Observatorio del Roque de los Muchachos (IMAGE) Johannes Gutenberg Universitaet Mainz Caption The Observatorio del Roque de los Muchachos, located on the rim of an extinct volcano at 2,400 meters altitude in the island of La Palma, provides adequate conditions to perform the experiments described. Credit photo/©: Felipe Pedreros Bustos Usage Restrictions This image may only be used in connection with the press release "Earth's magnetic field measured using artificial stars at 90 kilometers altitude", issued by Johannes Gutenberg University Mainz on November 14, 2018. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.