The first five years of this ten have been , without a doubt , a turn peak in exoplanetary discoveries . Before the launch of the Kepler Space Observatory , only a handful of planets outside our Solar System were known . Now the telephone number of confirmed major planet isclose to 2,000 , with thousands more candidates waiting for confirmation from subsequent observation .
The latter part of this decade will focus on the good understanding of the planets we have found so far . The goal is simple : to determine habitable planets . With this objective in mind , astronomers from theUniversity of Washington ’s Virtual Planetary Laboratoryhave created a habitability index to rate exoplanets so that follow - up explorationsin the next few age can prioritize the most promising candidates . Their oeuvre has been accepted for publication in theAstrophysical Journal .
The " habitability index for transiting planet " is constructed only with usable experimental information . As long as the planet ’s orbital time period , the duration of passage across its host star , star surface gravity , radius and temperature are all know , it is possible to forecast the power – which quantifies the likelihood that a transit planet may possess fluent water on its surface . The indicator also depends on several factors such as the rockiness of the planet , its peck and albedo . The albedo quantifies the amount of starlight think over back into space by the planet .
Traditionally , scientistsdetermine whether an exoplanet is possibly habitable by consider whether it sits in its host star topology ’s inhabitable zone , otherwise known as its " Goldilocks zone . " This is when the region around a star is not too spicy or too cold and has the right condition for liquid water to form on the planet ’s surface . So , once the space of a satellite from its sensation is calculated , the planet is either in or out of the habitable geographical zone . This is logically correct ; a satellite is either inhabitable or inhabitable , but this entropy can only tell us so much .
" That was a enceinte first stair , " study writer Rory Barnes read in astatement , " but it does n’t make any distinctionswithinthe inhabitable zone . " On the other hired hand , the habitableness index is a uninterrupted variable rather than a yes or no category , produce more subtle distinctions and including some important factors that make a major planet truly inhabitable .
While the habitableness index finger is an authoritative new cock , it has limitations . Some of these are theoretical ( the complex properties of rocky planets , eccentric orbit complications ) , while others are due to the constraints on the datum . More oeuvre is necessary , but with theTransiting Exoplanet Survey Satellitescheduled to set in motion in 2017 and Hubble ’s replacement , theJames Webb Space Telescope , scheduled for 2018 , it is important to possess a statistical tool that allows us to quantify where to best taper our instrument .
Top image quotation : James Webb Space Telescope Artist Conception by Northrop Grumman , viaFlickr . CC BY - NC - ND 2.0
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