Venus’ Interesting Magnetic Structure
Venus may be similar to Earth in size and mass, but there are differences between the two planets. One difference is the magnetic field. On Venus, a magnetic field isn’t generated by the planet, like Earth’s. It is actually an induced magnetosphere, a region of charged particles around the planet formed by a reaction between Venus’ ionosphere and the solar wind. New research shows that there are holes void of magnetically charged plasma in a region where such plasma is expected to be.
The holes were first noticed when the Pioneer Venus Orbiter moved around the backside of the planet back in 1978. Since then, the holes have not been detected again.
Recently, researchers studying data from the Venus Express orbiter decided to look for the holes again. They found them and realized that they were more common than initially thought, visible over a broad range of solar activity.
When the solar wind hits Venus, it wraps around the planet and a long tail extends behind it. This is what creates the magnetosphere. The Venus Express orbiter took measurements of the magnetic field strength and found variations that indicated the presence of these holes. The observations suggest that these holes are actually not just holes, but take the shape of long cylinders directed out towards space.
But what is causing these cylinders to form? In addition to the solar wind wrapping around the planet to create the magnetosphere, the researchers propose that the magnetic field lines from the solar wind is able to continue into the planet and wrap around its core, something that is also seen on the Moon. As a result, the electrically charged plasma is pushed to the sides and this is what created the two cylinders found behind the planet by the orbiters.
More information can been seen in the NASA video above, the press release, and the journal paper (paywall).