In the Shadow of the Moon

Except that in that book the Earth sized body is a moon of the Jupiter
sized planet, not a Trojan.


And the 4th moon of Yarvin, in _Star Wars_.

But having an Earth form and orbit a Jupiter may not ever happen.
There's some analysis of Jupiter, Saturn and Uranus and computer
simulations that were done to show that the max total mass of a
Jupiter's moon system is about 1/10000 of the planet's mass. Neptune's
system seems to be too oddball to use for this, as Triton may be half of
a captured Kuiper belt binary object. The other object running off with
the extra orbital energy to let Trition settle in orbit around Neptune.
Anyway, you may need a really big Jupiter, like 30 times our Jupiter's
mass, to get enough mass limit to have an Earth. But our Earth may be
bigger than it needed to be, to have life happen.

or ~ 1/10 the apparent size of the Sun or Moon.

( ( ) )

So the disk would be large enough to be quite noticeable. Wow! That
really underscores just how immense Jupiter really is!

One can only imagine what the ancients would have done with that!


And it would be in a permanent gibbous phase! At a phase angle of 60
degrees (assuming it or the earth planet doesn't wander much)

Which happened first, the mathematical analysis that the L points exist,
or discovery of trojan asteroids at the L points of Jupiter? Finding
trojans after the math was done is a nice way to confirm scientific
mathematics work. Making up math to fit something already observed
isn't quite as good.

In article et,
robert casey wrote:
Which happened first, the mathematical analysis that the L points exist,
or discovery of trojan asteroids at the L points of Jupiter?

The mathematics came first -- Lagrange's analysis of the three-body
problem, and discovery of the five quasi-stable points, was published in
1772, and the first two Trojans were found (quite by accident, by people
surveying for main-belt asteroids) in 1906.

Finding trojans after the math was done is a nice way to confirm scientific
mathematics work...

Actually, the people who found the first one (Achilles) were astonished;
the more mathematically-minded astronomers all knew of Lagrange's work,
but nobody had thought it had any practical relevance...

(A more striking case came later: people studying the effects of mascons
on lunar orbits discovered that Lagrange had studied a simple mathematical
model for it... prefacing his analysis with the comment that it could have
absolutely no application in the solar system...!)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In sci.space.history message
hlink.net, Thu, 21 Jun 2007 20:31:23, robert casey
posted:

Which happened first, the mathematical analysis that the L points
exist, or discovery of trojan asteroids at the L points of Jupiter?
Finding trojans after the math was done is a nice way to confirm
scientific mathematics work. Making up math to fit something already
observed isn't quite as good.

See http://en.wikipedia.org/wiki/Lagrangian_points,
http://en.wikipedia.org/wiki/Trojan_asteroids.
Prediction, 1772, Lagrange.
Observation, 1904, Barnard; with recognition, 1906, Wolf.

--
(c) John Stockton, Surrey, UK. Turnpike v6.05 MIME.
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

(Henry Spencer) wrote:

(A more striking case came later: people studying the effects of mascons
on lunar orbits discovered that Lagrange had studied a simple mathematical
model for it... prefacing his analysis with the comment that it could have
absolutely no application in the solar system...!)

Which reminds me to rerun an old question: is there any citation for
geosynchronous/geostationary orbits, or their counterparts for other
bodies, before Tsiolkovsky in 1895? They're mathematically trivial
special cases, but -- without a natural example -- did anyone even
remark the possibility before T. started thinking about putting things
in space?

On Jun 22, 5:16 am, Monte Davis wrote:
(Henry Spencer) wrote:
(A more striking case came later: people studying the effects of mascons
on lunar orbits discovered that Lagrange had studied a simple mathematical
model for it... prefacing his analysis with the comment that it could have
absolutely no application in the solar system...!)

Which reminds me to rerun an old question: is there any citation for
geosynchronous/geostationary orbits, or their counterparts for other
bodies, before Tsiolkovsky in 1895? They're mathematically trivial
special cases, but -- without a natural example -- did anyone even
remark the possibility before T. started thinking about putting things
in space?

Sorry, as even our moon's L1 is still fully taboo/nondisclosure rated,
and that's enforced by those pesky Zion MIB (aka Atheists) to boot.
Earth's L1 is nearly as off-limits and/or need-to-know rated. Earth's
L4 and L5 as well as those of our moon are simply to weird and cosmic
hot to touch for accommodating much of anything except inert/robotic
applications. Even our moon's L1 is too freaking DNA/RNA nasty as all
get out, unless artificially surrounded by sufficient mass.
-
"whoever controls the past, controls the future" / George Orwell
-
Brad Guth

In article ,
Monte Davis wrote:
Which reminds me to rerun an old question: is there any citation for
geosynchronous/geostationary orbits, or their counterparts for other
bodies, before Tsiolkovsky in 1895? They're mathematically trivial
special cases, but -- without a natural example -- did anyone even
remark the possibility...

Not that I'm aware of. There are some natural examples of bodies with
satellites both above and below the stationary orbit, and thinking about
the tidal evolution of such orbits could call some attention to that orbit
as a dividing line in behavior (above it, tidal effects move the orbit
outward; below, inward), but I don't know if anyone specifically noted
that orbit's unusual properties.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |