Naturalist Iapetus

Strangers in strange lands

After a while you get the feeling the solar system is a pretty strange place.
Not only from looking at otherworldly pictures of moons and planets sent
from spacecraft, but also because scientists say so.
At least a half-dozen objects, probably more, have been described as "the
strangest place in the solar system" by some awestruck authority. I imagine
Jupiter's moon Io might get the most overall hits on the word "strangest." It
warps, buckles, seethes and erupts like no other known place. Uranus' moon
Miranda might run second - it's small and round but it's weirdly jagged, with
sheer cliffs miles deep.
There's also Saturn's moon Titan, which is covered in a heavy orange smog
(and, apparently, lakes) of hydrocarbons that might nourish life. And
Neptune's moon Triton, which is probably the coldest place of all (minus 390
degrees Fahrenheit, colder than Pluto, or hell) but nonetheless has a thin
nitrogen-methane atmosphere, spews ice, and revolves around Neptune
backwards. Also strange is Jupiter's moon Europa, which is covered by a
frozen ocean.
Some of Saturn's other moons get called strange too. Hyperion, which looks
almost exactly like a russet potato, is the largest irregularly shaped object in
the solar system. Enceladus is nearly pure white, the brightest non-sun object
known, and shoots out water ice.
Then there's Iapetus. It's less than half the size of our moon. (Nothing
strange there - most moons are smaller than ours.) But last year the Cassini
spacecraft sent close-up photos of its surface that looked even stranger than
it did through telescopes in the 1960s, when it already seemed so uncanny
that Arthur C. Clarke portrayed it as a stargate to other dimensions in the
novel "2001: A Space Odyssey." Iapetus is half dark and half light - literally.
In its orbit around Saturn, which takes about 79 Earth days, its leading half is
practically black, and its trailing half is very bright, practically white.
Now, some astronomers say this is the strangest thing in the solar system.
No other object is neatly divided half and half of anything. What's weirder
still is that almost exactly along the middle of Iapetus, where the dark divides
from the light, is a mountain range, in places eight miles high. It resembles
the ridge around a walnut shell. No other known moon has a mountain range
exactly tracing its equator.
The bright half of Iapetus is covered by ice. The photos show what looks
like snow fields over small and huge craters. The dark half, which seems
black but is generally a very dark reddish color, is thought to be made of
organic materials. No one knows how it got like this. Black splatters on the
dividing line lead to the theory that material from another Saturnian moon,
possibly Hyperion or Phoebe, somehow inundated Iapetus' leading half and
coated it black.
I don't know if this is as strange as Io's horrible, belching sulfur volcanoes
and seething yellow surface. But no one can say, really. "Strange" is not a
scientific word (except for one specialized use in subatomic physics, where it
does not mean strange at all), even though astronomers use it all the time.
"Strange" means different or unfamiliar in a way that causes uneasiness and
allure. "Strange" is a feeling you get, not an objective physical condition.
When you think about it, the place most different from everything else in the
solar system is not Io or Iapetus, but the Earth, with its blue oceans and
greenery and living beings. To us, it's familiar. In other places, we're the
strangers, with strange words to describe what in our hearts feels very
strange. It's a strange universe.

© Dana Wilde 2008
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