People always say that space is a vacuum. That’s true – space is about a thousand times emptier than even the best laboratory vacuums on Earth. Even so, space contains lots of stuff we can’t see. We study this invisible space stuff because we need to understand it to safely send technology and astronauts into space.
The stuff that fills space is mostly plasma, which is gas where particles have separated into positive ions and negative electrons, creating a sea of electrically-charged particles. This plasma also contains something else – magnetic fields.
The particles in space can reach very high speeds, creating radiation. One of the main engines that drives that acceleration to high speeds is called magnetic reconnection. But what is magnetic reconnection?
Magnetic reconnection happens when two oppositely-aligned magnetic fields pinch together and explosively realign. As the lines snap into their new configuration – as in the animation below – the sudden change sends electrons and ions flying at incredible speeds.
Magnetic reconnection releases energy. We can’t see the energy itself, but we can see the results: It can set off solar explosions – such as solar flares and coronal mass ejections – or disturbances near Earth that cause auroras.
In March 2015, we launched the four Magnetospheric Multiscale, or MMS, spacecraft on a mission to study magnetic reconnection. Magnetic reconnection only happens in a vacuum with ionized gas. These conditions are vanishingly rare on Earth, so we went to space to study this explosive process.
Because MMS has four separate – but essentially identical – spacecraft, it can watch magnetic reconnection in three dimensions.
The below animation shows what MMS sees – the magnetic fields are magenta, positive ions are purple, and electrons are yellow. The arrows show which the direction the fields and particles are moving.
Like how a research plane flies through a hurricane, MMS flew directly through a magnetic reconnection event in October 2015.
In the data visualization below, you can see the magnetic reconnection happening as the yellow arrows (which represent electrons) explode in all directions. You’ll notice that the magnetic field (represented by magenta arrows) changes direction after the magnetic reconnection, showing that the magnetic field has reconfigured.
Magnetic reconnection transfers energy into Earth’s atmosphere – but it’s not inherently dangerous. Sometimes, the changes in Earth’s magnetic field caused by magnetic reconnection can create electric currents that put a strain on power systems. However, the energy released is more often channeled into auroras, the multicolored lights that most often appear near the North and South Poles.
As the MMS mission continues the four spacecraft can be moved closer together or farther apart, letting us measure magnetic reconnection on all different scales. Each set of observations contributes to explaining different aspects of this invisible phenomenon of magnetic reconnection. Together, the information will help scientists better map out our space environment — crucial information as we journey ever farther beyond our home planet.
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