On Monday, NASA acknowledged it was a tiny step closer to discovering life may exist elsewhere in the universe. NASA released a list of 219 new “planet candidates” discovered by the Kepler space telescope, which was searching for planets orbiting other stars in the constellation Cygnus. Ten of those planets are similar to Earth’s size and reside in their star’s “habitable zone.” The “habitable zone” is the area in a distance from a star where liquid water can pool.
According to JPL, the Kepler space telescope looks for planets by detecting the tiny drop in a star’s brightness that occurs when a planet crosses in front of it, called a transit.
JPL explained:
To ensure a lot of planets weren’t missed, the team introduced their own simulated planet transit signals into the data set and determined how many were correctly identified as planets. Then, they added data that appear to come from a planet, but were actually false signals, and checked how often the analysis mistook these for planet candidates. This work told them which types of planets were overcounted and which were undercounted by the Kepler team’s data processing methods.
Susan Thompson, Kepler research scientist for the SETI Institute in Mountain View, California, and lead author of the catalog study, stated, “This survey catalog will be the foundation for directly answering one of astronomy’s most compelling questions: How many planets like our Earth are actually in the galaxy?”
Benjamin Fulton, doctoral candidate at the University of Hawaii in Manoa, and lead author of the second study, noting the two distinct groupings of small planets that were as small as Earth or as large as Neptune, which is roughly four times the size of Earth, added, “We like to think of this study as classifying planets in the same way that biologists identify new species of animals. Finding two distinct groups of exoplanets is like discovering mammals and lizards make up distinct branches of a family tree.”