The THEMIS fleet was launched in February 2007 to unravel the mystery of substorms, which have long puzzled observers with their unpredictable eruptions of light and color. The spacecraft wouldn’t merely observe substorms from afar; they would actually plunge into the tempest using onboard sensors to measure particles and fields. Mission scientists hoped this in situ approach would allow them to figure out what caused substorms–and they were right.
The discovery came on what began as a quiet day, Feb 26, 2008. Arctic skies were dark and Earth’s magnetic field was still. High above the planet, the five THEMIS satellites had just arranged themselves in a line down the middle of Earth’s magnetotail—a million kilometer long tail of magnetism pulled into space by the action of the solar wind.
That’s when the explosion occurred.
A little more than midway up the THEMIS line, magnetic fields erupted, “releasing about 1015 Joules of energy,” says Angelopoulos. “For comparison, that’s about as much energy as a magnitude 5 earthquake.”
Although the explosion happened inside Earth’s magnetic field, it was actually a release of energy from the sun. When the solar wind stretches Earth’s magnetic field, it stores energy there, in much the same way energy is stored in a rubber band when you stretch it between thumb and forefinger. Bend your forefinger and—crack!—the rubber band snaps back on your thumb. Something similar happened inside the magnetotail on Feb. 26, 2008. Over-stretched magnetic fields snapped back, producing a powerful explosion. This process is called “magnetic reconnection” and it is thought to be common in stellar and planetary magnetic fields.
The blast launched two “plasma bullets,” gigantic clouds of protons and electrons, one toward Earth and one away from Earth. The Earth-directed cloud crashed into the planet below, sparking vivid auroras observed by some 20 THEMIS ground stations in Canada and Alaska. The opposite cloud shot harmlessly into space, and may still be going for all researchers know.
Auroras are special. Their light is different. The quantum physics behind them fascinating.
Aurora is the bringer of the dawn.
Dawn is coming.
Two plasma bullets.
One towards us, another towards others.
Only seen when in perfect alignment.
Between all bodies.
Saturn, the ever churning hexagon.
Star of David.
Portal to other worlds.
You can only hear it when properly aligned.
Tune in Tokyo.
Cosmic breasts, lactating ambrosia of life.