Nadir is employed during remote sensing of the atmosphere, as well as when an astronaut faces the Earth while performing a spacewalk. The term nadir can also be used to represent the lowest point reached by a celestial body during its apparent orbit around a given point of observation. This can be used to describe the location of the Sun, but it is only technically accurate for one latitude at a time and only possible at the low latitudes. The sun is said to be at the nadir at a location when it is at the zenith at the location's antipode
Point-to-Point Protocol over Ethernet computer or from the DSL-AC. PPPoE is used to connect a PC or a router to a modem via an Ethernet link and it can also be used in Internet access over DSL on a telephone line in the "PPPoE over ATM" (PPPoEoA) over ADSL protocol stack. PPPoE over ATM has the highest overhead of the popular DSL delivery methods, when compared with for example PPPoA (RFC 2364). The amount of overhead added by PPPoEoA on a DSL link depends on the packet size because of (i) the absorbing effect of ATM cell-padding (discussed below), which completely cancels out additional