Liquid helium of liquid water. Helium was first liquefied on July 10, 1908, by the Dutch physicist Heike Kamerlingh Onnes at the University of Leiden in the Netherlands. At that time, helium-3 was unknown because the mass spectrometer had not yet been invented. In more recent decades, liquid helium has been used as a cryogenic refrigerant, and liquid helium is produced commercially for use in superconducting magnets such as those used in magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR), Magnetoencephalography (MEG), and experiments in physics, such as low temperature Mössbauer spectroscopy. The temperature required to produce liquid helium is low because
Kamerlingh Onnes (crater) northeast. 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