[meteorite-list] Starless planets may be habitable after all

From: Jeff Kuyken <info_at_meteoritecentral.com>
Date: Mon, 28 Feb 2011 20:24:34 +1100
Message-ID: <F1AA3AC12DB74D87BAD65D32C844D11A_at_JeffPC>

http://www.newscientist.com/article/mg20928005.200-starless-planets-may-be-habitable-after-all.html

Starless planets may be habitable after all.
20 February 2011

LIQUID water may survive on free-floating planets that have no star to warm
them. If they also support life, they could act as stepping stones to spread
life around the galaxy.

Gravitational tussles with other planets or passing stars can eject planets
from their solar systems. But even in the cold of space, these wayward
worlds could stay warm, thanks to the decay of radioactive elements in their
rocky cores.

Dorian Abbot and Eric Switzer of the University of Chicago calculate that
rocky planets with a similar mass to Earth could remain warm enough to keep
water liquid under thick, insulating ice sheets for over a billion years. A
planet with the same fraction of water as Earth could keep a subsurface
ocean liquid if it was 3.5 times Earth's mass. But a planet with 10 times
Earth's water concentration could do this if it weighed just one-third as
much as Earth, they say (arxiv.org/abs/1102.1108).

"It's a really interesting idea," says Lisa Kaltenegger of the
Harvard-Smithsonian Center for Astrophysics. "But we would have to land on
[a planet] and burrow down to see if life is possible."
Received on Mon 28 Feb 2011 04:24:34 AM PST