The magnetosphere, which is the shield of ions and electrons that envelops Earth, extends far beyond the atmosphere, defending the planet from the harmful solar wind.
Now, according to a report in National Geographic News, Charles Chappell, a physicist at Vanderbilt University in Nashville, Tennessee, led a research team that assembled information dating back decades to describe a new layer.
Some of the first hints of the cloak first showed up in data from research satellites in the early 1970s. The cloak was finally confirmed by NASA's Polar satellite, which ended a 12-year run in April 2008.
The cloak's discovery creates a theoretical home for particles that didn't fit with any of the other understood parts of the Earth's magnetosphere, according to Chappell.
The cloak's tails billow in response to the direction of solar winds.
"The cloak particles didn't fit with any of the other regions," said Chappell.
Chappell and his colleagues called the layer the "warm plasma cloak" because it conjured an image for them of a person on a horse, wearing a long cloak.
Plasma is ionized gas found in space.
The warm plasma cloak begins thinly on the nightside-or darkside-of the planet and wraps around to the dayside, where it becomes thickest until noon.
In the afternoon, convective winds push the cloak out toward the edge of the magnetosphere, where it's peeled off by solar winds.
Depending on where it is relative to Earth, and the energy of the solar wind, the cloak can be found anywhere from 13,000 to 65,000 miles (20,000 to 105,000 kilometers) above the Earth's surface. It is always thickest on the planet's dayside.
The formerly mysterious warm plasma cloak is also implicated in one of the menacing effects of the magnetic field-damage to dozens of human-made satellites over the years.
"The warm plasma cloak is part of the environment that communications and weather satellites fly in," Chappell said. "It will play a role in how much the spacecraft charge electrically," he added. (ANI)