Editing Fermi paradox (section)

=== Direct planetary observation ===
[[File:Earthlights dmsp 1994–1995.jpg|thumb|upright=1.35|A composite picture of Earth at night, created using data from the [[Defense Meteorological Satellite Program]] (DMSP) Operational Linescan System (OLS). Large-scale artificial lighting produced by human civilization is detectable from space.]]
Exoplanet detection and classification is a very active sub-discipline in astronomy; the first candidate [[terrestrial planet]] discovered within a star's [[habitable zone]] was found in 2007.<ref>{{Cite journal |doi=10.1051/0004-6361:20077612 |arxiv=0704.3841 |title=The HARPS search for southern extra-solar planets XI. Super-Earths (5 and 8&nbsp;{{Earth mass}}) in a 3-planet system |journal=Astronomy & Astrophysics |volume=469 |issue=3 |pages=L43–L47 |last1=Udry |first1=Stéphane |last2=Bonfils |first2=Xavier |last3=Delfosse |first3=Xavier |last4=Forveille |first4=Thierry |last5=Mayor |first5=Michel |last6=Perrier |first6=Christian |last7=Bouchy |first7=François |last8=Lovis |first8=Christophe |last9=Pepe |first9=Francesco |last10=Queloz |first10=Didier |last11=Bertaux |first11=Jean-Loup |year=2007 |bibcode=2007A&A...469L..43U |s2cid=119144195 |url=http://exoplanet.eu/papers/udry_terre_HARPS-1.pdf |url-status=dead |archive-url=https://web.archive.org/web/20101008120426/http://exoplanet.eu/papers/udry_terre_HARPS-1.pdf |archive-date=October 8, 2010 }}</ref> New [[Methods of detecting extrasolar planets#Other possible methods|refinements in exoplanet detection methods]], and use of existing methods from space (such as the [[Kepler space telescope|Kepler]] and [[Transiting Exoplanet Survey Satellite|TESS]] missions) are starting to detect and characterize Earth-size planets, to determine whether they are within the habitable zones of their stars. Such observational refinements may allow for a better estimation of how common these potentially habitable worlds are.<ref>From {{cite web |url=http://kepler.nasa.gov/Mission/QuickGuide/ |title=Kepler: About the Mission |publisher=NASA |date=March 31, 2015 |access-date=March 30, 2016 |archive-url=https://web.archive.org/web/20120420015542/http://kepler.nasa.gov/Mission/QuickGuide/ |archive-date=April 20, 2012 |url-status=dead }} "The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey a portion of our region of the Milky Way galaxy to discover dozens of Earth-size planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets."</ref>