The next time you take a moonlit stroll, or admire a full, bright-white moon looming in the night sky, you might count yourself lucky. New observations from NASA's Spitzer Space Telescope suggest that moons like Earth's -- that formed out of tremendous collisions -- are uncommon in the universe, arising at most in only 5 to 10 percent of planetary systems.

"When a moon forms from a violent collision, dust should be blasted everywhere," said Nadya Gorlova of the University of Florida, Gainesville, lead author of a new study appearing Nov. 20 in the Astrophysical Journal. "If there were lots of moons forming, we would have seen dust around lots of stars -- but we didn't."

It's hard to imagine Earth without a moon. Our familiar white orb has long been the subject of art, myth and poetry. Wolves howl at it, and humans have left footprints in its soil. Life itself might have evolved from the ocean to land thanks to tides induced by the moon's gravity.



Check out the rest: \spitzer.caltech.edu/Media/releases/ssc2007-18/release.shtml

5-10% aren't bad odds. When you consider :

Scientists believe the moon arose about 30 to 50 million years after our sun was born, and after our rocky planets had begun to take shape. A body as big as Mars is thought to have smacked into our infant Earth, breaking off a piece of its mantle. Some of the resulting debris fell into orbit around Earth, eventually coalescing into the moon we see today. The other moons in our solar system either formed simultaneously with their planet or were captured by their planet's gravity.

http://www.spitzer.caltech.edu/Media/releases/ssc2007-18/release.shtml


Earth would have been noticeably bigger without what was lost in the collision and what ended up in our Moon. With this and without the moon's influence in steadying our world, who knows what would have happened, regarding life on Earth :

http://astrobio.net/news/modules.php?file=article&mode=thread&name=News&op=modload&order=0&sid=2507&thold=0


Would we be here now?

Hum
Uncommon, but not that uncommon.

But, it should be said that the combination of the right type of star, being in the habitable zone, and having the right composition, do add to the earth being quite special place (as opposed to the charon pluto system).

earths super rotation might have been a problem tough a day was 18 hours yus 200 million years ago I believe have to look it up tough, anyway it's been slowing down ever since the moon I'm not sure what the effects would be of a day less then 8 hours long their probably would be quit a bulge in the the atmosphere

Hum,
i suspect that you are thinking of the lunar tide cycle of 18 hours which may have been during the precambrian era (say 5 billion to 570 million years ago) when the Moon was a lot closer.
But , the Earths spin would not have been slowed down by much; say from 22 hours.

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hum, not according to this though:
http://www.angelfire.com/tx5/blackdraxon/how_long_is_a_day.htm
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