Write your abstract here. PART I - Astronomers from NASA, Harvard and U of Colorado: "May be on Brink of Finding Habitable Second Earth".
"It could happen almost any time now. We now have the technological
capability to identify Earth-like
planets around the smallest stars." David Latham -Harvard-Smithsonian Center for AstrophysicsTo date, Planet hunters have spotted more than 200 planets beyond our solar
system, but the vast majority are hot, Jupiter-sized planets that would
dwarf the Earth and are almost certainly lifeless. Astronomers may be on the brink of discovering a second Earth-like
planet, a find that would add fresh impetus to the search for
extraterrestrial life, according to the US journal Science. Astronomers from six major
centers, including NASA, Harvard and the University of Colorado,
outline how advances in technology suggest scientists are on the verge
of being
able to detect the presence of small, rocky planets, much like
our own, around distant stars for the first time. The planets are
considered the most likely habitats for extraterrestrial life. One technique relies on observing the shift in light coming from a
star as a planet swings around it. Until recently, this "radial
velocity" method has only been sensitive enough to pick up planets far
more massive than Earth, but improvements now make the discovery of a
second Earth highly likely, said Dave Latham, a co-author on the paper
at the Harvard-Smithsonian Center for Astrophysics. "It could happen almost any time now. We have the technological
capability to identify Earth-like planets around the smallest stars
even now," he said.Earlier this year, the world''s largest and most prolific team of
planet hunters, the Anglo-Australian, California and Carnegie Planet
Searches ( AAPS), reported their findings of 37 exoplanets that have
been discovered over the past couple of years, 7 of which were
previously unreported brown dwarfs. Depending on whose number
you go by, the total number of exoplanets currently discovered is 212
or 240, the majority of which have been discovered by the AAPS and
their colleagues in the California and Carnegie searches. The
method of discovery primarily implemented is studying the Doppler
wobble of stars. As a
Planet orbits its parent star, its gravitational
pull causes the star to wobble. Using the Doppler Effect, the
scientists are able to determine the velocity of the planet. When the
planet moves away from Earth, its star moves toward the Earth, causing
it to emit shorter wavelengths, which appear bluer. The opposite is
true as well; as a planet moves closer to Earth, its star moves further
away, emitting longer (redder) wavelengths of light. The AAPS uses
highly advanced, sensitive spectographs to record these very small
wavelengths. But there are things that Doppler searches cannot
tell researchers. With Doppler readings, they are able to calculate the
velocities of the planets being studied as they move towards and away
from the Earth. What Doppler readings are unable tell researchers are
the angles of inclination of the orbital planet to the line of sight.
This is important information because by being able to calculate the
angles of inclination of the orbiting planet, scientists are able to
determine the actual physical size of the planet. The AAPS has
developed a technique to find the angle of inclination: transit
searches. Transit searches are a relatively new technique which has
only just begun giving them results within the past few years. As a
planet transits in front of its parent star, passing our line of sight
from Earth, scientists are able to calculate its angle of inclination,
thereby determining its eccentricity (how elliptical or round its
orbital path is). In the years to come, the method of transit searches
should advance, resulting in more informatioabout already discovered
planets. Although the next generation of techniques such as
interferometric astrometry and direct imaging will be the most
promising new methods of detection in the future study and discovery of
extrasolar planets, as Chris Tinney of AAPS explains, the most
successful and powerful form of study currently in use is complementing
Doppler searches with transit searches. By doing so, “You can
essentially know everything you can know about a planet. You know
exactly its mass and its radius, which means you can work out its
density,” and therefore, “you can make estimates as to whether it’s a
gas giant or an ice giant planet, or whether it’s rocky.” Because of limited space, please read continuation in PART II - Astronomers from NASA, Harvard and U of Colorado: "May be on the Brink of Finding Habitable Second Earth".
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