What is the remote sensor pointing straight down from the aircraft in a line perpendicular to Earth's surface known as?

The term used to describe a remote sensor that points directly down from the aircraft in a line perpendicular to the Earth's surface is "Nadir." This positioning is crucial for various geospatial applications, including remote sensing and aerial photography, as it enables the most accurate data capture of the Earth's surface.

When a sensor is oriented toward the nadir, it can effectively gather images or measurements without distortion that may occur from off-angle views. This direct vertical perspective ensures that the data collected is representative of the area directly below the aircraft, making it ideal for mapping, land use classification, and other analyses where a precise view of the terrain is essential.

In contrast, the other terms do not accurately describe this specific orientation of the sensor. For example, "Zenith" refers to the point in the sky directly above the observer, while "Vertical View" might imply an upright perspective but does not specifically refer to the nadir. "Ground-based Position" typically describes terrestrial surveying rather than aerial sensor orientations. Thus, recognizing nadir as the proper term solidifies understanding of sensor functionality in aerial data collection.