OBSERVATORY
The Kuiper Waltz
By HENRY FOUNTAIN
 he Kuiper Waltz
The early solar system can be likened to a crowd of dancers doing the
boogaloo in a nightclub — with lots of whirling, flailing and flinging
and even some pushing and shoving before things finally settled down.
There was also a lot of cutting in on partners, at least on the fringes
of the cosmic dance floor. New research suggests that pairs of
like-size bodies in the solar system's outer reaches were formed when a
third object broke up an existing pair.
The bodies are in the Kuiper Belt, that region beyond Neptune populated
with perhaps 100,000 relatively small objects (including, by most
classifications, Pluto, which is the largest of the lot). A small
percentage are binary pairs that orbit each other.
Elsewhere in the solar system, in most binaries — pairs of asteroids,
for example — one object is much larger than the other, the two are
close together and the orbit is circular. In the Kuiper Belt, however,
the bodies are of similar size and the orbits are wide and elliptical.
Writing in the journal Nature, scientists from Japan, Taiwan and the
United States have described a mechanism to explain the peculiarities
of these pairs.
The process, the scientists' simulations suggest, occurs in two stages.
The gravitational force of a relatively large body captures a smaller
one that passes close by, or even hits, the first. At a later point, a
third object, similar in size to the larger of the two, happens by.
The interloper cuts in, and all three dance together for a while. But
eventually the interacting gravitational forces kick the small body
out and the two remaining bodies waltz off together.
In the Mangrove Nursery
The world's mangrove forests are in trouble. By one estimate, more than
a third have been lost since the early 1980's because of coastal
development and other human activities. That is bad news for the
birds, lizards, turtles and other wildlife that make the wetland
forests their home.
But a mangrove forest is also a nursery, of sorts, for young fish that
as adults live around coral reefs. New research suggests that the
decline in mangroves could affect reef fish.
An international team of researchers led by British scientists studied
the makeup of fish communities in two types of reefs in Belize, those
with adjacent mangroves and those miles from the nearest forest. The
researchers visually surveyed 164 fish species, including many that
live in mangrove forests as juveniles.
According to their findings, which were reported in Nature, reefs with
neighboring forests produce much more abundant quantities of some
species, including commercially important varieties of snapper.
Reef fish have other potential nursery sites, including seagrass beds.
The researchers suggest that for certain fish, neighboring mangrove
wetlands may provide an intermediate habitat, one that offers
protection from predators. Those fish begin life in seagrass, migrate
to the mangroves and then to the reefs when they reach a certain age.
If there are no adjacent mangrove forests, they go straight from
seagrass to reef when they are still relatively small and easier
targets for reef predators.
Like Earth, but Not
A planet about 150 light-years from Earth has been found to have oxygen and carbon in its atmosphere.
The discovery was made by scientists using the Hubble Space Telescope.
It is the first time these two elements have been found in the
atmosphere of a planet outside the solar system.
The discovery does not mean that scientists have found life elsewhere.
Far from it, in fact. The planet, like most of the roughly 120
extrasolar planets found so far, is much closer to Jupiter in size than
Earth. It is also extremely close to its star. All that makes it an
inhospitable hot gas ball. The carbon and oxygen are naturally
occurring, not a result of some metabolic process. Get home delivery of The Times from $2.90/week
|
