The Interactions Between the Sun and Earth

Earlier this year Mark and I completed work on a series of video podcasts called Space Weather FX. It was funded by NASA through MIT’s Haystack Observatory, and is aimed at helping people understand the interactions between the solar wind and Earth’s geomagnetic system. The series is getting some serious play around the world and we’re pleased about that. It means that people are learning just what the effect of solar activity can be on our fragile planet.

What’s just as cool is that the European Space Agency’s Cluster series of satellites — each named after a different saucy dance: Samba, Salsa, Tango, and Rumba, have been operating for a decade, giving scientists a constant stream of data that allows them to construct a virtual 3D “picture” of how the solar wind (that stream of charged particles that moves constantly out from the Sun), affects our planet and its protective magnetic shield called the magnetosphere.

Cluster’s keen observations of magnetic field interactions have revealed how the solar wind can often penetrate the magnetosphere whipping up giant magnetic whirlpools that can spread highly energetic particles (called plasma) into the upport part of our atmosphere called the ionosphere. What’s more, it has looked carefully at a strange phenomenon called “black auroras” — a sort of “anti-aurora” that sucks electrons from Earth’s ionosphere.

The action of the solar wind and its interaction with the magnetic field of our planet generates huge electrical currents that can be measured. There are also collisions of massive, strong magnetic fields during those interactions. When those collisions take place, there’s a huge release of energy. But there’s also the creation of a central region called a “null point.”  Cluster has given scientists a way to study such a null point, helping them better understand the physics of a magnetic reconnection event.  Now, everything that Cluster studies is mostly invisible to us. We can’t stare at the solar wind and see these magnetic reconnection events.  But, Cluster’s sensitive instruments can track the interactions that so fascinate solar physicists.  It’s a great leap forward for solar physics and I hope that the mission continues for another decade — probing the often violent interactions between Sun and Earth’s magnetosphere.