On 7th March, 2009, NASA launched the Kepler space observatory into an Earth-trailing heliocentric orbit. Recently, 219 new exoplanets have been found, courtesy Kepler. This brings the total from its journey in space to 2,335 discovered exoplanets with a potential of 1,699 more. Out of all of these discovered exoplanets, 49 of them seem to be within their star’s habitable zone, with over 30 of them so far being confirmed.
Many of these planets are known as a “Super-Earth” and fall into two different size categories: < 1.5x the size of Earth with a rocky composition, and > 2x the size of Earth with a gaseous composition. Very rarely do any of the planets fall in-between these two different sizes. It’s these smaller rocky planets that pose the potential to host life.
A super-Earth generally has a mass greater than that of Earth, whilst being substantially less massive than gas giants such as Neptune and Uranus. Whilst the term does not specifically refer to criteria such as composition or habitability, planets on the lower end of this mass scale are generally rocky in nature. The more massive the planets get, the more likely they are to be gaseous.
“The Kepler data set is unique, as it is the only one containing a population of these near Earth-analogues – planets with roughly the same size and orbit as Earth,” explained Mario Perez, a Kepler program scientist in the Astrophysics Division of NASA’s Science Mission Directorate. “Understanding their frequency in the galaxy will help inform the design of future NASA missions to directly image another Earth.”
HOW DOES THE KEPLER TELESCOPE WORK?
The telescopes examines stars consistently and monitors the light that they are emitting. Even the smallest change in light can be detected. A small drop in the star’s brightness would indicate that a planet is moving past it, in what’s known as a transit.
To ensure that as many planets were correctly identified as possible, the accuracy of the data analysis had to be examined.
Simulated planet transit data was inserted into the data set to see if they were correctly identified as planets. False signals were then added to the data to see if they were mistakenly analyzed as a planet transit. This helped the researchers know how accurate the data analysis was.
“We like to think of this study as classifying planets in the same way that biologists identify new species of animals,” said Benjamin Fulton, doctoral candidate at the University of Hawaii in Manoa and the lead author in a second study closely related to this exoplanet discovery.
A lot of research is currently happening into the exploration of extra-terrestrial life. Whether it’s Kepler, Juno or the Mars Rover; all play an important role in space exploration. With each new piece of information, however big or small, the possibility of finding life on other planets becomes more and more plausible.