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Location: UFOUpDatesList.Com > 2013 > Nov > Nov 5

One In Five Milky Way Stars Have 'Earths'

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

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

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.


[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]


Ray D

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