From: Ray Dickenson <r.dickenson.nul> Date: Tue, 5 Nov 2013 12:13:12 -0000 Archived: Tue, 05 Nov 2013 09:12:22 -0400 Subject: One In Five Milky Way Stars Have 'Earths' Hello List, If you want to calculate the number of Earth-type planets around us, there are problems with this press release from the Keck Observatory. One is their estimate of the number (100 billion) of stars in the Milky Way. On the Web one can find 'official' estimates ranging up to 600 billion, and one recent calculation, which takes the distribution curve of star-masses into account, is over one trillion. They do the sums by calculating the total mass of the Galaxy (by its rotation rate) and then dividing that by what they think is the 'average' star mass - which accounts for the wide range of results. But for me the main problem is that most modern calculations first subtract about 85% - 90% of the Milky Way mass as being "dark matter" and not stars at all - which for us dark matter sceptics is a step too far. So, as the initial mass calculation says the Milky Way weighs up to two trillion times our Sun's mass, it's anybody's guess how many Earth-type stars there are. My own guess is around 100 to 200 billion. http://tinyurl.com/nmss8e9 [Quotation Begins] "Scientists from University of California, Berkeley, and University of Hawaii, Manoa, have statistically determined that twenty percent of Sun- like stars in our galaxy have Earth-sized planets that could host life. The findings, gleaned from data collected from NASA's Kepler spacecraft and the W. M. Keck Observatory, now satisfy Kepler's primary mission: to determine how many of the 100 billion stars in our galaxy have potentially habitable planets. The results are being published November 4 in the journal Proceedings of the National Academy of Sciences. "What this means is, when you look up at the thousands of stars in the night sky, the nearest sun-like star with an Earth-size planet in its habitable zone is probably only 12 light years away and can be seen with the naked eye. That is amazing," said UC Berkeley graduate student Erik Petigura, who led the analysis of the Kepler and Keck Observatory data." [Quotation Ends] Cheers Ray D Listen to 'Strange Days... Indeed' - The PodCast At: http://www.virtuallystrange.net/ufo/sdi/program/ These contents above are copyright of the author and UFO UpDates - Toronto. They may not be reproduced without the express permission of both parties and are intended for educational use only.
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