London, Dec. 17: A geophysicist has made the first-ever measurement of the strength of the magnetic field inside the Earth’s core, 1,800 miles underground, by using the moon and distant quasars.
Mr Bruce A. Buffett, professor of earth and planetary science at the University of California, Berkeley, used radio observations of the quasars to get precise measurements of the Earth’s rotation axis and how the tug of the moon on that axis affected its magnetic field.
He said the magnetic field strength is 25 Gauss, about 50 times stronger than the field at the surface that makes compass needles align north-south, reports Nature.
Though this number is in the middle of the range geophysicists predict, it puts constraints on the identity of the heat sources in the core that keep the internal dynamo running to maintain this magnetic field.