Changes

'''Gliese 581 d''' was discovered alongside and announced at the same time as [[Gliese 581c|Gliese 581 c]], also sitting within the [[habitable zone]] of Gliese 581, and is now the prime candidate for habitability among the known worlds of the Gliese 581 system.  It is the fourth of the four known worlds in distance from its parent star.

'''Gliese 581 d''' was discovered alongside and announced at the same time as [[Gliese 581c|Gliese 581 c]], also sitting within the [[habitable zone]] of Gliese 581, and is now the prime candidate for habitability among the known worlds of the Gliese 581 system.  It is the fourth of the four known worlds in distance from its parent star.

The planet has a mass of at least 7.09 (maximum of 13.8) times that of Earth.  Glises 581 d has a mean orbit of 0.22 AU, which it completes in 66.8 days.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>  In April of 2009, after further studies, the planet was confirmed to be within the habitable zone where liquid water could exist with a greenhouse effect under the right atmospheric conditions.<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref>  The planet is thought to be too massive to be made only of rock and may have been an ice world at one time, with the abundant ices melting into deep worldwide [[ocean|oceans]] as the planet migrated closer to Gliese 581.<ref>http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html</ref>

The planet has a mass between 7.09 and 13.8 times that of Earth.  Gliese 581 d has a mean orbit of 0.22 AU, which it completes in 66.8 days.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>  In April of 2009, after further studies, the planet was confirmed to be within the habitable zone where liquid water could exist with a greenhouse effect under the right atmospheric conditions.<ref name="habit">http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf</ref>  The planet is thought to be too massive to be made only of rock and may have been an ice world at one time, with the abundant ices melting into deep worldwide [[ocean|oceans]] as the planet migrated closer to Gliese 581.<ref>http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html</ref>

=== Gliese 581 e===

=== Gliese 581 e===

The discovery of '''Gliese 581 e''' was announced on April 21, 2009. The planet is estimated to have a minimum mass only 1.9 times that of Earth making it the smallest [[extrasolar planet]] in the system and the smallest extrasolar planet known overall.  It is the closest of the four known worlds in distance from its parent star.

The discovery of '''Gliese 581 e''' was announced on April 21, 2009. The planet is estimated to have a minimum mass only 1.9 times that of Earth making it the smallest [[extrasolar planet]] in the system and the smallest extrasolar planet known overall.  Of the four known worlds it is nearest to its parent star.

The planet has a mean orbit of only 0.03 AU, which it completes in a mere 3 days.  Because of its short distance, the planet is too close to be within Gliese 581’s habitable zone.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>  It is unlikely to have an atmosphere because of the high temperatures and strong [[radiation]] it would receive at such a close distance to even a low mass [[star]].   

The planet has a mean orbit of only 0.03 AU, which it completes in a mere 3 days.  Because of its short distance, the planet is too close to be within Gliese 581’s habitable zone.<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref>  It is unlikely to have an atmosphere because of the high temperatures and strong [[radiation]] it would receive at such a close distance to even a low mass [[star]].   

==Old Universe View==

==Old Universe View==

In the cosmological model of a billions of years old universe, astronomers have calculated the star to be between 2 and 4.3 billion years old,<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> using measurements of Gliese 581’s kinematic characteristics and magnetic activity.  More recent measurements of the star shows its brightness only varies slightly over time, suggesting it is even older.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=5619</ref>

Liberal astronomers, who assume the cosmological model of a universe that is billions of years old, claim that the star is between 2 and 4.3 billion years old,<ref name="exo">http://exoplanet.eu/star.php?st=Gl+581</ref> using measurements of Gliese 581’s kinematic characteristics and magnetic activity.  More recent measurements of the star shows its brightness only varies slightly over time, suggesting it is even older.<ref>http://www.astronomy.com/asy/default.aspx?c=a&id=5619</ref>

[[Category:Astronomy]]

[[Category:Astronomy]]