ALIEN worlds that are friendly to life could reveal themselves by radio signals crackling from their magnetic fields.
When struck by high energy particles in the solar wind, an exoplanet鈥檚 magnetic field may produce radio signals from auroras in the planet鈥檚 atmosphere. While current telescopes have yet to pick up these crackles, it鈥檚 an area worth exploring, argue Joseph Lazio at the Naval Research Laboratory in Washington DC and colleagues in submitted to .
Because a magnetic field helps to preserve atmospheres and oceans, a magnetosphere may signify that a planet has complex surface life. 鈥淭his is something we think is worth studying at a modest level,鈥� says Lazio, 鈥渢he payoff could be immense.鈥�
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The snag is that we would need a space telescope 100 times as sensitive as any planned to find auroras within a few dozen light years, because the Earth鈥檚 atmosphere would absorb the low frequency signals.
That leads some planet hunters to doubt the idea鈥檚 feasibility. We have never directly detected the magnetosphere from any extrasolar planet, despite strong efforts, says . Yet planetary magnetospheres would be easier to spot at radio frequencies than planets themselves, says Gordon Walker of the University of Victoria in British Columbia, who has spotted an exoplanet鈥檚 magnetic field indirectly by studying its host star. 鈥淚t鈥檚 an exciting proposal,鈥� he says.
