Since the first discoveries of planets beyond Earth and our solar system, the human imagination has been fascinated by the idea of extraterrestrial life. In recent years, astronomers spurred by the possibility of finding planetary environments conducive to life have overlooked the seemingly simple task of identifying and confirming new candidates.
On Feb. 26, NASA’s Kepler team announced a breakthrough discovery of 715 new planets. Co-led by Jack Lissauer, a scientist at NASA’s Ames Research Center, the team applied an analysis technique based on the logic of multiplicity to planet candidates in multi-planetary systems.
To identify possible planets, the research team observed a few thousand stars out of 160,000 that appeared to be associated with planet candidates. Of those few thousand, a sub-category of hundreds of stars was identified as forming parts of multi-planetary systems. By analyzing the brightness of the stars, particularly looking for dimming caused by planets orbiting in front of the stars, the Kepler team was able to identify potential planet candidates.
This method alone, though, proved insufficient. The maze of stars was difficult to interpret simply by brightness. In fact, this brightness analysis did not account for the possibility that dim stars moved in front of brighter ones, thereby blocking light and imitating the dimming effect produced by a planet.
To address this problematic aspect of the investigation, the team devised a statistical technique that relied upon the principle of multiplicity. Before the development of this method of authentication, planet candidates had to be confirmed one by one. Now, by using this multifaceted approach, many planets can be evaluated at once.
The principle of multiplicity is best explained through an astronomer-created metaphor: The arrangement of planets in a multi-planetary system is likened to the group organization of lions. For the Kepler research team, the stars were comparable to the lions, and the planet candidates were lionesses. If two large felines were observed, the pair could consist of two lions or one lion and one lioness. If more than two felines were observed, the researchers assumed the conglomeration was a pride, which consists of a single lion accompanied by a host of lionesses. In this way, the researchers were able to verify planets in a multi-planet group.
Of the newly identified planets, almost 95 percent are thought to be less than four times the size of Earth. Furthermore, four of these planets were found to be located within their respective stars’ habitable zone, the range in which the surface temperature of a planet is favorable for the presence of water.
A particularly interesting planet among those newly identified is Kepler-296f. Twice the size of Earth and orbiting a star half the size of the Sun, this planet seems to have conditions hospitable for water. Thus, Kepler-296f may likely be the subject of further scientific inquiry.
In its achievement of uncovering 715 new worlds through inventive analysis techniques, NASA’s Kepler research group opens up a wide spectrum of queries. The most prominent among these is the possibility of finding extraterrestrial life. As the application of the team’s methods becomes more widespread, the likelihood of finding significant truths of the cosmos will only increase.
