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's magnetic field may produce radio signals from auroras in the planet's atmosphere. While current telescopes have yet to pick up these crackles, it's an area worth exploring, argue Joseph Lazio at the Naval Research Laboratory in Washington DC and colleagues in a paper submitted to Astro2010.
Because a magnetic field helps to preserve atmospheres and oceans, a magnetosphere may signify that a planet has complex surface life. "This is something we think is worth studying at a modest level," says Lazio, "the payoff could be immense."
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's atmosphere would absorb the low frequency signals.
That leads some planet hunters to doubt the idea's feasibility. We have never directly detected the magnetosphere from any extrasolar planet, despite strong efforts, says Geoff Marcy of the University of California, Berkeley. 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's magnetic field indirectly by studying its host star. "It's an exciting proposal," he says.
When struck by high energy particles in the solar wind, an exoplanet's magnetic field may produce radio signals from auroras in the planet's atmosphere. While current telescopes have yet to pick up these crackles, it's an area worth exploring, argue Joseph Lazio at the Naval Research Laboratory in Washington DC and colleagues in a paper submitted to Astro2010.
Because a magnetic field helps to preserve atmospheres and oceans, a magnetosphere may signify that a planet has complex surface life. "This is something we think is worth studying at a modest level," says Lazio, "the payoff could be immense."
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's atmosphere would absorb the low frequency signals.
That leads some planet hunters to doubt the idea's feasibility. We have never directly detected the magnetosphere from any extrasolar planet, despite strong efforts, says Geoff Marcy of the University of California, Berkeley. 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's magnetic field indirectly by studying its host star. "It's an exciting proposal," he says.
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