meteor – n. a piece of rock or metal that burns and glows brightly in the sky as it falls from outer space into the Earth's atmosphere
meteorite - n. a meteor that reaches the surface of the earth without being completely destroyed
sensor – n. a device that responds to a physical stimulus such as heat, light, sound, pressure, magnetism, or a particular motion and then sends a resulting impulse (as for measurement or operating a control)
seismic – adj. of or relating to earthquakes or other vibrations of the earth and its crust.
hydrostatic - adj. of or relating to fluids at rest or to the pressures they exert or transmit
ultrasound – n. a method of producing images by using a machine that produces sound waves which are too high to be heard
Radioactivity – n. the property possessed by some elements (as uranium) or isotopes (as carbon 14) of spontaneously emitting energetic particles (as electrons or alpha particles) by the disintegration of their atomic nuclei. (Whew, that is a tough one!)