note that we do have access to the Radio Pips, against which a watch can
be tested; and observations of the angular altitude and direction of ISS
at an agreed instant provide data not available to the ancients. Etc.
For shorter distances, measure aircraft.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm; quotes.htm; pascal.htm; &c, &c.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.