A Planet for Every Star (And Then Some)

A Spotlight Into Space

Source: JPL News Release

Astronomers are rapidly closing in on the rather intriguing conclusion that there is on average at least one planet for every star in the Milky Way Galaxy  and probably a lot more than that.  The numbers are straighforward, but staggering. Approximately 100 billion stars give or take, yields a planetary count in the hundreds of billions.   Furthermore, the most recent study which came to this conclusion, conducted by a team at Cal Tech  based on data gathered by the prolific Kepler Space Telescope, centered on stars which aren’t even visible in the night sky to the naked eye.

The particular system in question is Kepler-32, a small M-Dwarf  type  star which is only half the size of our own sun, and emits primarily in the infrared range.   Nevertheless, it hosts a planetary system of at least 5 Earth sized planets, all of which are contained in orbit less than that of Mercury.  What makes this system unique as far as astronomers are concerned is the fact that the planets lie on an orbital plane in line with the star itself, making it possible to observe the system, and count the planets, from an edge-on perspective. The most relevant fact however, is that Kepler 32 is not unique at all, and is considered representative of most of the stars in our galaxy, leading to the overall estimate conservatively exceeding 100 billion.

Even though M-Dwarf systems may keep their planetary families close at hand, it does not necessarily mean that they cannot harbor the necessary conditions for hosting liquid water, and potentially life.  A star’s habitable zone is in relationship to overall output, meaning even with a system like that surrounding Kepler 32, the outermost of the  5 confirmed planets orbits on the edge of the zone.

Kepler, a Discovery class mission, was launched by a Delta II rocket in 2009, and following its primary 3.5 year lifespan,  received an extension from NASA in November which could carry it into 2016. After overcoming initial budget growth which threatened to derail the cost capped project, Kepler has literally produced more data than can be processed in a rapid fashion, leading to a rare degree of public outreach in attempting to analyze the data.