By creatively using a radio telescope to see in 3D, astronomers have detected the existence of tubular plasma structures in the inner layers of the magnetosphere surrounding the Earth.
“For over 60 years, scientists believed these structures existed but by imaging them for the first time, we’ve provided visual evidence that they are really there,” said Cleo Loi of CAASTRO at the University of Sydney.
“The discovery of the structures is important because they cause unwanted signal distortions that could, as one example, affect our civilian and military satellite-based navigation systems. So we need to understand them,” Ms Loi, the lead author of this research, said.
The region of space around the Earth occupied by its magnetic field, called the magnetosphere, is filled with plasma that is created by the atmosphere being ionised by sunlight.
The innermost layer of the magnetosphere is the ionosphere, and above that is the plasmasphere. They are embedded with a variety of strangely shaped plasma structures including, as has now been revealed, the tubes.
“We measured their position to be about 600 kilometres above the ground, in the upper ionosphere, and they appear to be continuing upwards into the plasmasphere. This is around where the neutral atmosphere ends, and we are transitioning to the plasma of outer space,” explained Ms Loi.
Using the Murchison Widefield Array (MWA), a radio telescope located in the Western Australian desert, Ms Loi found that she could map large patches of the sky and even exploit the MWA’s rapid snapshot capabilities to create a movie – effectively capturing the real-time motions of the plasma.
“We saw a striking pattern in the sky where stripes of high-density plasma neatly alternated with stripes of low-density plasma. This pattern drifted slowly and aligned beautifully with the Earth’s magnetic field lines, like aurorae,” Ms Loi said.
