Messenger Data Says Mercury's Magnetic Past Goes Back Billions of Years

Space.com notes a study published in the May 7th issue of Science (abstract) which concludes not only that Mercury has a magnetic history dating back billions of years, but also that the strength of that field means that it once rivaled Earth's own magnetic field, though it is now "about 100 times weaker." The source of this conclusion is data gathered prior to the crash of NASA's Messenger probe into Mercury's surface on April 30 of this year. Says the story: The researchers analyzed magnetic data collected by MESSENGER in the fall of 2014 and 2015, when the spacecraft flew incredibly close to the planet's surface, at altitudes as low as 9 miles (15 kilometers). In contrast, the lowest that MESSENGER flew in previous years was between 125 and 250 miles (200 and 400 km). ... The scientists detected magnetized rocks in a part of Mercury's crust that, due to the presence of many craters from cosmic impacts, appears to be quite ancient. The researchers suggest the rocks were once magnetized by the planet's magnetic field, and based on the age and amount of the magnetized rocks, as well as how strongly they were magnetized, the investigators deduced that Mercury's magnetic field has persisted for 3.8 billion years.

Re:

[antiperimetaparalogo]

it stopped spinning.

Yes, based on the dynamo theory [wikipedia.org], the core stoped spinning, so no generation of magnetic field.

Re:

[PPH]

Possibly due to tidal locking [wikipedia.org]

Re:

[antiperimetaparalogo]

Hmmm... i think your comment is more correctly/accurately related to Mercury's generation (or not) of magnetic field than mine!

Re:

[X0563511]

That close to the sun, however... isn't it possible for the core to have some convective motion?

Re:

[PPH]

convective motion

Yes. But that might not be moving in the correct direction to produce a magnetic field external to the core. Fleming's right hand rule [wikipedia.org] and all that.

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[Tablizer]

it stopped spinning.

Quick, elect it!

Someone installed systemd.

[Hognoxious]

They tried to restart the core-spin service, but something was in an inconsistent state and they couldn't read the stupid binary logs to find out what.

heh.

[Black Parrot]

n the fall of 2014 and 2015, when the spacecraft flew incredibly close to the planet's surface, at altitudes as low as 9 miles (15 kilometers)

I do believe it flew a lot closer than that in 2015.

Solar wind interactions

[Gary Perkins]

If I remember correctly, auroras here on Earth are produced by charged particles being funneled into the atmosphere by our magnetic field, and the lights are produced by ionization of various elements in the process. However, I can't help but wonder if there would be any observable effects of a strong planetary magnetic field so close to the sun? In other words, would Mercury appear any different than it does now in our sky, viewed either against black space or as it traverses across the Sun?

Good thing.

[nospam007]

So when can we expect mercury harddisks?

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[vandamme]

They're not popular, because you have to keep them below -40 degrees (F or C) or they melt.