Here is a recent New Scientist article at:
http://www.newscientist.com/ns/19990619/news.html
which indicates there is a fine-tuning argument for design in the fact that
the Sun and moon have roughly the same apparent size in the sky and the
Earth, making perfect solar eclipses possible. The moon is the only one
among our solar systems 64 other moons which can make solar eclipses
visible from its planet.
Apparently for life to be viable, it needs a Sun our size, the distance
away it is, and an Earth and moon the size and distance apart they are:
"At the same time our existence depends on an unusually large moon since
its pull stops the Earth wobbling around too much on its axis and causing
wild and catastrophic swings in climate like those on Mars. Our Moon,
which is unusually large compared to those in almost all other planet-moon
systems, probably formed from molten material blasted from the Earth
during the impact of a giant body more than 4 billion years ago."
The article concludes:
"If Gonzalez is right, then all extraterrestrials, wherever they are, are likely
to live on planets like ours that experience total eclipses. But since an
unusually large Moon is rare, he says, this suggests that both ETs and total
eclipses are very rare indeed."
Steve
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[Archive: 19 June 1999]
It all fits...
Marcus Chown WHY DOES THE MOON look the same size as the Sun in
the sky? This coincidence, which makes the spectacle of total eclipses
possible, has been crying out for an explanation. Now an astronomer in
Seattle has proposed one. If he's right, there is a surprising connection
between the conditions required for a total eclipse and for the emergence of
intelligent life.
The coincidence in the apparent sizes of the Moon and the Sun occurs
because the Sun, though 400 times bigger than the Moon, is also 400 times
farther away. In fact, the Moon sometimes looks a shade bigger than the
Sun, which is essential for a "perfect eclipse" when the sky is dark enough
for you to see the Sun's faint outer atmosphere, or corona.
Because tidal effects cause the Moon to slowly recede from the Earth,
perfect eclipses have been visible only for about 150 million years and will
continue for only another 150 million years, about 5 per cent of the current
age of the Earth. Furthermore, Earth is the only planet in our Solar System
where a perfect eclipse is visible, although there are 64 other moons.
So are we just extraordinarily lucky? Guillermo Gonzalez of the University
of Washington in Seattle thinks not. He points out that our distance from
the Sun, and hence its apparent size, is a necessary condition for us to be
here. "If we were a little nearer or farther from the Sun, the Earth would be
too hot or too cold and so uninhabitable," says Gonzalez.
At the same time our existence depends on an unusually large moon since
its pull stops the Earth wobbling around too much on its axis and causing
wild and catastrophic swings in climate like those on Mars. Our Moon,
which is unusually large compared to those in almost all other planet-moon
systems, probably formed from molten material blasted from the Earth
during the impact of a giant body more than 4 billion years ago.
In the current issue of Astronomy & Geophysics (vol 40, p 3.18), Gonzalez
points out that the way the Moon formed means it started off very close to
the Earth and has taken several billion years to move far enough away until
it precisely covers the Sun during an eclipse. "The timescale is very similar
to that of the appearance of intelligent life," he says. "It is therefore not
such a big coincidence that we are around at the time when it is possible to
see total eclipses."
Gonzalez's explanation has generated much interest among astronomers,
though most remain cautious. "The timescale argument of Gonzalez needs
more checking," says John Barrow of the University of Sussex.
If Gonzalez is right, then all extraterrestrials, wherever they are, are likely
to live on planets like ours that experience total eclipses. But since an
unusually large Moon is rare, he says, this suggests that both ETs and total
eclipses are very rare indeed.
[...]
(c) Copyright New Scientist, RBI Limited 1999
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"All that is made seems planless to the darkened mind, because there are
more plans than it looked for. In these seas there are islands where the hairs
of the turf are so fine and so closely woven together that unless a man
looked long at them he would see neither hairs nor weaving at all, but only
the same and the flat. So with the Great Dance. Set your eyes on one
movement and it will lead you through all patterns and it will seem to you
the master movement. But the seeming will be true. Let no mouth open to
gainsay it. There seems no plan because it is all plan: there seems no centre
because it is all centre. Blessed be He!" (Lewis C.S., "Perelandra," The
Bodley Head: London, 1977, p251)
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