Cited Works
Boss, Alan (1998) Looking for Earth: The Race to Find New Solar Systems. New York. Johh Wiley & Sons, Inc.
Freedman, Roger A. and William Kaufman (2005) Universe. Seventh edition. New York. W. H. Freeman and Company.
Kutter, G.S (1987) The Universe and Life: Origins and Evolution. Boston. Jones and Bartlett Publishers, Inc.
Ward, Peter and Donald Brownlee (2000) Rare Earth: Why Complex Life is Uncommon in the Universe. New York. Copernicus Books.
"Gliese 581 c" Retrieved June 15, 2007 from Wikipedia.
http://en.wikipedia.org/wiki/Gliese_581_c#Discovery
W. Von Bloh, et. al. The Habitability of Super-earths in Gliese 581. May 25, 2007.
http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.3758v1.pdf
(Discusses the proposal that 581c might have runaway greenhouse gases therefore making 581d in the habitable zone)
Comments: