Multilayer PCBs, especially when designed for RF, may have many layers of ground; even the signal layers typically have ground flooded on them. ... The via spacing was set to 200 mils, this ...

Astronomers have creatively used a radio telescope to see in 3-D, allowing them to detect the existence of tubular plasma structures in the inner layers of the magnetosphere surrounding the Earth.

Earth is made up of several layers: the lithosphere, asthenosphere, lower mantle (also known as mesospheric mantle), outer core and inner core.