Links to additional science reports are given below.
Detecting alien worlds presents a significant challenge since they are
small, faint, and close to their stars. The two most prolific techniques
for finding exoplanets are radial velocity (looking for wobbling stars)
and transits (looking for dimming stars). A team at Tel Aviv University
and the Harvard-Smithsonian Center for Astrophysics (CfA) has just
discovered an exoplanet using a new method that relies on Einstein's
special theory of relativity.
One breakthrough to come in recent years is direct imaging of
exoplanets. Ground-based telescopes have begun taking infrared pictures
of the planets posing near their stars in family portraits. But to
astronomers, a picture is worth even more than a thousand words if its
light can be broken apart into a rainbow of different wavelengths.
"This appears to be the best example our team has found yet of
Earth-like planets in the habitable zone of a sun-like star," said team
astrophysicist Alan Boss of the Carnegie Institution for Science
of Washington. Kepler-62 is close by astronomical standards at about
1,200 light years away (708,000 trillion miles). It's a star slightly
smaller than our sun, so its "habitable zone" for planets is closer in.
The two ocean-friendly planets have "years" of 122 days and 267 days —
the time it takes to completely orbit the star — for that reason.
"We now estimate that if we were to look at 10 of the nearest small
stars we would find about four potentially habitable planets, give or
take," said Ravi Kopparapu, a post-doctoral researcher in geosciences.
"That is a conservative estimate," he added. "There could be more."
"In the 19th century it was thought impossible to know the composition
of stars, but the invention of astronomical spectroscopy has revealed
detailed information about nearby stars and distant galaxies," said
Charles Beichman, executive director of the NASA Exoplanet Science
Institute at the California Institute of Technology. "Now, with Project
1640, we are beginning to turn this tool to the investigation of
neighboring exoplanets to learn about the composition, temperature, and
other characteristics of their atmospheres."
NASA's Kepler mission scientists have discovered a new planetary system
that is home to the smallest planet yet found around a star similar to
our sun.
In the last two decades astronomers have found hundreds of planets in
orbit around other stars. One type of these so-called 'exoplanets' is
the super-Earths that are thought to have a high proportion of rock but
at the same time are significantly bigger than our own world. Now a new
study led by Helmut Lammer of the Space Research Institute (IWF) of the
Austrian Academy of Sciences suggests that these planets are actually
surrounded by extended hydrogen-rich envelopes and that they are
unlikely to ever become Earth-like. Rather than being super-Earths,
these worlds are more like mini-Neptunes.
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As of September 2008 the count of known exoplanets is over 300.
As of September 2011, over 700 exoplanets have been discovered.
Searching for extra-solar planets -- which are planets outside of our solar system -- is very popular these days. About 700 planets are known at the moment, a number that is continuously rising due to refined observational techniques.
As of October 2012, over 800 confirmed sightings of exoplanets have been made. Over 2000 unconfirmed sightings have been made.
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