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A tear in the magnetic field

The most recent "hole event", according to Dr. Marit Oieroset of the University of California at Berkeley lasted just an hour - however, what caught Oieroset and other scientists by surprise what that the hole expanded rapidly before it began to close. The myserious holes formed on the side of our magnetic shield facing the Sun.

According to Oieroset, within the hour the holes had opened and then closed, the amount of solar wind falling to the Earth's surface was 20 times higher than normal. Both tears in the magnetic field allowed the solar wind to reach Earth's atmosphere at speeds of over 1 million MPH!

"The discovery... could be used to predict when solar storms will be severe. Based on these results, we expect more severe storms during the upcoming solar cycle," said Vassilis Angelopoulos of the University of California, Los Angeles, principal investigator for THEMIS.

"Earth's magnetic field acts as a shield against the bombardment of particles continuously streaming from the Sun. Because the solar particles (ions and electrons) are electrically charged, they are affected by magnetic forces; most are deflected by our planet's magnetic field," according to a NASA news release "However, our magnetic field is a leaky shield and the number of particles breaching this shield depends on the orientation of the Sun's magnetic field. It had been thought that when the Sun's magnetic field is aligned with that of the Earth, the door is shut and that few if any solar particles enter Earth's magnetic shield."

NASA concluded: "The door was thought to open up when the solar magnetic field direction points opposite to Earth's field, leading to more solar particles inside the shield." Now, it appears, space researchers know better.

What's in the Sky: Winter got a chilly welcome reception Dec. 20, at 7:04 a.m. This time marked the winter solstice, the shortest day of the year. It's all up hill to spring (and longer days) from here.

Louis Varricchio, M.Sc., is a former NASA science writer. He is both a member of the NASA/JPL Solar System Ambassador program and a senior member of the U.S. Civil Air Patrol.

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