Everyone knows there are billions and billions of stars. On a clear night, one can see evidence of their existence scattered across the night sky. What is a little less clear is how many planets exist. Until recently, most scientists thought planets relatively uncommon. As reported in The New York Times (Science: January 11, 2012), however, several new studies have shown that there may actually be more planets than stars. Scientists used a few different ways to detect the presence of planets around stars outside our solar system. NASA scientists used a space-based telescope to detect planets. This telescope can detect planets as small as Earth and planets quite close to their sun.
Others examine the brightness of stars as seen by several land-based telescopes to infer the presence of planets. This method is good for detecting larger planets usually a bit farther from their sun. The surprising find is that many stars in the Milky Way have planets. Evidently, most do and very conservative estimates suggest that on average stars in the Milky Way have at least 1.6 planets. According to the article, the existence of more than 700 exoplanets, planets outside our solar system, has already been confirmed. Thousands are waiting independent confirmation.
Planets have even been detected around stars thought very unlikely to have a planet. For example, planets have been found around solar systems with two stars. Somehow, the planets are not destroyed by the competing gravitational fields. Given that the Milky Way has more than 100 billion stars, the likelihood of finding a planet with similar characteristics as Earth seems much more likely. If so, scientists may have to brush up on their Greek mythology, as there will be plenty of naming opportunities.
Noted by WVR, MD
*This filler excerpt can be found in the April 2012 Pediatrics print journal p. 744, or via online here.
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