A giant underground motion sensor in Germany tracks Earth’s wobbles
A giant underground motion sensor in Germany has taken its first measurements of Earth’s spin and tilt. Although researchers are still getting the machine’s accuracy up to snuff, their observations could someday keep GPS navigation working reliably on devices like smartphones. Phenomena like earthquakes and ocean tides continually knock Earth’s rotation off-kilter, requiring constant correction of GPS satellite signals. Typically, corrections use telescope observations, which offer a set of celestial coordinates to determine Earth’s orientation in space. But telescope data can take days to process. The Rotational Motions in Seismology, or ROMY gyroscope array, can monitor Earth’s tiny wobbles continuously, researchers demonstrate in an experiment reported online July 17 in Physical Review Letters. ROMY is an upside-down pyramid of pipes, about the length of a telephone pole on each side. Its four triangular faces measure motion in different directions. On each side, one laser beam runs clockwise through the triangular piping, while...