It is also difficult to see events which happen very rapidly or very slowly or are too far away. Telescopes first enhanced our vision. Using telescopes the moons of Jupiter were discovered and studied for the first time, creating whole new fields of scientific study such as planetology and extraterrestrial geology. Later, cameras permitted permanent visual images to be recorded. Soon after their development, cameras became one of the first true remote sensing tools when they were first flown on balloons, then airplanes and later spacecraft.
Special films extend the range of cameras beyond visible light to infrared and ultraviolet.
Modern remote sensing includes the entire electromagnetic spectrum from radio waves through microwaves, millimeter waves, submillimeter waves, infrared, visible, ultraviolet, x-ray and gamma rays. The spectrum range is important because the world looks differently at different parts of the spectrum due to variations in electrical and mechanical properties. In the visible light range we call this effect 'color'. Color helps discriminate between objects and various surface properties. High altitude aircraft and satellites allow acquisition of remotely sensed data over large scale regions, giving us a global view of the Earth.