The Moon and the Magnetotail

 Behold the full moon. Ancient craters and frozen lava seas lie motionless under an airless sky of profound quiet. It’s a serene, slow-motion world where even a human footprint may last millions of years. Nothing ever seems to happen there, right?

Wrong.

NASA-supported scientists have realized that something happens every month when the moon gets a lashing from Earth’s magnetic tail.

“Earth’s magnetotail extends well beyond the orbit of the moon and, once a month, the moon orbits through it,” says Tim Stubbs, a University of Maryland scientist working at the Goddard Space Flight Center. “This can have consequences ranging from lunar ‘dust storms’ to electrostatic discharges.”

Yes, Earth does have a magnetic tail. It is an extension of the same familiar magnetic field we experience when using a Boy Scout compass to find our way around Earth’s surface. Our entire planet is enveloped in a bubble of magnetism, which springs from a molten dynamo in Earth’s core. Out in space, the solar wind presses against this bubble and stretches it, creating a long “magnetotail” in the downwind direction.

Anyone can tell when the moon is inside the magnetotail. Just look: “If the moon is full, it is inside the magnetotail,” says Stubbs. “The moon enters the magnetotail three days before it is full and takes about six days to cross and exit on the other side.”

It is during those six days that strange things can happen.

Fine particles of dust on the moon’s surface can actually float off the ground when they become charged by electrons in Earth’s magnetotail. Credit: Tim Stubbs/University of Maryland/GSFC
> Larger image During the crossing, the moon comes in contact with a gigantic “plasma sheet” of hot charged particles trapped in the tail. The lightest and most mobile of these particles, electrons, pepper the moon’s surface and give the moon a negative charge.

On the moon’s dayside this effect is counteracted to a degree by sunlight: UV photons knock electrons back off the surface, keeping the build-up of charge at relatively low levels. But on the nightside, in the cold lunar dark, electrons accumulate and surface voltages can climb to hundreds or thousands of volts.

Imagine what it feels like to be a sock pulled crackling from a dryer. Astronauts on the moon during a magnetotail crossing might be able to tell you. Walking across the dusty charged-up lunar terrain, the astronauts themselves would gather a load of excess charge. Touching another astronaut, a doorknob, a piece of sensitive electronics — any of these simple actions could produce an unwelcome discharge. “Proper grounding is strongly recommended,” says Stubbs.

Earth’s magnetic field responds to the solar wind much like an airport wind sock: It stretches out with its tail pointing downwind. Credit: NASA/Goddard Space Flight Center- Conceptual Image Lab
> Magnetospheric substorm animation The ground, meanwhile, might leap into the sky. There’s growing evidence that fine particles of moondust might actually float, ejected from the lunar surface by electrostatic repulsion. This could create a temporary nighttime atmosphere of dust ready to blacken spacesuits, clog machinery, scratch faceplates (moondust is very abrasive) and generally make life difficult for astronauts.

Stranger still, moondust might gather itself into a sort of diaphanous wind. Drawn by differences in global charge accumulation, floating dust would naturally fly from the strongly-negative nightside to the weakly-negative dayside. This “dust storm” effect would be strongest at the moon’s terminator, the dividing line between day and night.

Much of this is pure speculation, Stubbs cautions. No one can say for sure what happens on the moon when the magnetotail hits, because no one has been there at the crucial time. “Apollo astronauts never landed on a full moon and they never experienced the magnetotail.”

The best direct evidence comes from NASA’s Lunar Prospector spacecraft, which orbited the moon in 1998-99 and monitored many magnetotail crossings. During some crossings, the spacecraft sensed big changes in the lunar nightside voltage, jumping “typically from -200 V to -1000 V,” says Jasper Halekas of UC Berkeley who has been studying the decade-old data.

The moon spends about six days each month inside Earth’s magnetic tail, or “magnetotail.” Credit: NASA/Steele Hill
> Larger image “It is important to note,” says Halekas, “that the plasma sheet (where all the electrons come from) is a very dynamic structure. The plasma sheet is in a constant state of motion, flapping up and down all the time. So as the moon orbits through the magnetotail, the plasma sheet can sweep across it many times. Depending on how dynamic things are, we can encounter the plasma sheet many times during a single pass through the magnetotail with encounters lasting anywhere from minutes to hours or even days.”

