Image Credit: NASA/Goddard Space Flight Center/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.
Original Caption: This is a diagram of the October 6, 2008, MESSENGER flyby that revealed magnetic tornadoes forming in Mercury's magnetic field. The tornadoes are corkscrew-shaped bundles of twisted magnetic fields and plasma. The pink area represents the boundary of Mercury's magnetic field, called the magnetopause. The tornadoes are technically known as "flux transfer events" (twisted lines) when they form at the magnetopause and "plasmoids" (yellow areas) when they form in the long magnetic "tail" extending from the night-side of Mercury. The large magnetic field leakage through the magnetopause and the flux transfer events acts as open channels through which the solar wind can flow down to the surface of the planet and sputter neutral atoms into Mercury’s atmosphere.