Wednesday, January 06, 2010

Happy Geek Year again!

Okay, this is kinda complicated so I'm not going to go into all the details. But it displays two of the things that I like about science.

Here's the deal: The solar system is now passing though an interstellar cloud known as the Local Interstellar Cloud or "Local Fluff" for short.
It's about 30 light years wide and contains a wispy mixture of hydrogen and helium atoms at a temperature of 6000 C.
The thing is, this cloud is surrounded by a giant bubble of interstellar gas at a million degrees, formed by supernova explosions - and the cloud should have either been crushed or dispersed by the higer-pressure surroundings.

In other words, according the the laws of physics, it shouldn't exist.

Science mysteries are way cool. Stuff that makes scientists scratch their heads are one of the best ways to new discoveries.

Well, they mystery has been solved by a pair of 32-year old spacecraft, Voyager 1 and Voyager 2, launched in September and August 1977, respectively. (That's not a typo: Voyager 2 was launched first. They were numbered the way they were because Voyager 1, by virtue of having a different trajectory, would pass the other craft and reach the original prime targets of the missions - Saturn and Jupiter - first.)

The solar system is enveloped in a bubble formed by the solar winds - charged particles flowing outward from the sun - called the heliosphere. The outermost layer of the heliosphere, where the solar winds are being slowed by the pressure of interstellar gas, is called the heliosheath. That is where Voyager 1 and 2, nearly 11 billion and 9 billion miles from Earth respectively (more than twice the distance to Pluto) are. Beyond the heliosheath is the Local Fluff. So the probes are
on the verge of entering interstellar space - but they are not there yet.

"The Voyagers are not actually inside the Local Fluff," says [Merav] Opher[, a NASA Heliophysics Guest Investigator]. "But they are getting close and can sense what the cloud is like as they approach it."
And what they have found is that
"the Fluff is much more strongly magnetized than anyone had previously suspected - between 4 and 5 microgauss," says Opher. "This magnetic field can provide the extra pressure required to resist destruction."
A gauss is a measure of the strength of a magnetic field; a microgauss is one millionth of a gauss. By comparison, the Earth's magnetic field is about 0.5 gauss, or 500,000 microgauss.

And that's the second thing I like about science shown here: Resolving those head-scratching conundrums with new discoveries and new understandings.

Solving puzzles leading to new learning. What's not to like?

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