“As a result, you can imagine how dynamic the charging environment on the moon is. The moon can be just sitting there in a quiet region of the magnetotail and then suddenly all this hot plasma goes sweeping by causing the nightside potential to spike to a kilovolt. Then it drops back again just as quickly.”

The roller coaster of charge would be at its most dizzying during solar and geomagnetic storms. “That is a very dynamic time for the plasma sheet and we need to study what happens then,” he says.

What happens then? Next-generation astronauts are going to find out. NASA is returning to the moon in the decades ahead and plans to establish an outpost for long-term lunar exploration. It turns out they’ll be exploring the magnetotail, too.

More Information:

Earth’s magnetotail isn’t the only source of plasma to charge the moon. Solar wind can provide charged particles, too; indeed, most of the time, the solar wind is the primary source. But when the moon enters the magnetotail, the solar wind is pushed back and the plasma sheet takes over. The plasma sheet is about 10 times hotter than the solar wind and that gives it more “punch” when it comes to altering the charge balance of the moon’s surface. Two million degree electrons in the plasma sheet race around like crazy and many of them hit the moon’s surface. Solar wind electrons are relatively cool at only 140 thousand degrees, and fewer of them zip all the way down to the shadowed surface of the moon’s nightside.

YOUR KID IS STUPID

Saturn’s Titan: A Mirror Image of Earth Before Life Evolved?

The Cassini spacecraft observations of Saturn’s largest moon, the orange-colored Titan, have given scientists a glimpse of what Earth might have been like before life evolved. They now believe Titan possesses many parallels to Earth, including lakes, rivers, channels, dunes, rain, snow, clouds, mountains and possibly volcanoes.

“Titan is just covered in carbon-bearing material — it’s a giant factory of organic chemicals,” according to Ralph Lorenz of Johns Hopkins University Applied Physics Laboratory. “We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe.”

“When we designed the original tour for the Cassini spacecraft, we really did not know what we would find, especially at Enceladus and Titan,” said Dennis Matson, the JPL Cassini project scientist. “This extended tour is responding to these new discoveries and giving us a chance to look for more.”

Unlike Earth, Titan’s lakes, rivers and rain are composed of methane and ethane, and temperatures reach a chilly minus 180 degrees Celsius (minus 290 degrees Fahrenheit). Although Titan’s dense atmosphere limits viewing the surface, Cassini’s high-resolution radar coverage and imaging by the infrared spectrometer have given scientists a better look.

Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to new data from NASA’s Cassini spacecraft. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes.

At an eye popping minus 179 degrees Celsius (minus 290 degrees Fahrenheit), Titan has a surface of liquid hydrocarbons in the form of methane and ethane with tholins believed to make up its dunes. The term “tholins,” coined by Carl Sagan in 1979, describe the complex organic molecules at the heart of prebiotic chemistry.

Cassini has mapped about 20 percent of Titan’s surface with radar. Several hundred lakes and seas have been observed, with each of several dozen estimated to contain more hydrocarbon liquid than Earth’s oil and gas reserves. Dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth’s coal reserves.

Proven reserves of natural gas on Earth total 130 billion tons, enough to provide 300 times the amount of energy the entire United States uses annually for residential heating, cooling and lighting. Dozens of Titan’s lakes individually have the equivalent of at least this much energy in the form of methane and ethane.

“This global estimate is based mostly on views of the lakes in the northern polar regions. We have assumed the south might be similar, but we really don’t yet know how much liquid is there,” said Lorenz. Cassini’s radar has observed the south polar region only once, and only two small lakes were visible. Future observations of that area are planned during Cassini’s proposed extended mission.

“We also know that some lakes are more than 10 meters or so deep because they appear literally pitch-black to the radar. If they were shallow we’d see the bottom, and we don’t,” said Lorenz.

The question of how much liquid is on the surface is an important one because methane is a strong greenhouse gas on Titan as well as on Earth, but there is much more of it on Titan. If all the observed liquid on Titan is methane, it would only last a few million years, because as methane escapes into Titan’s atmosphere, it breaks down and escapes into space. If the methane were to run out, Titan could become much colder. Scientists believe that methane might be supplied to the atmosphere by venting from the interior in cryovolcanic eruptions. If so, the amount of methane, and the temperature on Titan, may have fluctuated dramatically in Titan’s past.

