Thirty-three light-years away, in the
constellation Leo the lion,
astronomers say they have found a world
considerably smaller than
Earth, orbiting a dim red-dwarf star. That's
something to think about.
While scientists have confirmed the
existence of more than 700 so-called
exoplanets since 1995, most of them have been
giant -- many considerably
larger than Jupiter. This new world,
say the researchers who found it, may
be only 5,200 miles across, about two
thirds as large as Earth. "People have been
picking at the low-
hanging fruit, since Jupiter-sized
planets are easier to see," said Kevin
Stevenson, the young researcher at
the University of Central Florida who
led the team making the find. "Now we're
really pushing the limits of what
our telescopes can find." The newly found
world is, for now,
called UCF-1.01, and Stevenson and
his colleagues found it with NASA's
Spitzer space telescope in Earth orbit.
It orbits a star called GJ 436. They
spent a year watching it to confirm that it was
indeed a distant world.
They are publishing their find online
Thursday in the Astrophysical
Journal. UCF-1.01 is probably not a very nice
place. Stevenson and his group
calculated that it whips around its
host star in only 1.4 Earth-days, at a
distance of about 1.6 million miles
(we're 93 million miles from our sun).
Temperatures on its surface probably
exceed 1,000 degrees Fahrenheit,
raising the possibility that some of it is
molten, covered in lava. Any
atmosphere would have boiled away
long ago, said the researchers. They could not
see it directly -- its sun
is nothing but a dot in a telescope --
but they could see a tiny dip in the
star's brightness as the disc of
UCF-1.01 passed in front of it. For
now, they cannot even calculate its mass;
current technology is not good
enough for a reliable number. Nobody will be
launching a mission to
UCF-1.01 anytime soon; there are
other worlds, including moons of
Jupiter and Saturn, that look much
more promising as homes for living
things. Still, the find suggests that if this world
could be detected, others --
perhaps in the so-called habitable
zones around their host stars -- may
soon be found as well. "The discovery was
completely by
accident," said Stevenson in a
telephone interview with ABC News.
They were looking at another, much
larger planet orbiting the same star,
"and there were these spurious signals we
could not explain