Since the first planet outside of our solar system was discovered in 1994, astronomers have been hunting for an elusive target: a rocky planet roughly the size of the Earth that orbits its star at a distance that would allow liquid water to persist on its surface. In 2010, exoplanet hunters announced that they'd potentially found just such a planet. Twenty light-years away, orbiting the star Gliese 581, was a rocky planet thought to be three to four times the mass of the Earth, smack in the middle of the so-called “Goldilocks zone,” said the New York Times at the time.
Gliese 581g, as it became known, was our first candidate for an Earth-like planet—one that could potentially support life—in another solar system. Gliese 581g, and other planets that followed, have transformed our understanding of Earth's place in the universe.
Skip forward a few years, though, and suddenly Gliese 581g has fallen from its perch. According to new research, Gliese 581g doesn't actually exist, says physicist and science writer Matthew Francis for the Daily Beast.
Gliese 581g and its sibling planet Gliese 581d were spotted by watching how their gravitational pulls affected their parent star. Unfortunately for exoplanet fans everywhere, the wobbles thought to be the sign of Gliese 581g and d were actually the product of natural fluctuations on the star's surface, says Francis.
Magnetic events on the star Gliese 581, like the turmoil that causes sunspots to form on our star, were the source of the variability, says Elizabeth Howell for Universe Today.
Fortunately, the world of exoplanet hunters has moved on since Gliese 581g was first “detected.” Never fear, there are plenty more Earth-like planets to dream about blasting off to—for now, at least.