- Five new satellites - and one candidate moon - have been
discovered orbiting the giant planet Neptune, bringing its tally of moons
to 13.
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- Two orbit in the same direction as the planet rotates,
while the orbits of the others are opposite to Neptune's spin.
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- The tiny outer satellites are probably captured asteroids,
astronomers say.
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- Cataclysmic events connected to the capture of Neptune's
moon Triton were thought to have destroyed any outer satellites the planet
once had.
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- The new moons, named S/2002 N1 to N4 and S/2003 N1, are
in eccentric, tilted orbits. They are all between 30km and 50km in diameter.
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- An international team of astronomers searched for the
satellites between 2001 and 2003 using the 4m Cerro Tololo Inter-American
Observatory and the 3.6m Canada-France-Hawaii telescope.
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- Elusive sixth
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- The researchers used a technique to look for the new
moons that was originally developed to detect very faint objects in the
outer Kuiper Belt.
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- They also observed a sixth candidate moon, which they
have named c02N4. This was discovered on 14 August 2002 and seen again
at the Very Large Telescope (VLT) on 3 September 2002. But further attempts
to spot this object failed.
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- The researchers say this could be Centaur - an object
that has migrated from the outer Kuiper Belt. But its lack of movement
relative to Neptune is more consistent with it being a satellite.
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- The satellites are unlikely to have condensed from material
around Neptune.
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- Instead, these so-called irregular moons may be the product
of a parent body that collided with Neptune's moon Nereid and were then
disturbed in their orbits by the capture of Triton from the Kuiper Belt.
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- © BBC MMIV http://news.bbc.co.uk/2/hi/science/nature/3578210.stm
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