The aberration of starlight proved the central idea of: (a) copernicus's heliocentric cosmos (b) kepler's 4th law of orbital motion (c) eratosthenes' measurement of earth's circumference (d) newton's law of gravity (e) galileo's theory of the moon's phases

The space within which a test north pole experiences a force magnetic poles 2. a powerful stream of electrons flowing high above the earth in the ionosphere electrojet 3. a concept to explain the directional nature of a magnetic field field lines 4. coil of wire designed to produce a magnetic field by a current passing through its windings ionosphere 5. that region above the earth's atmosphere where particles exist in an ionized state magnetic field 6. the extremities of a magnet where the field lines tend to converge or concentrate aurora borealis 7. a phenomenon that occurs in the northern latitudes; the northern lights solenoid