The International Geophysical Year (IGY), increased research into space weather. Ground-based data obtained during IGY demonstrated that the aurora occurred in an auroral oval, a permanent region of luminescence 15 to 25 degrees in latitude from the magnetic poles and 5 to 20 degrees wide.[5] In 1958, the Explorer I satellite discovered the Van Allen belts,[6] regions of radiation particles trapped by the Earth's magnetic field. In January 1959, the Soviet satellite Luna 1 first directly observed the solar wind and measured its strength.