THE FAUIT IN OUR STAR

摘要

SHORTLY AFTER SUNSET ON JUNE 18,2013, a woman drove her minivan onto Brigh- ton Street in Belmont, Massachusetts. Her GPS told her to turn right. But the metallic voice, guided by satellite data, steered her wrong: onto a railroad track. She tried to drive off, but the van got stuck. No sooner had she unbuckled herself and her twokids and ushered them out than a train crumpled her car into a ball of foil. Not long after, someone sent a news story about the incident to space physicist Tamitha Skov. She didn't just see a GPS acting up. She saw the sun acting up. While our star looks calm and contained, its surface roils: Spots form and darken it like scabs; loops of plasma link its regions; its atmosphere streams farther outward than the star is wide. Solar flares, which are bursts of radiation, and coronal mass ejections, which are bombs of stellar material, disturb both Earth's magnetic field and upper atmosphere. There, they disrupt devices-like GPS receivers-that rely on electricity or radio communication. This interplay between the sun and Earth is called space weather, and it is Skov's specialty.