I am an aspiring amateur astronomer. That is, I aspire to have enough time to even be considered an amateur in this field. I have a small telescope, several books, a pair of gigantic binoculars, and a subscription to Sky & Telescope. Of these, the subscription gets the most use.
Anyway, I ran across this little entry noting some new discoveries that indicate the earth's privileged status is the result of even more unique processes than we knew:
Genesis: Earth is Weird
When NASA's Genesis spacecraft crash-landed in the Utah desert in 2004 after collecting samples of the solar wind, the mission seemed lost. But scientists have painstakingly salvaged the solar-wind samples, and these tell an odd story.
The Sun's oxygen-isotope ratios don't match Earth's. Instead, they match those of the earliest meteorites. So, when the solar system was forming, it's Earth that somehow became the oddball, not the meteorites as scientists had assumed. Now there is "no plausible model" to make Earth with the oxygen ratios it exhibits. Kevin McKeegan (UCLA) told the Lunar and Planetary Science Conference in March. "It's always been a challenge to supply Earth with the water it has. Now we're wondering how it got the rocks it has."
Sky & Telescope, July 2008, page 16.