Mars orbiter lines up both Martian moons in one
photo: Scientific American Gallery -
http://www.scientificamerican.com/gallery_directory.cfm?photo_id=8E6C48CB-C925-05E5-86D78678378F19AA&sc=WR_20091217
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Astronomy.com - Theorists propose a new way to
shine and a new kind of star -
http://www.astronomy.com/asy/default.aspx?c=a&id=8895
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According to Butler, current indications are that
one-half of nearby stars have a detectable planet
with mass equal to or less than Neptune's.
Astronomy.com - New discoveries suggest low-mass
planets are common around nearby stars (18 December 2009)
http://www.astronomy.com/asy/default.aspx?c=a&id=8893
http://tinyurl.com/yfdqxxr
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More intriguing is what GJ 1214b might be.
Describing their discovery in the December 17th
Nature, a team led by David Charbonneau and
Zachary Berta (Harvard-Smithsonian Center for
Astrophysics) note that this world has about 6.5
times the mass of Earth (as told from the star's
gravitational wobble) but a full 2.7 times
Earth's diameter (as told by the transit depth).
Those specs don't match those of any other planet
in our solar system or known elsewhere. It has
almost the same mass as the one other transiting
"super-Earth" discovered so far, Corot-7b, but
the two could hardly be more different in makeup,
judging by their average densities. Whereas
Corot-7b is probably a molten-hot mix of rock and
metal, the average density of GJ 1214b (1.87
g/cm3 is too low for this world to be rocky and too high to be a gas giant.
Instead, it most likely consists almost entirely
of water, overlaid by a massive atmosphere. It's
thus the first specimen of an entire new class of
planet. (OK, OK, it's the second if you count the
wacky, hypothetical place portrayed in the 1995
sci-fi flick Waterworld.) Since it orbits so
closely, GJ 1214b probably has a surface
temperature near 400°F hot as an oven and
almost certainly devoid of life but still cooler
than any other known transiting planet. The
interior would be much hotter, but at the
extremely high pressures deep inside a planet,
even very hot water exists in solid form: hot ice.
SkyandTelescope.com - News Blog - A Weird,
Wonderful Waterworld? (18 December 2009)
http://www.skyandtelescope.com/community/skyblog/newsblog/79646632.html
http://tinyurl.com/y9ly8ph
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It has dawned on theorists in recent years that
other Earth-mass planets may be enormous water
droplets, balls of nitrogen or lumps of iron.
Name your favorite element or compound, and
someone has imagined a planet made of it. The
spectrum of possibilities depends largely on the
ratio of carbon to oxygen. After hydrogen and
helium, these are the most common elements in the
universe, and in an embryonic planetary system
they pair off to create carbon monoxide. The
element that is in slight excess ends up dominating the planet's chemistry.
In our solar system, oxygen dominates. Although
we tend to think of our planet as defined by
carbon, the basis of life, the element is
actually a fairly minor constituent. The
terrestrial planets are made of silicate
minerals, which are oxygen-rich. The outer solar
system abounds in another oxygen-rich compound, water.
Earth-Like Planets May Be Made of Carbon:
Scientific American (18 December 2009)
http://www.scientificamerican.com/article.cfm?id=a-large-lump-of-coal
http://tinyurl.com/ybmup5k
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