Huge underground lasers measure Earth’s spin with extreme precision

Deep inside a concrete-filled pit just outside Munich, Germany, researchers are taking some of the best measurements ever of Earth’s motion. They are using huge, red lasers set 15 metres below Earth’s surface to get data that could help make GPS navigation more precise.

GPS uses measurements from satellites which have to be calibrated with measurements of Earth’s orientation in space, which is constantly changing. “If we don’t measure it, our GPS location that we have in our car and our phone would be…