Posted on 09/01/2003 9:20:40 AM PDT by blam
It's Raining Stardust: Spacecraft measures record amount of stellar debris
Ron Cowen
Intruder alert! Stardust is sneaking into our solar system at three times the rate that it was just 6 years ago. Moreover, the influx of dust could triple again by the end of 2010.
DUST COLLECTOR. Artist's view of the Ulysses spacecraft, which has flown over the sun's poles. European Space Agency
These findings are based on the latest measurements by the Ulysses spacecraft, launched in 1990 to become the first observatory to explore the sun's poles. Before Ulysses' tour, which takes it from Jupiter's neighborhood to far above the solar poles, most astronomers didn't think much dust from other stars could penetrate the solar system. Sunlight rapidly charges dust attempting to enter the solar system, and, according to conventional theory, the sun's magnetic field then ejects the particles.
But in 1993, the space probe found that some particles barrel through the sun's magnetic shield. During solar maximum, when activity on the sun is most intense, even more stardust penetrates. That's because the sun's magnetic field begins flipping polarity, and the disordered field can't efficiently deflect dust particles.
Yet even though solar maximum ended in 2001, the rate at which stardust enters the solar system has remained high, report Markus Landgraf of the European Space Agency in Darmstadt, Germany, and his colleagues in the October Journal of Geophysical Research.
The explanation lies in the gradual way that the magnetic field changes polarity, Landgraf says. The field is now pointing nearly sideways, with its north and south magnetic poles lying along the sun's equator. In this configuration, the direction of the magnetic field rotates along with the sun every 28 days. Because the dust takes several months to react to the magnetic field, it experiences an average magnetic force of nearly zero. As a result, the magnetic field is now ineffective as a gatekeeper.
When the magnetic field finishes the reversal it began in 2001, it will focus stardust into the plane in which the planets orbit rather than expel the material. Landgraf says that he expects that the rate at which stardust enters the solar system will increase through about 2010.
About 0.6 micrometer in diameter, the particles are several times larger, and hence more massive, than astronomers had predicted. Greater mass may help the dust particles infiltrate the solar system.
Although the particles are still too tiny to affect the planets, their abundance probably leads to more collisions with comets and asteroids than usual, says Landgraf. That would result in more asteroid and comet fragments being generated.
These findings bode well for the Stardust space probe, which is scheduled to bring samples of cometary and stardust particles to Earth in 2006. The increased amount of stardust and the particles' larger-than-expected size should make for greater, easier-to-detect samples, says Stardust investigator Donald E. Brownlee of the University of Washington in Seattle.
"People often think of dust as trivial, but it's a major character in the solar system and throughout the galaxy," he says. Not only does dust absorb starlight, reradiating it as heat, it ferries such elements as iron, carbon, and silicon into the solar system, Brownlee notes.
Studying stardust near our sun, adds Landgraf, offers clues to how other stars interact with their surroundings.
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But what is it in fractions of an inch?
Let me know if you wish to be added or removed from this list.
Thanks. After a thirty year career in chip-making, I've been retired for almost nine years and have lost touch.
1) Sun's ultraviolet radiation can charge objects.
2) According to James McCanney, the solar system has a electrical field gradiant due to the sun's proton wind, sun negative, spherical zone of positive charge beyond Pluto's orbit.
Either way, dust that enters the solar system picks up positive charge, and is potentially attracted to the sun, and baring any significant magnetic field around the sun, plunges in.
Could this explain the cosmic microwave background radiation? The starlight is absorbed and reradiated as heat? Seems quite a bit simpler than the current theories cosmologists cling to.
According to Eric Lerner, "The Big Bang Never Happened", the cosmic microwave background radiation is not an artifact of the big bang, but is a diffuse microwave fog generated, absorbed and re-radiated by spiraling electrons trapped in powerful magnetic fields spawned by vast plasmic currents running around the universe.
Lerner asserts that the big bang origin of the cosmic background radiation has many defects. Among the most glaring: at about 3-4 degrees, it's about 1/10th the predicted temperature; its spectrum is much too perfect and its appearance is too isotropic to account for the observed large structures in the universe.
