Landmark discovery made by American space agency
On Jan. 6, 2015, the American National Aeronautics and Space Administration (NASA) announced that its Kepler spacecraft had recently identified its 1000th exoplanet since its launch in 2009. The spacecraft is designed to map out a portion of the Milky Way in order to examine the number of planets outside of our solar system orbiting around their suns’ habitable zones in our galaxy.
Scientists at NASA analyzed Kepler data and concluded that at least eight more exoplanet candidates were, in fact, planets orbiting stars. Of the eight identified planets, three are located in their suns’ habitable zone, and two of these three are most likely made of rock – like Earth.
Exciting is that the two rocky planets – Kepler-438b and Kepler-442b – are less than 1.5 times the diameter of Earth. Kepler-438b is 475 light-years away, and is 12 per cent larger than Earth, while Kepler-442b is 33 per cent larger than Earth, and is 1,100 light-years away. A single light-year is the distance that light travels in a single Earth year, and is calculated to approximately 10 trillion kilometres.
“Each result from the planet-hunting Kepler mission’s treasure trove of data takes us another step closer to answering the question of whether we are alone in the Universe, said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate at the agency’s headquarters in Washington, in a press release. “The Kepler team and its science community continue to produce impressive results with the data from this venerable explorer.”
Additionally, the Kepler team has added 554 candidates to the list of potential planets, bringing the total list of candidates to 4,175.
“With each new discovery of these small, possibly rocky worlds, our confidence strengthens in the determination of the true frequency of planets like Earth, said Doug Caldwell, SETI Institute Kepler scientist at NASA’s Ames Research Centre at Moffett Field, in the same press release. “The day is on the horizon when we’ll know how common temperate, rocky planets like Earth are.”
The Habitable Zone is described as a precise area of space that a planet must orbit in order to sustain terrestrial life. The habitable zone is sometimes called the Goldilocks zone, because it is a region of space that is “just right.”
For all other stars, the habitable zone is calculated using information about the Earth’s biosphere, as well as the Earth and sun’s mass.
Kepler uses a photometer that monitors the brightness of over 145,000 main sequence stars in order to determine information about any possible orbiting planetary bodies. For the bodies identified as planets, their composition is determined using calculations based on the planet’s distance from its star, as well as general assumptions about the formation of planets.
“Kepler collected data for four years – long enough that we can now tease out the Earth-size candidates in one Earth-year orbit,” said Fergal Mullally, SETI Institute Kepler scientist, in the same press release. “We’re closer than we’ve ever been to finding Earth twins around other sun-like stars. There are the planets we’re looking for.”