Concept drawing of HD 219134b transiting its star. Image: NASA/JPL-Caltech
This week, NASA announced the discovery of the nearest rocky exoplanet ever found, located about 21 light years away in the constellation Cassiopeia. Dubbed HD 219134b, the alien world is about 1.6 times the size of Earth, and is already shaping up to become an invaluable research tool for scientists."Transiting exoplanets are worth their weight in gold because they can be extensively characterized," said Michael Werner, the project scientist for the Spitzer Space Telescope, in a NASA statement. "This exoplanet will be one of the most studied for decades to come."The news dropped just a week after NASA announced the discovery of Kepler-452b—the most Earth-like planet ever detected. With its 385-day year, its Sun-like host star, and its position smack-dab in the middle of the Goldilocks zone, the planet is a compelling candidate in the search for alien life.Concept animation of HD 219134b. Video: NASA Jet Propulsion Laboratory/YouTubeThat said, Kepler-452b is 1,400 light years from Earth, so it will be much more difficult to study with the same precision as HD 219134b. "Most of the known planets are hundreds of light-years away," said astronomer Lars A. Buchhave, who co-authored the new research. "This one is practically a next-door neighbor."In other words, what HD 219134b lacks in hospitality to life, it makes up for in proximity to Earth. To that end, scientists are already planning to resolve the planet in finer detail with the powerful new generation of telescopes set to come online over the next decade.The last 20 years have completely revolutionized our understanding of planets beyond our own solar system. But as this spate of new discoveries demonstrates, the exoplanet party is just getting started.
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