Geek Trivia: Circuit of the stars

by Jay Garmon | Oct 24, 2006 8:12:00 PM

Tags: Jay Garmon, direct current, voltage, Geek Trivia Newsletter

Takeaway: What is the largest DC electrical circuit in the solar system?

There's a rule of thumb in electrical engineering that dates back to the heady days of technological rivalry between Nikola Tesla and Thomas Edison: Alternating current (AC) is more efficient and easier to transmit over practical distances than direct current (DC). By and large, this is true, but that doesn't mean DC doesn't have its uses�in fact, DC transmission may be on the cusp of a large-scale comeback.

The "problem" with DC is that it loses voltage over long transmission distances, and it's comparatively difficult to transform DC voltages. AC, by contrast, is more efficient over long distances and more easily transformed for various commercial and consumer uses.

However, if you're designing and operating an entirely closed electrical system, with no plans to tap the lines for houses or shops or pirate radio towers along the way, then DC might just be what you're looking for�especially if you're dealing in very high voltages.

High-voltage direct current (HVDC) transmission can transfer bulk power between electrical generating stations, even over long distances. In these cases, there are no taps on the DC line between point A and point B, so the transformation issue is moot.

That leaves the voltage drop problem. With DC, voltage drops decrease exponentially when you increase the initial voltage. Put another way, if you're using really high voltage to start with�far higher than any consumer would ever need�then DC becomes an efficient transmission system.

Some of the most notable uses of HVDC power lines are in extreme environments. One such example is the Arctic Circle, where Russian and Canadian power lines run DC power over both long, sparsely inhabited distances and underwater. And it's the latter that may lead to an HVDC upswing.

Many consider wind power to be a promising alternative power source, and many engineers are designing wind turbines to install off-shore, just beyond the horizon�where their visibility won't "blight" beachfront real estate. Undersea HVDC cables may be the preferred choice for tapping these turbines, which could represent some of the largest and most powerful DC circuits on earth.

Still, no new technology is likely to surpass the biggest and most powerful DC circuit in the solar system.

WHAT IS THE LARGEST DC ELECTRICAL CIRCUIT IN THE SOLAR SYSTEM?

What's the biggest, most powerful DC circuit in the solar system�a mind-boggling phenomenon that dwarfs even the longest and high-voltage direct current (HVDC) systems on Earth?

It turns out that the biggest planet in the local astrophysical neighborhood is also the biggest electrical generator. Jupiter runs a two-trillion-watt DC electrical circuit between its metallic hydrogen clouds and its hyper-volcanic moon, Io. The field lines of Jupiter's magnificently massive magnetosphere carry this unparalleled current.

Judged by raw volume, Jupiter's magnetosphere is the largest celestial phenomenon in our solar system. Larger than the sun itself, the Jovian magnetosphere reaches all the way to Saturn. If it were visible to the naked eye, it would appear larger than the full moon when viewed from Earth.

Within this incredible magnetic field orbits Io, the most volcanic body known to man. Io is constantly ejecting sulfur dioxide into space, creating an SO₂ cloud that hangs within Io's orbit. Ionized within the grip of Jupiter's magnetosphere, the sulfur dioxide atoms create a donut-shaped body known as the Io Plasma Torus.

As Io itself moves within this torus, it effectively acts like an electrical generator, much like moving a coiled wire over a magnet. The electrical potential built by this astronomic generator flows down to Jupiter, creating a DC circuit of unbelievable power.

Scientists don't entirely understand the physics behind the Io-Jupiter circuit, and they're constantly examining space probe and radio telescope data to unravel the mystery. However, the Io-Jupiter circuit isn't the only strange product of Jovian magnetosphere�Jupiter, it seems, is also quite the ham radio operator.

The interaction of ionized gases above Jupiter's magnetic poles creates a natural radio laser (or maser, if you prefer), which can produce more intense ham-radio-frequency noise than our sun. With just a reasonable amount of ham radio equipment, anyone can tune into Jupiter's trademark broadcasts, which sound like a combination of high-speed whistles, ocean waves, and woodpeckers working on a good solid tree.

NASA runs an educational project called Radio Jove that helps educators and enthusiasts tune in to Jupiter's audio show. That's not just fun science�it's electrifying Geek Trivia.

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The Quibble of the Week

If you uncover a questionable fact or debatable aspect of this week's Geek Trivia, just post it in the discussion area of the article. Every week, yours truly will choose the best post from the assembled masses and discuss it in the next edition of Geek Trivia.

This week's quibble comes from the October 4 edition of Geek Trivia, "Science-fiction double feature." TechRepublic member TomMerritt questioned my characterization of a certain Arthur C. Clarke novel.

". . . Wasn't Clarke's book 2001: A Space Odyssey an adaptation of the Clarke/Kubrick movie rather than the other way around?"

Well, a host of members chimed in to help clear up the issue. Member jsanderson added, "According to this Wikipedia article, [the novel] was 'developed concurrently with Stanley Kubrick's film version.'"

TechRepublic member J. D. S. quoted another Wikipedia article to explain further. "Clarke's short story, 'The Sentinel,' was 'expanded and. . . modified into the novel and movie.'"

All of which is to say, the movie 2001: A Space Odyssey wasn't a strict adaptation of the novel, which makes for some great trivia itself. Thanks for the info, and keep those quibbles coming.

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The Trivia Geek, also known as Jay Garmon, is a former advertising copywriter and Web developer who's duped TechRepublic into underwriting his affinity for movies, sci-fi, comic books, technology, and all things geekish or subcultural.

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