Magnetic Twisters "Dance" Across Mercury, Study Says

Rebecca Carroll
for National Geographic News
April 30, 2009

The ever-present supersonic gale from the sun creates never-before-seen magnetic "twisters" that "dance" across Mercury's magnetic field and occasionally touch down on its surface, new observations have revealed.

These invisible formations, made of high-energy electrons, kick up material from Mercury's surface and send it flying into the tiny, rocky planet's tenuous atmosphere, according to new research.

Part of a suite of new findings based on October 2008 data from the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, the study could help explain why Mercury's thin, inconstant atmosphere is so, well, mercurial.

The findings, published this week in the journal Science, could also add to scientists' understanding of the phenomenon called space weather.

With a period of strong solar storms predicted to start in 2012 that could interfere with satellites and disrupt power grids on Earth, better understanding of solar wind is a pressing need, scientists say.

(Related: "Magnetic-Shield Cracks Found; Big Solar Storms Expected.")

Surprisingly Intense

Mercury's magnetic twisters are created when solar wind—which is actually a stream of charged particles—triggers a process on the tiny planet called magnetic reconnection.

This is when magnetic field lines flowing from the sun splice together with the field lines around Mercury.

The connection transfers solar wind energy into the planetary magnetic field and sends charged particles shooting toward the planet along the field lines.

Bundles of these connected field lines then penetrate the planet's magnetic boundary and their particles are sent whirling by the solar wind, forming the twisters.

On Earth, energy from magnetic reconnection "lights up" atoms in our much thicker atmosphere, creating the shimmering auroras at our planet's poles.

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