Nexus - 1205 - New Times Magazine-pages

Page Content (OCR)

NEWSCIENCENEWSCIENCENEWSCIENCE DOES THE EARTH HAVE A SOLAR UMBILICAL CORD? lanuary 2005 was a stormy month—in space. With little warning, a giant spot A common mistake made by critics of materialised on the Sun and started exploding. Between 15 and 19 January, | the electric model is to assume that the sunspot 720 produced four powerful solar flares. When it exploded a fifth time on | radial electric field of the Sun should be 20 January, onlookers were not surprised. not only measurable but also strong enough They should have been. Researchers realise now that the 20 January blast was | to accelerate electrons toward the Sun at something special. It has shaken the foundations of space weather theory and pos- |) "relativistic" speeds (up to 300,000 kilome- sibly changed the way astronauts are going to operate when they return to the) tres per second). By this argument, we Moon. should find electrons not only zipping past Scant minutes after the 20 January flare, a swarm of high-speed protons) our instruments but also creating dramatic surrounded Earth and the Moon. Thirty minutes later, the most intense proton storm | displays in the Earth's night sky. in decades was underway. But as noted above, in the plasma glow "We've been hit by strong proton storms before, but [never so quickly]," says solar | discharge model the interplanetary electric physicist Robert Lin of UC Berkeley. "Proton storms normally develop hours or | field will be extremely weak. No instru- even days after a flare." ment placed in space could measure the This one began in minutes. radial voltage differential across a few tens Proton storms cause all kinds of problems. They interfere with ham radio com-| of metres, any more than it could measure munications. They zap satellites, causing short circuits and computer reboots. | the solar wind acceleration over a few tens Worst of all, they can penetrate the skin of spacesuits and make astronauts feel sick. of metres. "An astronaut on the Moon, caught outdoors on January 20, would have had But we can observe the solar wind accel- almost no time to dash for shelter," says Lin. The storm came fast and "hard", with eration over tens of millions of kilometres, proton energies exceeding 100 million electron volts. These are the kind of high- confirming that the electric field of the energy particles that can do damage to human cells and tissue. Sun, though imperceptible in terms of volts "The last time we saw a storm like this was in February 1956." The details of that] per metre, is sufficient to sustain a power- event are uncertain, though, because it happened before the Space Age. "There| ful drift current across interplanetary space. were no satellites watching the Sun." Given the massive volume of this space, According to space weather theory (soon to be revised), this is how aproton) the implied current is quite sufficient to storm develops. It begins with an explosion, usually above a sunspot. Sunspots are power the Sun. places where strong magnetic fields poke through the surface of the Sun. For rea- sons no one completely understands, these fields can become unstable and explode, unleashing as much energy as 10 billion hydrogen bombs. From Earth we see a flash of light and X-rays. This is the "solar flare", and it's the first sign that an explosion has occurred. Light from the flare reaches Earth in only eight minutes. Next, if the explosion is powerful enough, a billion-ton cloud of gas billows away | [Note: This article, dated 27 April 2005, is from the blast site. This is the coronal mass ejection (CME). CMEs are relatively | copyright © 2005 Thunderbolts.info. The slow. Even the fastest ones, travelling at 1,000 to 2,000 km/s, take a day or so to) full text of this article, with text links, can reach Earth. You know a CME has just arrived when you see auroras in the sky. be viewed at http:/www.thunderbolts.info/ En route to Earth, CMEs plough through a lot of gaseous material, first in the Sun's | tpod/2005/ arch05/050427sun.htm.] atmosphere and then out in interplanetary space. You thought space was empty? No. The void between planets is filled with protons and other particles from the | Additional Reading solar wind. Shock waves in front of the CME can accelerate these protons in our) See also these Pictures of the Day: Look for more details on the drift cur- rent, solar magnetic fields, nuclear reac- tions and many other features of the Sun in upcoming Pictures of the Day at http://www.thunderbolts.info. oo direction—hence the proton storm. * Arc Lamp in the Sky "CMEs can account for most proton storms," says Lin, but not the proton storm of | _http://www.thunderbolts.info/tpod/2004/arch/ 20 January. 040729solar.htm According to theory, CMEs can't push material to Earth quickly enough. So, back | ° Stellar Nurseries to the drawing board. But if a CME didn't accelerate the protons, what did? http://www.thunderbolts.info/tpod/2004/arch/ "We have an important clue," says Lin. When the explosion occurred, sunspot | _040727stellar-nurseries.htm 720 was located at a special place on the Sun: 60 degrees west longitude. This| * Electric Stars _ means "the sunspot was magnetically connected to Earth". http://www thunderbolts.info/tpod/2004/arch/ He explains that the Sun's magnetic field spirals out into the solar system like | 040922electric-stars.htm water from a lawn sprinkler. (Why? The Sun spins like a lawn sprinkler does.) The] ° _ Tron Sun _ ’ magnetic field emerging from solar longitude 60 degrees W bends around and inter- Mae: hunderbo ts.info/tpod/2004/arch/ sects Earth. Protons are guided by magnetic force fields, so on 20 January there was | | Solar Tornadoes. a superhighway for protons leading all the way from sunspot 720 to our planet. attp://www.thunderbolts.info/tpod/2004/arch/ ‘That's how the protons got here, speculates Lin. 041015solar-tornado.htm How they were accelerated, however, remains a mystery. . . . ¢ Kepler Supernova Remnant (Source: NASA, 10 June 2005, http://science.nasa.gov/headlines/y2005/10jun_ http://www.thunderbolts.info/tpod/2004/arch/ newstorm.htm) 041103supernova.htm A common mistake made by critics of the electric model is to assume that the radial electric field of the Sun should be not only measurable but also strong enough to accelerate electrons toward the Sun at "relativistic" speeds (up to 300,000 kilome- tres per second). By this argument, we should find electrons not only zipping past our instruments but also creating dramatic displays in the Earth's night sky. But as noted above, in the plasma glow discharge model the interplanetary electric field will be extremely weak. No instru- ment placed in space could measure the radial voltage differential across a few tens of metres, any more than it could measure the solar wind acceleration over a few tens of metres. But we can observe the solar wind accel- eration over tens of millions of kilometres, confirming that the electric field of the Sun, though imperceptible in terms of volts per metre, is sufficient to sustain a power- ful drift current across interplanetary space. Given the massive volume of this space, the implied current is quite sufficient to power the Sun. Look for more details on the drift cur- rent, solar magnetic fields, nuclear reac- tions and many other features of the Sun in upcoming Pictures of the Day at http://www.thunderbolts.info. oo Additional Reading See also these Pictures of the Day: « Arc Lamp in the Sky http://www.thunderbolts.info/tpod/2004/arch/ 040729solar.htm ¢ Stellar Nurseries http://www.thunderbolts.info/tpod/2004/arch/ 040727stellar-nurseries.htm ¢ Electric Stars http://www.thunderbolts.info/tpod/2004/arch/ 040922electric-stars.htm * The Iron Sun http://www.thunderbolts.info/tpod/2004/arch/ 041006iron-sun.htm ¢ Solar Tornadoes http://www.thunderbolts.info/tpod/2004/arch/ 041015solar-tornado.htm ¢ Kepler Supernova Remnant http://www.thunderbolts.info/tpod/2004/arch/ 041 103supernova.htm 48 = NEXUS www.nexusmagazine.com AUGUST - SEPTEMBER 2005