NASA DISCOVERS “MOST EARTHLIKE PLANET YET”

Posted: December 6, 2011 in by John Dilligent
Tags: , , , ,

NASA has announced the discovery of the “best bet yet” for extraterrestrial lifeforms 

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On December 5, 2011, NASA announced that the latest reseach concerning the discovery two years ago of a planet outside our solar system has revealed what they are now calling “the latest, best potential target for life.”

They have named the planet Kepler 22-b. It is about 600 light-years from Earth and about 2.4 times its size, lies in the so-called “Goldilocks Zone”, has a relatively comfortable surface temperature of about 22C (72F), and orbits a star not unlike the Earth’s sun. But while astronomers believe that it “probably” also possesses water and land, experts are not yet sure if it is made mostly of rock, gas or liquid.

The discovery was made by NASA’s Kepler planet-hunting telescope. The telescope, launched by NASA, is watching 155,000 stars and looking for tiny drops in brightness that betray the presence of planets. This is called the “transit system” of planet-finding.

The star around which Kepler-22b orbits, in the region of the constellations of Lyra and Cygnus, is slightly smaller than the Sun and about 25% dimmer. The planet orbits the star in 290 days, at a distance 15% closer than the Earth is from the Sun. It lies right in the center of the star’s habitable zone, where potentially perfect conditions exist for life.

It is the first time that Kepler has confirmed a planet outside Earth’s solar system in the not-too-hot, not-too-cold “Goldilocks” habitable zone. This is the band where temperatures are just right to allow the existence of surface liquid water throughout a planet’s orbit.

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This handout illustration made available on December 5, 2011 by NASA, a diagram compares our own solar system to Kepler-22, a star system containing the first ‘habitable zone’ planet discovered by NASA’s Kepler mission. (NASA/AFP/Getty Images)

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This image from NASA’s Kepler mission shows the telescope’s full field of view — an expansive star-rich patch of sky in the constellations Cygnus and Lyra stretching across 100 square degrees, or the equivalent of two side-by-side dips of the Big Dipper. (NASA / Courtesy)

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The Kepler spacecraft shown at Ball Aerospace preparing to be shipped to Florida. Photo Credit: NASA/JPL/Ball Aerospace & Technologies Corp. (NASA / Courtesy)

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On Launch Pad 17-B at Cape Canaveral Air Force Station in Florida, United Launch Alliance’s Delta II rocket carrying NASA’s Kepler spacecraft rises through the exhaust cloud created by the firing of the rocket’s engines. Liftoff was on time at 10:49 p.m. EST on March 6, 2009. (NASA / Courtesy)

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The spectacular nighttime launch of a Delta II rocket carrying the Kepler planet-hunting spacecraft lifted off on time at 10:49 p.m. EST from Launch Complex 17-B at Cape Canaveral Air Force Station in Florida. (NASA / Courtesy)

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Artist’s representation of HD 209458 b, an extrasolar planet (unofficially referred to as Osiris), that orbits the Solar analog star HD 209458 in the constellation Pegasus, some 150 light-years from Earth’s solar system, with evidence of water vapor. Found by the Kepler telescope. (NASA / Courtesy)

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The Three Steps For Identifying Habitable Worlds

Recognizing habitable worlds around other stars is a challenging process. Extrasolar planets, also known as exoplanets, are very far away and most of them are only known by their effect on their parent star. They make their stars wobble in space (radial velocity oscillations) or periodically block their light (transits). Only a few have been directly imaged, those large and hot enough. Even with these observational limitations scientists are starting to identify potential habitable candidates within the over 2,000 exoplanets that have been detected so far.

A habitable world is one that seems capable of supporting life as we know it, but not necessarily implies that it is habited. The process of identifying habitable worlds can be divided in three steps. The completion of these steps is necessary to confirm that these worlds are in fact habitable for any terrestrial life or even habited by unknown life forms. Unfortunately, scientists are only able now to complete the first step and in some very special cases the second. Future ground and orbital observatories are necessary to go through all steps and therefore confirm their habitability.

Step 1: Physical Indicators: Basic Stellar and Planetary Properties

Habitable world are first recognized by their orbital position with respect to their parent star and some basic planetary properties such as mass and radius. Only exoplanets with the right size and inside the stellar habitable zone, or the right distance from their star to support liquid water, are considered potentially habitable. Small exoplanets will not be able to hold an atmosphere and much larger ones will have very high surface pressures that will even make any water solid, independently of temperature.

Step 2: Chemical Indicators: Atmospheric Chemistry

Habitable worlds are also recognized by the composition of their atmosphere. A planet that has the right temperatures for liquid water does not necessarily mean that it has water. The light from the atmosphere of the planet is analyzed in search for the presence of water and other gases required by life such as oxygen, carbon dioxide, methane, and nitrogen. The presence of these gases is not a guarantee for the existence of life but only strong indicators of habitability.

Step3: Biological Indicators: Biosignatures

Habitable worlds are finally confirmed by the observation of strong indicators for the presence of life. Life that is abundant and globally distributed will have and impact on the chemistry of the atmosphere and how light is absorbed at their surface. For example, any vegetation will absorb light in some particular energies that can be recognized. The presence and abundance of oxygen and methane, two usually relatively short-lived gases in planetary atmospheres, are also good indicators of biological process that are replenishing them.

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Special thanks to NASA , located at: http://www.nasa.gov/

And

The Planetary Habitability Laboratory, located at: http://phl.upr.edu/

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