Recently I read an article put out by the Associated Press headlined as “Cosmic census finds crowds of planets in our galaxy”. Being new to this whole blog thing and having just found access to the site I felt pretty lame when I saw that this article had been posted about by Angus and other commenters. Nevertheless having spent time writing this on the plane with my knees at my chin (economy row) and being very proud that I was going to get this posted.. here it goes.
The article starts out by giving some “astronomical” number of planets that are estimated within our Milky Way. Researchers estimate that there are “at least 50 billion planets in the Milky Way”. Of those, they estimated that some 500 million planets are in the not-too-hot, not-too-cold “Goldilocks zone” where life could perhaps exist. The basis for these estimates comes from the data collected by NASA’s Kepler telescope with the research being headed by the Kepler Science Chief – William Borucki. The research concentrated on only 1/400th of the available night sky and extrapolated the estimates from their findings. Within this sliver of observed sky, Kepler has so far found 1,235 candidate planets, with 54 in the Goldilocks zone. The method used by Kepler researchers is to fix on a distant star and watch for anything that may block the star’s light such as a rotating planet about the star.
Based on the figures, further estimates were made that for every two stars, one star could be expected to have planets in the habitable zone. These ratios were announced recently at the American Association for the Advancement of Science annual conference in Washington.
The article goes on to say that for many years astronomers figured that there were 100 billion stars in the Milky Way, but now it is believed by at least one Yale University researcher that there may be around 300 billion stars within our home galaxy. Also, stated is that there is an estimated 100 billion galaxies in the now known universe.
With these kinds of numbers and the fact that there may be many places for other life to exist, the reporter asked Borucki why these life forms have not contacted us. The answer from Borucki, “I don’t know”.
Brian Morgan
Texas A&M – Commerce
Astronomy 561
3/11/11
I was wondering if the "Goldilocks" zone applies only to stars similar to the Sun or if it would be a closer distance to a red giant or would the gravitational effects of being close to a red giant make it outside this possibility. Does Goldilocks apply to temperature for water alone?
ReplyDeleteWell, Wikipedia doesn't know either, Jeff....
ReplyDelete"... a planet following this Goldilocks Principle is one that is neither too close nor too far from a star to rule out liquid water on its surface and thus life (as humans understand it) on the planet. However, planets within a habitable zone that are unlikely to host life (e.g., gas giants) may also be called Goldilocks planets. The best example of a Goldilocks planet is the Earth itself. "
from http://en.wikipedia.org/wiki/Habitable_zone
Yes, that's right - Goldilocks does apply to any star, including red giants, etc. The thing I can immediately think of that would prevent life arising on a planet in the Goldilock's zone around a giant star is the lifetime of the star - a giant star will have a much smaller lifetime than our sun, or else be at a much more advanced stage of its life, and so the time for life to arise, and indeed intelligent life, is much smaller.
ReplyDelete