What term describes the view from an aircraft directed straight downward toward the Earth's surface?

• A. Nadir
• B. Zenith
• C. Horizon
• D. Baseline

Answer: (A)

When you look straight down from an aircraft toward the Earth's surface, that point directly beneath you is called the nadir. The nadir is the position on the surface that lies exactly under your feet, opposite of the zenith, which is directly overhead. The horizon is where the sky seems to meet the ground at eye level, not a vertical downward direction. Baseline is unrelated to the vertical view and refers to a starting reference line in measurements. In drone work, nadir imagery specifically refers to downward-looking views captured from the aircraft.