----- Have you had a chance recently to see the mystical Northern Lights dance across the sky? Now seems like a pretty good time to start looking! "Why?", you ask? Well, the Sun has just begun emerging from the deepest "solar minimum'' in the past 100 years. As it climbs toward "solar maximum'', the activity of our Solar System's central star is on the rise, and with it the chances of more intense auroral displays. The Sun bombards Earth's magnetic field with ionized gases of the solar wind plasma to create colorful aurorae. Credit: SOHO (ESA & NASA) Everyday, particles of the solar wind -- charged plasma flowing outward from the Sun -- bombard Earth's predominantly dipolar magnetic field. (Think about iron filings and a bar magnet to visualize a magnetic dipole). Ionized particles spiral toward the North and South Poles along the lines of Earth's magnetic field. Nitrogen and oxygen atoms in the atmosphere are excited by the incoming plasma, and when the atoms return to their ground states, they release the extra energy as colorful bursts of green and red photons of light. Ionized nitrogen also emits brilliant blue flashes as it regains its missing electron. These ethereal flashes of light are the aurorae.
David Baker is the Chairman of the Physics Department at Austin College, and Todd Ratcliff is a planetary geophysicist at NASA's Jet Propulsion Laboratory. They are the authors of The 50 Most Extreme Places in the Solar System, which Discover Magazine Online called an "extremely interesting book" from "two extremely fascinating gentlemen." Below, Baker and Ratcliff explain the Northern Lights, solar activity, and why physicists know not to ditch their landlines.
But mild magnetic storms that merely spice up the aurora are just a warm-up for our Solar System's most extreme magnet. Massive outbursts from the Sun can wreak havoc on the sensitive electronics that are interwoven into our modern lives. In 1859, the most powerful solar storm ever recorded (a solar superstorm!) caused telegraph stations to burst into flames and aurorae to be seen as far south as Hawaii. In 1989, power to the entire Canadian province of Quebec was knocked out as a consequence of a massive CME.
Today we are more vulnerable than ever to the vagaries of extreme storms on the Sun. Satellites, cell phones, power grids...all could fall victim to gigantic electromagnetic outbursts. Because of this, space weather is an active and vital area of research. Fortunately, solar scientists are predicting a rather mild solar maximum for Sunspot Cycle 24 (our current cycle). But space-based solar observatories such as the Solar & Heliospheric Observatory (SOHO), Solar Dynamics Observatory (SDO), and others are keeping an eye out just in case.
The next time you hear about increased geomagnetic activity or solar flares, look poleward at night. See if you can spot the ghostly flickers. You just might be able to see first-hand one of the Solar System's most radical electrical light shows! And with a little luck, you can reach your friends on your static-filled (yet still working) cell phone to brag about it!