Cassini’s mission originally had been scheduled to end in July 2008. A newly-announced two-year extension will include 60 additional orbits of Saturn and more flybys of its exotic moons. These will include 26 flybys of Titan, seven of Enceladus, and one each of Dione, Rhea and Helene. The extension also includes studies of Saturn’s rings, its complex magnetosphere, and the planet itself.

“This extension is not only exciting for the science community, but for the world to continue to share in unlocking Saturn’s secrets,” said Jim Green, director, Planetary Science Division, NASA Headquarters, Washington. “New discoveries are the hallmarks of its success, along with the breathtaking images beamed back to Earth that are simply mesmerizing.”

Based on findings from Cassini, scientists think liquid water may be just beneath the surface of Saturn’s moon Enceladus. The small moon, only one-tenth the size of Titan and one-seventh the size of Earth’s moon, is one of the highest-priority targets for the extended mission.

Cassini discovered geysers of water-ice jetting from the Enceladus surface. The geysers, which shoot out at a distance three times the diameter of Enceladus, feed particles into Saturn’s most expansive ring. In the extended mission, the spacecraft may come as close as 25 kilometers (15 miles) from the moon’s surface.

Other activities for Cassini scientists will include monitoring seasons on Titan and Saturn, observing unique ring events, such as the 2009 equinox when the sun will be in the plane of the rings, and exploring new places within Saturn’s magnetosphere.

Cassini has returned a daily stream of data from Saturn’s system for almost four years. Its travel scrapbook includes nearly 140,000 images, and information gathered during 62 revolutions around Saturn, 43 flybys of Titan and 12 close flybys of the icy moons.

More than 10 years after launch and almost four years after entering into orbit around Saturn, Cassini is a healthy and robust spacecraft. Three of its science instruments have minor ailments, but the impact on science-gathering is minimal. The spacecraft will have enough propellant left after the extended mission to potentially allow a third phase of operations. Data from the extended mission could lay the groundwork for possible new missions to Titan and Enceladus.

Cassini launched Oct. 15, 1997, from Cape Canaveral, Fla., on a seven-year journey to Saturn, traversing 3.5 billion kilometers (2.2 billion miles).

World Population to Hit 6,666,666,666 in May

To many people, this means nothing. But of course 666 refers to the Beast in the Bible. Heaven knows what ten sixes means.

I don’t know who first noticed this looming numerical curiosity, but it was mentioned today on the Drudge report. To see the projection, go to the U.S. Census Bureau’s World POPClock Projection page. There you’ll find these projections among others:

05/01/08 6,664,737,085
06/01/08 6,671,275,141

So sometime in between May 1 and June 1, the gaggle-of-sixes milestone will be passed. (I say gaggle rather than googol, which is a 1 followed by 100 zeros. I could also have used a gazillion or a jillion or a bazillion, all of which are just figures of speech meaning “a lot.” Clearly, the number of people on Earth is a lot more than umpteen.)

The Census Bureau of course never knows exactly how many people are on the planet, or even in the United States for that matter. It’s all estimates. Just fun.

The last big “six scare” was 06/06/06 (June 6, 2006). We survived that, so I imagine we’ll get through this one.

(For the record, 07/07/07 came and went last year without any documented cases of extreme luck directly attributed to the date, and coming up later this year: 08/08/08.)

Vitamin supplements may increase risk of death

Vitamin supplements taken by millions of people do not increase life expectancy and may raise the risk of a premature death , according to a review of 67 studies with more than 230,000 subjects.

The review, by the Cochrane Collaboration which regularly pools data from trials to evaluate drugs and treatments, found supplements vitamin A, vitamin E and beta-carotene are detrimental to health. In 47 trials with 180,938 people and a low risk of bias, the “antioxidant supplements significantly increased mortality”, the authors wrote. When the antioxidants were assessed separately and low risk of bias trials were included and selenium excluded, vitamin A was linked to a 16% increased risk of dying, beta-carotene to a 7% increased risk and vitamin E to a 4% increased risk.

