By Shining a Laser From the Ground, Researchers Could Easily Measure Earth's Magnetic Field

Firing Lasers at the Sky Dmitry Budker lab/UC Berkeley

To map the earth’s magnetic field, scientists usually take readings from one of a number of satellites, a process that is expensive and often less-than accurate. Physicists at UC Berkeley have a better idea: measure the earth’s magnetic nuances using a single ground-based laser to examine the spin of sodium atoms 56 miles up in the sky.

There are a variety of reasons for mapping the Earth’s magnetic field--geophysicists use the data to study the planet’s interior, oil and gas companies use it to hunt for energy deposits, and climatologists use it to study changes in the atmosphere. Studying the atmosphere, it turns out, should inform scientists about changes in the earth’s magnetic field as well.

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Science, Clay Dillow, atmospheric science, earth's magnetic field, environment, geology, planetary geologist

Aiming a precisely tuned 20- to 50-watt orange laser at a six-mile-thick band of sodium atoms in the mesosphere (some 56 miles up) excites the atoms, causing them to fluoresce. The degree of fluorescence depends on the spin polarization of the atoms when the laser strikes them, allowing researchers on the ground to take measurements from which they can determine the magnetic field at that point in space.

At least, that’s the theory. ESO researchers who collaborated on the idea are developing a 20-watt modulated laser that will be deployed at the Very Large Array in Chile’s Atacama Desert to test the idea.

[PhysOrg]