China has unveiled its latest plans for the world's biggest radio telescope—to look for habitable planets beyond our solar system by finding out if they have a magnetic field.
Published in the journal Research in Astronomy and Astrophysics, the team behind the Five-hundred-meter Aperture Spherical radio Telescope (FAST) has announced its ambitions for the next decade—including the hunt for exoplanets.
FAST, as the name suggests, is a 1,600 feet wide telescope. It sits in the Dawodang depression of the Guizhou Province and it achieved its first light in September 2016.
One of the main scientific missions of FAST is to listen out for pulsars and other interstellar radio signals—including any coming from hypothetical extraterrestrials. "In theory, if there is civilization in outer space, the radio signal it sends will be similar to the signal we can receive when a pulsar (spinning neutron star) is approaching us," Qian Lei, from the Chinese Academy of Sciences, told CCTV in 2016.
Many scientists looking for potentially habitable planets are focused on its composition (rocky), distance from its star (so liquid water can exist) and its atmosphere (that it has one). These are the requirements for life on Earth to exist—so may also be true of other planets.
But in their latest publication, FAST researchers from China and France said they are planning to look for exoplanets within 100 light years from Earth with magnetic fields.
Our own magnetic field protects the planet from the solar wind—a stream of charged particles from the Sun that would strip away our atmosphere without the magnetic field to deflect them.
The team believes that because Earth's magnetic field provides protection to life on the planet, it is reasonable to think the same may be true on other distant worlds.
"There is a scientific bug in the sci-fi blockbuster The Wandering Earth, that is, the Earth stops rotating. If that happens, the magnetic field would disappear," FAST chief scientist Li Di told Xinhua. "Without the protection of the magnetic field, the Earth's atmosphere would be blown off by the solar wind. As a result, humans and most living things would be exposed to the harsh cosmic environment and unable to survive."
Li said they could search for magnetic fields around exoplanets by looking for the interaction of the solar wind with the magnetosphere—an interaction that should generate radio radiation: "All the planets with magnetic fields in our solar system can be found generating such radiation, which can be measured and studied by radio telescopes. But research on the planets' magnetic fields cannot be realized through optical and infrared astronomical observation. Do the exoplanets have magnetic fields? If they have, they should also generate radio radiation under the influence of the wind of their parent stars."
He said if they can confirm the presence of a magnetic field using FAST, they would be able to study it to find out whether it was habitable or not. "It would be a very important discovery," he said.
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