An airborne/spaceborne oil spill detection method includes the step of providing a moderate-resolution-imaging-spectroradiometer and sensing the spectral reflections from two optical bands one of which is in the near infrared range. The spectral contrast shift from two adjacent areas of water are calculated and a warning issued when an oil spill or other contaminant is detected. A system for detecting an oil spill or other contaminant on the surface of water is also disclosed.