Jupiter’s moon Io — the solar system’s most volcanic world — has inspired a new way to find distant exoplanets. As the moon orbits Jupiter, it tugs on the planet’s magnetic field, generating bright auroras in Jupiter’s atmosphere. Even if we couldn’t see Io itself, the enormous auroras, pulsing to the beat of a hidden orbiting body, would tell us that something was out there.
Scientists have long suspected that a similar process might be at work with distant planets and the stars they orbit. Now, for the first time, astronomers say they have discovered an exoplanet by mapping the auroras of its host star, opening a new chapter in the quest to map the galactic menagerie of unseen worlds.
In the new study, published yesterday in Nature Astronomy, researchers used a collection of roughly 20,000 small radio antennas spread across Europe to detect the star’s telltale flares. They concluded that the flares could only be produced by a rocky planet about the size of Earth that takes between one and five days to orbit the star. Such a planet would be right at the edge of the star’s habitable zone, where temperatures are right for liquid water.
As with so many new techniques, this one promises more discoveries to come. “This could be a way of discovering more exoplanets than you can with the traditional methods,” said Jonathan Nichols, an astrophysicist at the University of Leicester who was not involved in the research. “It could be a way of probing the types of system that we usually find quite difficult to observe.”
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