During the three or so years since launch NASA’s Kepler Space Telescope has discovered many new planets outwith our solar system – exoplanets. NASA has announced that Kepler will continue boldly seeking out new celestial bodies, at least till 2016.
When it was launched on March 6 2009, no-one could have predicted just how successful the Kepler Space Telescope would be in identifying planets beyond our solar system. Since launch, Kepler has zoomed in on over 2,300 planetary candidates awaiting further research for possible positive identification as planets and spotted in excess of 100 confirmed planets orbiting stars other than our sun.
Kepler has confirmed what was long suspected by astronomers – our solar system is by no means unique, rather, the Universe is highly efficient when it comes to planets rolling off the production line.
To date, Kepler has found hundreds of Earth-size planets many of which may orbit a star’s habitable zone – that Goldilocks band of space in a solar system which is neither too hot nor too cold, but, in theory at least, just right for water to exist in liquid form enabling life to live long and prosper.
With the initial 42 month Kepler mission reaching a close, NASA has announced an extension whereby Kepler will focus on collecting data with a view to discovering true Earth-like equivalents – rocky planets, roughly the same size as Earth, taking approximately one Earth year to orbit stars of similar magnitude (size and brightness) to our own Sun.
Kepler’s methodology for researching exoplanets is relatively simple. When a possible planet passes in front of its parent star, light from the parent star is blocked. Kepler uses this differential to gauge the size of a potential planet – the bigger the planet the more light is blocked. From that the size of a planet relative to its parent star can be calculated. With further advances in technology used for imaging and data calibration a clearer picture of exoplanets, including those with the potential to harbour life, may be expected to emerge over the next few years.
Says William Borucki, Kepler principal investigator at NASA's Ames Research Center in Moffett Field, Calif., "The initial discoveries of the Kepler mission indicate at least a third of the stars have planets and the number of planets in our galaxy must number in the billions. The planets of greatest interest are other Earths, and these could already be in the data awaiting analysis. Kepler's most exciting results are yet to come."
Over the last three years, Digital Journal has regularly reported on some of the Kepler Space Telescope’s stunning discoveries.
NASA's Kepler mission has discovered a world where two suns set over the horizon instead of just one. The planet, called Kepler-16b, is the most "Tatooine-like" planet yet found in our galaxy and is depicted here in this artist's concept with its two stars.
In September 2011, imaging from the Kepler Space Telescope revealed a planet reminiscent of the fictional planet Tatooine of Star Wars fame, a circumbinary planet in orbit around a two star (binary) system. Such planets had previously existed only in astronomical theory (and science fiction) but Kepler data confirmed the existence of the new gas giant labelled Kepler-16b.
In December 2011, Digital Journal highlighted one of the best prospects yet for an Earth-like planet, designated Kepler 22-b, located within a solar system’s Goldilocks zone in a star system 600 light years from Earth. Hardly next door to us but as technology races ahead, there is the tantalising prospect of more Earth 2.0’s being discovered in star systems much closer to home. At present, whilst it has become relatively easy to spot large Jupiter-like gas giant type planets orbiting other suns, picking out planets resembling our own, much smaller, third rock from the sun is trickier.
This diagram compares our own solar system to Kepler-22, a star system containing the first "habitable zone" planet discovered by NASA's Kepler mission. The habitable zone is the sweet spot around a star where temperatures are right for water to exist in its liquid form. Liquid water is essential for life on Earth. (NASA)
These and other milestones in the Kepler Space Telescope’s mission to date are also highlighted in the NASA announcement confirming Kepler’s extended mission to search for new planets right through to 2016.
"Kepler's bounty of new planet discoveries, many quite different from anything found previously, will continue to astound. But to me, the most wonderful discovery of the mission has not been individual planets, but the systems of two, three, even six planets crowded close to their stars, and, like the planets orbiting about our sun, moving in nearly the same plane. Like people, planets interact with their neighbors and can be greatly affected by them. What are the neighborhoods of Earth-size exoplanets like? This is the question I most hope Kepler will answer in the years to come," said Jack Lissauer, planetary scientist at the Ames Research Center.
Geoff Marcy, professor of astronomy at the University of California at Berkeley, neatly encapsulated Kepler’s discoveries to date as demonstrating that not only is the Universe stranger than we imagined, but it’s stranger than we could ever imagine we could imagine, saying, “The Earth isn't unique, nor the center of the universe. The diversity of other worlds is greater than depicted in all the science fiction novels and movies. Aristotle would be proud of us for answering some of the most profound philosophical questions about our place in the universe."
Astronomers, whether professional or amateur, can look forward to the Kepler Space Telescope boldly going on its continuing mission for another four years. Let’s see what’s out there!