Evidence for vitamin C and selenium was more equivocal, suggesting there was no benefit to taking these pills compared with a placebo.

“The bottom line is current evidence does not support the use of antioxidant supplements in the general healthy population or in patients with certain diseases,” said Goran Bjelakovic, who performed the review at Copenhagen Universityhospital in Denmark. “There was no indication that vitamin C and selenium may have positive or negative effects. So regarding these we need more data from randomised trials.”

All the supplements are categorised as antioxidants; research has suggested these chemicals underlie some of the beneficial effects of eating fruit and vegetables because they soak up harmful byproducts of metabolism which can damage cells and cause aging.

While the evidence of a beneficial effect of a diet rich in fruit and veg is solid, the Cochrane data suggest antioxidant supplements are either useless or detrimental.

Bjelakovic’s team evaluated 67 randomised clinical trials with 232,550 subjects; 21 of the trials were on healthy subjects, while the rest tested patients with a range of diseases. The evidence suggests it would be safer to obtain the chemicals not as supplements but by eating plenty of fruit and vegetables.

Top 10 Banned Films of the 20th Century

#10 – THE OUTLAW [1943]

 

Notable for bringing sex to the Western genre, Howard Hughes’ The Outlaw was shelved for years before finally receiving approval by the Hollywood Production Code Administration. The whole controversial production seems to have gone forward for one reason: To showcase actress Jane Russell’s magnificent breasts. The film’s slogan was “What are the two biggest reasons for Jane Russell’s success?” During filming, Hughes once commented, “We’re not getting enough production from Jane’s breasts.” In her memorable screen debut, Russell portrayed “Rio McDonald.” Oh yeah, The Outlaw also starrred Walter Huston (The Treasure of the Sierra Madre), Thomas Mitchell (It’s a Wonderful Life) and Jack Buetel as “Billy the Kid.”

 

 

#09 – ALL QUIET ON THE WESTERN FRONT [1930]

Directed by Lewis Milestone, All Quiet on the Western Front was based on the critically acclaimed Erich Maria Remarque novel, Im Westen nichts Neues, and starred Lew Ayres as the disillusioned soldier, Paul Baumer. The film, which won an Academy Award for Best Picture, was eventually banned in Germany due to its anti-war theme: “You still think it’s beautiful to die for your country. The first bombardment taught us better. When it comes to dying for country, it’s better not to die at all.” However, during the film’s brief run in Germany, the Nazis released rats into the theaters to scare off movie patrons. All Quiet on the Western Front was also banned in Italy until 1956.

 

 

#08 – I AM CURIOUS (YELLOW) [1967]

 

Banned in Massachusetts for being pornographic, this notorious Swedish film (Jag är nyfiken – gul) faced a landmark court battle in the United States and was eventually found to be not obscene by the United States Court of Appeals. Directed by Vilgot Sjöman, the film starred Lena Nyman and is a companion film to I Am Curious (Blue) (1968). The films were named after the colors of the Swedish flag. I Am Curious (Yellow) contains documentary elements, including an interview with Martin Luther King, Jr.

 

 

#07 – THE BIRTH OF A NATION [1915]

 

Based on Thomas Dixon’s novel, The Clansman, D. W. Griffith’s controversial and extremely influential silent film classic caused riots in Boston, Philadelphia and other major cities. The NAACP organized protests at the various premieres of the film around the country. In addition, The Birth of a Nation was outright banned in several cities such as Chicago, Pittsburgh and Kansas City due to its racist themes. U.S. President Woodrow Wilson commented that the movie, which starred Lillian Gish and Mae Marsh, was “like writing history with lightning.” Griffith’s next silent film masterpiece, Intolerance, was made in reaction to the negative response he received from The Birth of a Nation.

 

 

#06 – THE TIN DRUM [1979]

 

“A savage, sweeping epic of society in chaos.” Adapted from the critically acclaimed novel (Die Blechtrommel) by Günter Grass, The Tin Drum won the Academy Award for Best Foreign Language Film and the Palme d’Or at the Cannes Film Festival. However, the film was banned in several countries, including parts of Canada, as well as in Oklahoma City for a short time, due to a controversial scene that appears to show minors engaging in oral sex.

