William Atkins
Tuesday, 21 April 2009 23:57
Science -
Space
Page 2 of 3
What is especially interesting about this newly discovered planet is the possibility that it may contain a huge ocean that covers all, or nearly all, of the planet.
Dr. Mayor states,
"It is the only low-mass planet known inside the habitable zone [of Gliese].” [New Scientist: “
Sibling worlds may be wettest and lightest known”]
He adds, “
The holy grail of current exoplanet research is the detection of a rocky, Earth-like planet in the ‘habitable zone’ — a region around the host star with the right conditions for water to be liquid on a planet’s surface.” [ScienceDaily.com: “
Lightest Exoplanet Yet Discovered”]
The other three known planets of Gliese are Gliese b, Gliese c, and Gliese d.
Gliese 581 b is the second closest planet to the star, with a mass of at least 15.7 Earths, which is similar to the mass of the planet Neptune. It was discovered in August 2005 with an orbital period of about 5.4 Earth-days.
Gliese 581 c, which was discovered in April 2007, has a mass that is at least equal to five Earths (about one-third the mass of Neptune). It is thought to have a massive greenhouse-type atmosphere (like the planet Venus in our Solar System), so it unlikely to be inhabitable.
This planet is thought to be rocky with a radius about 1.3 times that of Earth. It completes an orbit in about 12.9 Earth-days.
Page three concludes with more information on "d".
