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| Authored by: Anonymous on Thursday, July 05 2012 @ 04:21 PM EDT |
But there you're dealing with the interaction of two
separate axes - the axis of the ring's orbit around the
Earth, and the axis of the Earth's orbit around the sun, in
which case yes, twice per year the inclination of the rings
will be perpendicular to the sun and they would go "dark".
In this case though the axis of the rings *is* the sun, so
they are *always* "dark". Dark is a relative term though -
they have non-zero thickness so they're still absorbing some
sunlight, and re-radiating in the infrared, which is how we
can observe it. It's not inconceivable that the ring could
have "twisted" so tat we're now observing it edge-on, but
that would be a phenomenally difficult thing to accomplish.
The reason we have seasons, or that "Earth Rings" would go
dark occasionally, is precisely because their orientation
remains constant even while they move through space.
Changing the angle of the rings would be similar to changing
the Earth's orbit so it's no longer in the same plane as the
rest of the planets, only even more difficult because you're
talking about moving countless trillions of independent dust
particles instead of one big rock.
My own guess would be that either a wandering planet got
close enough to disrupt the rings as it' orbit
expanded/contracted (it wouldn't have to be a large one), or
there was a change in the sun's radiant or magnetic
properties that upset it's balance, though the latter would
likely have been apparent in the star's spectrum.
Hmm, it's also remotely possible that we just saw the birth
of a planet, with a single large enough clump of matter
having just coalesced into one spot that the rest of the
ring rapidly destabilized as everything was swept up by the
new planet. 2.5 Earth-orbit years = 10 Mercury-orbit years
(though they don't mention the star's mass, which would have
a big effect), so there might be enough time for a "sweep-
up" to take place if we assume that the orbit of individual
dust mores are fairly elliptical. Still, even if the
initial collapse were a very sudden event, I would expect
large clouds of material to remain at the L4 and L5 points
for some time. Hmm, I suppose that actually applies to a
wandering planet as well, so I guess I've got no compelling
ideas either.
Shoot, even dust-miners don't seem very compelling, you
wouldn't think they'd want *everything*, unless it was
actually antimatter or something. Then again I suppose a
fleet of world-ships or space-whales might find strip-mining
the occasional proto-system easier than mining rocky worlds
or gas giants, and with little risk of there being any
annoying natives to worry about.[ Reply to This | Parent | # ]
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