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The Universe

Dust in Space
It's downright dirty out there in the cosmos.

Space isn't empty. It's full of schmutz. As the Earth makes its annual journey around the sun, it collects about 40,000 tons (35,000 metric tons) of dust. Not to put too fine a point on it, but space is filthy.
Jets designed to spy on the former Soviet Union now scream through the stratosphere with the peaceful purpose of collecting tiny grains of cosmic dust. Scientists put the dust under the microscope and try to discern its message. They've collected so much that NASA has an online cosmic dust catalog (more evidence that you can find anything on the Internet).
Although hydrogen and helium are the most common elements found in space, the dust is made of heavier atoms born in the hearts of stars and supernovae: oxygen, nitrogen, iron, even a smattering of gold and uranium—pretty much the entire periodic table.

Dust isn't the only stuff sullying space. As many of us learned last fall, solar storms occasionally trigger a "coronal mass ejection," a spew of charged particles that can disrupt communications systems and intensify the northern lights. Even on a calm day, the sun emits a mighty solar wind, a stream of protons and heavy elements racing through space.
Despite all the stuff, not all parts of space are equally dirty. As you get outside the solar system, into interstellar space, particles become few and far between. In fact, our solar system is traveling through an area of relatively empty space right now. The current theory is that a supernova cleared out the region millions of years ago. The signature of that explosion (or maybe there was more than one) would be extremely hot, fast-moving particles, the equivalent of embers from an ancient fire.
A new space probe called the Cosmic Hot Interstellar Plasma Spectrometer, or CHIPS, is looking for signs of those embers in what scientists call the local hot bubble, but so far has only found traces of them. The local hot bubble doesn't seem to be that hot, and the emptiness can't yet be explained. But CHIPS will keep looking.
The way things are arranged gives us clues to our galactic past. "It's like archaeology," says Mark Hurwitz, principal CHIPS investigator. "The galaxy is not in perfect equilibrium. It's constantly percolating, stirred up by supernovae."
Even if our local bubble turns out to be as hot as we think it should be, and as clean (by the scuzzy standards of outer space), it wouldn't be the empty void—the vacuum—that we were brought up to believe in. If you could extract everything from space, all the dust, the zooming intergalactic particles, all the photons from impossibly distant stars, you still wouldn't be left with pure nothingness. Quantum physics tells us that the "vacuum" is shot through with virtual particles winking in and out of existence all the time.

In this universe, void is prohibited.

—Joel Achenbach
    Washington Post staff writer

Web Links

Stardust: NASA's Comet Sample Return Mission
The Stardust spacecraft was launched in 1999 with the mission to collect interplanetary dust particles, in particular those from comet Wild II, which it recently encountered in early January 2004.  Stardust has now begun its return to Earth and is due to touch down in 2006.  This website logs the history of the mission and has links to newsletters, team biographies, and press releases.

NASA Solar Physics
Put together by the Science Directorate of the Marshall Space Flight Center, this treasure trove of information contains an overview of solar physics, with sections on topics such as solar structure, solar features (including solar wind), and the sun in action, as well as recent news stories and past, current, and future projects of the center.

CHIPS: Cosmic Hot Interstellar Plasma Spectrometer
The opening sentence in the overview section, "Diffuse million-degree plasma is ubiquitous in the Universe," proves this site is not for beginners.  For those conversant in astrophysics, though, it provides information on the local bubble (an interstellar region of low density and hot gas) and the CHIPS spectrograph, mission, and latest news.  Click on the education section for a less technical overview.

NASA Cosmic Dust Laboratories
Need a dust sample of your own?  Find out how to apply for one on this site of NASA's Johnson Space Center.  You'll also find Cosmic Dust Catalogs 15 and 17 and more detailed information on the available dust samples.

Montana State University Solar Physics Group
MSU's Coronal Mass Ejection Prediction Page of frequently asked questions will answer questions you didn't even know to ask about CMEs—ejections of a large amount of materials from the sun's outer atmosphere—including frequency, relation to sunspots, and affect on the Earth.

More Articles by Joel Achenbach
Read some of writer Joel Achenbach's columns for the Washington Post.

Free World Map

Testimony to the U.S. House of Representatives Committee on Science,
Subcommittee on Space and Aeronautics—a hearing on "Asteroids: Perils and Opportunities," (
May 21, 1998. 


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