Just that the circulation of certain elements in the atmosphere could cause a magnetic field. The mag field being due to earth's core is a hypothesis, and doesn't explain the sun's nor Jupiter's massive mag fields.
Not warming, cooling, according to this.
Galactic dust cooling Earth?
Nature ^ | 8 July 2003 | TOM CLARKE
Controversial climate claim exonerates carbon dioxide.
The impact of cosmic rays on our climate might outweigh that of the greenhouse gas carbon dioxide, a controversial new report suggests1.
"It's no excuse to ignore sensible resource use," says one of the report's authors, physicist Nir Shaviv of the Hebrew University of Jerusalem in Israel. "But the bottom line is that carbon dioxide is not the bad boy that people claim it is."
The suggestion has met with scepticism, however: "I don't buy it," says climate-change expert Wallace Broecker of Columbia University in New York.
Shaviv and climatologist Ján Veizer of Ruhr University, Germany, reckon that the spiral arms of our galaxy hold the secret to the Earth's see-sawing climate. Every 150 million years, blasts of cosmic rays cool the planet on its stately passage through the cosmos, they argue2.
Cosmic rays thrown out by dying stars in the dust-rich arms of the Milky Way increase the number of charged particles in our atmosphere. There is some evidence that these may encourage low-level clouds to form, which cool the Earth.
Shaviv and Veizer have created a mathematical model of the number of cosmic rays hitting our atmosphere. They compared its predictions with other researchers' estimates of global temperatures and carbon dioxide levels over the past 500 million years.
They conclude that cosmic rays alone can account for 75% of the change in global climate during that period, and that less than half of the global warming seen since the beginning of the twentieth century is due to greenhouse gases.
The links are tenuous, others counter. Palaeontologist Paul Olsen, also of Columbia University, warns that Shaviv's study shows only a correlation between temperature, as inferred from ancient sediment records, carbon dioxide, as inferred from fossilized sea shells and cosmic rays, as inferred from meteorites. All three techniques are open to interpretation. Plus, geologists consider one of the 'cool' periods in the mathematical reconstruction to be a warm period, Olsen points out.
Despite these uncertainties - which hamper many efforts to reconstruct past climate - some researchers are more receptive. "It's intriguing," says Giles Harrison of the University of Reading, UK, who studies cosmic rays' impact on climate.
Shaviv attempts to explain how the Sun's natural variability affects the number of cosmic rays hitting the Earth, says Harrison. The Sun also produces radiation similar to cosmic rays, especially at the hottest part - called the solar maximum - of its 11-year cycle. Previous studies have failed to tease apart the climatic impacts of this radiation, of cosmic rays from the galaxy, and of warmth from the Sun.
Upcoming research should help clarify the situation. Physicists plan to mimic cloud formation in the lab by using particle accelerators to create cosmic-ray-like radiation.
References:
1. Shaviv, N. J. & Veizer, J. Celestial driver of Phanerozoic climate? GSA Today, 13, 4 - 10, (2003).Homepage
2. Shaviv, N. J. Cosmic ray diffusion from the galactic spiral arms, iron meteorites, and a possible climatic connection? Physical Review Letters, 89, (2002).Article
The links all work.
Excellent. I made the break and never looked back.
:Keep your lectric eye on me Babe,
Put your raygun to my head,
Press your space-face close to mine love,
freak out in a moonage daydream, Oh yeah...”
The only tune I have on my cell phone.
I’ve been listening to Bowie since literally Space Oddity hit the airwaves.
I don’t give a crap if he is as queer as a three dollar bill.
The man is a rock and roll genius. A brilliant writer and composer, an arranger par excellence.
I went to the very first ever concert at the Tacoma dome with a beautiful Irish Catholic gal named Cathy who I wish to this day I had been able to convince to marry me. I did everything but get on my knees...
August 11th, 1983
Still love Bowie.
Goes without saying I will love her forever...
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