Tearing into each other: When the magnetic fields of the Sun and Earth align, Earth's protective bubble can be breached, letting in solar storm particles.
Credit: NASA
SAN FRANCISCO: Scientists have found two holes in Earth's protective magnetic shield, letting in particles from solar storms that could wreak havoc on satellites and electrical equipment.
The holes are a startling discovery that change the way scientists think about Earth's invisible magnetic field, said Jimmy Raeder, a U.S. space physicist from the University of New Hampshire in Durham.
Raeder was part of the team who presented the discovery at yesterday's meeting of the American Geophysical Union in San Francisco, California.
Leaky shield
Scientists have long known the magnetic field surrounding our planet, called the magnetosphere, plays a crucial role in protecting us from particles blasted towards Earth by the Sun's solar wind.
Though most of these energetic particles are deflected by the magnetosphere, some do manage to breach the shield.
Previously it was thought the solar particles could enter more easily when the Sun's magnetic field was pointing in the opposite direction of Earth's field. When the two fields were pointing in the same direction, however, they were believed to reinforce each other, acting as a barrier to lock most of the particles out.
Backwards thinking
But that theory turns out to be backward, said Marit Oieroset, a physicist at the University of California, Berkeley, also part of the research team. In fact, Oieroset said, 20 times more solar particles enter when the fields of the Sun and Earth are aligned.
The discovery was made when a fleet of five NASA satellites, known as THEMIS (Time History of Events and Macroscale Interactions during Substorms), traveled through a thick layer of solar particles inside the magnetosphere, said Oieroset.
The size of the fleet meant measurements could be made spanning the entire layer of particles, almost 6,500 km thick and rapidly growing, revealing the true extent of the magnetosphere's 'leak'.
The origins of the leak have been pinpointed to two holes that frequently develop on the side of the magnetosphere facing the Sun - one over the Northern Hemisphere, one over the Southern.
