Superconductivity and carbon nanotubes, are Type I, while almost all impure and compound superconductors are Type II. Conversely, a spinning superconductor generates a magnetic field, precisely aligned with the spin axis. The effect, the London moment, was put to good use in Gravity Probe B. This experiment measured the magnetic fields of four superconducting gyroscopes to determine their spin axes. This was critical to the experiment since it is one of the few ways to accurately determine the spin axis of an otherwise featureless sphere. Superconductivity was discovered on April 8, 1911 by Heike Kamerlingh Onnes, who was studying the resistance
Kamerlingh Onnes (crater) Kamerlingh Onnes (crater) Kamerlingh Onnes is a lunar impact crater on the far side of the Moon. It lies less than a crater diameter to the north-northwest of the crater Kolhörster. North of Kamerlingh Onnes lies Shternberg and to the northwest is Weyl. This is a worn and eroded crater formation that is slightly elongated along the east–west direction, giving it a somewhat oval shape. A number of small craters lie along the rim, particularly along the northern side. The interior floor is marked only by a few small craterlets, and some ray material from the crater Ohm to the