Techers Richards and Song Prove Earth Spins at Varying Speeds

Caltech alumni Paul G. Richards (MS '66 GE, PhD '70 GEPH) and Xiaodong Song (MS '91 GEPH, PhD '94 GEPH) have confirmed assertions first made in 1996 that the earth's inner core, a ball of solid iron larger than the moon, spins faster than the rest of the planet. Over a period of 700 to 1,200 years, the inner core appears to make one full extra spin.