 

 

#05 – HAIL MARY [1985]

 

In Hail Mary (Je vous salue, Marie), the Virgin Mary is a gas station attendant whose boyfriend, Joseph, drives a taxi. Even Pope John Paul II jumped into the battle over this controversial, modern retelling of the virgin birth story from Jean-Luc Godard, claiming that the film “deeply wounds the religious sentiments of believers.”

 

 

#04 – LAST TANGO IN PARIS [1973]

 

Directed by Bernardo Bertolucci, Last Tango in Paris (Ultimo tango a Parigi) details the bizarre relationship of an American widower (Marlon Brando) and a young Parisian woman (Maria Schneider). The film caused much controversy for the so-called “butter scene,” which is extremely tame by today’s standards. Schneider, who claims she is still haunted by the scene, was quoted in the New York Post (July 23, 2007), claiming that the scene wasn’t part of the original script: “The truth is it was Marlon who came up with the idea . . . I should have called my agent or had my lawyer come to the set because you can’t force someone to do something that isn’t in the script . . . I was crying real tears. I felt humiliated and, to be honest, I felt a little raped . . . Thankfully, there was just one take . . . I never use butter to cook anymore – only olive oil.” According to a court in Bologna that banned the film: “Obscene content offensive to public decency . . . presented with obsessive self-indulgence, catering to the lowest instincts of the libido, dominated by the idea of stirring unchecked appetites for sexual pleasure, permeated by scurrilous language . . . accompanied off screen by sounds, sighs and shrieks of climax pleasure.”

 

 

#03 – THE LAST TEMPTATION OF CHRIST [1988]

“I am here to set fire to the world!” Martin Scorsese directed this adaption of Nikos Kazantzakis’ controversial 1953 novel that is notable for the scandal it caused as well as for its bizarre casting that included Willem Dafoe as Jesus, Barbara Hershey as Mary Magdalene, Harvey Keitel as Judas Iscariot, David Bowie as Pontius Pilate and Harry Dean Stanton as Paul. Numerous religious leaders throughout the United States organized protests against The Last Temptation of Christ (many of whom didn’t bother to make an effort to watch the film!) and several Southern cities such as Savannah, Georgia, banned the film. In addition, Blockbuster Video initially refused to carry the title in its stores. Scorsese was nominated for an Academy Award for Best Director for his efforts (Barry Levinson ended up winning the award for Rain Man).

 

 

#02 – TITICUT FOLLIES [1967]

 

“Don’t turn your back on this film . . . if you value your mind or your life.” A fascinating (and extremely disturbing!) black and white documentary dealing with the mistreatment of patients at the Massachusetts Correctional Institution, a prison hospital for the criminally insane, Titicut Follies was banned in the United States after a ruling by the Massachusetts Supreme Judicial Court determined that the film violated the patients’ right to privacy. However, many critics believed that the film was removed from circulation by the Commonwealth of Massachusetts to protect its own reputation. Finally, in 1992, the film aired on PBS and is now widely available.

 

 

#01 – CANNIBAL HOLOCAUST [1980]

 

“Oh, good Lord! It’s unbelievable. It’s horrible. I can’t understand the reason for such cruelty!” Directed by Italian filmmaker Ruggero Deodato and filmed in the Amazon Rainforest, Cannibal Holocaust was banned in many countries upon its initial release due to its graphic gore and sexual violence, as well as for several gruesome (and genuine!) animal slayings that appear in the film. Rumors also circulated that it was a snuff film (which at least proved to be untrue!). Countries that banned the movie at one time or another include Italy, New Zealand, Australia, Malaysia, Burma, Norway, South Africa, Finland, Turkey, Singapore, Germany, Iran and Morocco. Believe it or not, Cannibal Holocaust remains banned in several countries to this day . . . “Man is omnipotent; nothing is impossible for him. What seemed like unthinkable undertakings yesterday are history today. The conquest of the moon for example: who really talks about it anymore? Today we are already on the threshold of conquering our galaxy, and in a not too distant tomorrow, we’ll be considering the conquest of the universe, and yet man seems to ignore the fact that on this very planet there are still people living in the stone age and practicing cannibalism.”