Tuesday, December 16, 2008

NASA Stuff

Mon cher Paw sent me the link to this video over at Open Culture. The notes say, "Astronaut Don Pettit created this remarkable video of the aurora borealis (otherwise known as The Northern Lights)... by stitching together a large sequence of still images that he took from space." The thing in the upper left is part of the International Space Station.

But as cool as that is, NASA informed me today that there's "a giant breach in Earth's magnetic field." I find this alarming. At least I think I would, if I were sure I understood what they're saying.

NASA's five THEMIS spacecraft have discovered a breach in Earth's magnetic field ten times larger than anything previously thought to exist. Solar wind can flow in through the opening to "load up" the magnetosphere for powerful geomagnetic storms.

Not knowing if "powerful geomagnetic storms" are a problem, I looked it up and found this description:

"A G4 [second highest rating on NOAA scale] geomagnetic storm can affect power systems with possible widespread voltage control problems, and some protective systems will mistakenly trip out key assets from the grid. Spacecraft operations may experience surface charging and tracking problems, which may require corrections for orientation problems. Other systems affected include satellite navigation, which may be degraded for hours, and low-frequency radio navigation can also be disrupted."

OK. That sounds like a bad thing. Back to NASA:

But the breach itself is not the biggest surprise. Researchers are even more amazed at the strange and unexpected way it forms, overturning long-held ideas of space physics.

"At first I didn't believe it," says THEMIS project scientist David Sibeck of the Goddard Space Flight Center. "This finding fundamentally alters our understanding of the solar wind-magnetosphere interaction."

The magnetosphere is a bubble of magnetism that surrounds Earth and protects us from solar wind.

The big discovery came on June 3, 2007, when the five probes serendipitously flew through the breach just as it was opening. Onboard sensors recorded a torrent of solar wind particles streaming into the magnetosphere, signaling an event of unexpected size and importance.

"The opening was huge—four times wider than Earth itself," says Wenhui Li, a space physicist at the University of New Hampshire who has been analyzing the data.

The event began with little warning when a gentle gust of solar wind delivered a bundle of magnetic fields from the Sun to Earth. Like an octopus wrapping its tentacles around a big clam, solar magnetic fields draped themselves around the magnetosphere and cracked it open. The cracking was accomplished by means of a process called "magnetic reconnection." High above Earth's poles, solar and terrestrial magnetic fields linked up (reconnected) to form conduits for solar wind. Conduits over the Arctic and Antarctic quickly expanded; within minutes they overlapped over Earth's equator to create the biggest magnetic breach ever recorded by Earth-orbiting spacecraft.

I understand octopus tentacles around a big clam. It's the part about north-pointing and south-pointing magnetic fields, later in the article, that started to lose me. But they summed things up pretty well.

The years ahead could be especially lively.

Is "lively" meant in the same way that Mel Gibson's character, Lt. Col. Moore, in We Were Soldiers said things were getting "sporty" when they were being all shot to heck?

Raeder explains: "We're entering Solar Cycle 24. For reasons not fully understood, CMEs in even-numbered solar cycles (like 24) tend to hit Earth with a leading edge that is magnetized north. Such a CME should open a breach and load the magnetosphere with plasma just before the storm gets underway. It's the perfect sequence for a really big event."

Sibeck agrees. "This could result in stronger geomagnetic storms than we have seen in many years."

Oh, great. For some reason, though, the NASA types don't seem to be alarmed by this. They're such geeks, getting excited about all the new things they're learning, when these geomagnetic storms risk affecting the power grid and satellite systems.

The good news from this discovery is that we can probably expect more appearances of the Northern Lights.

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