MODIS (or Moderate Resolution Imaging Spectroradiometer) is a key instrument aboard the
Terra (EOS AM) and Aqua (EOS PM) satellites. Terra's orbit around the Earth is timed so
that it passes from north to south across the equator in the morning, while Aqua passes
south to north over the equator in the afternoon. Terra MODIS and Aqua MODIS are viewing
the entire Earth's surface every 1 to 2 days, acquiring data in 36 spectral bands, or
groups of wavelengths (see MODIS Technical Specifications). These data will improve our
understanding of global dynamics and processes occurring on the land, in the oceans,
and in the lower atmosphere. MODIS is playing a vital role in the development of
validated, global, interactive Earth system models able to predict global change
accurately enough to assist policy makers in making sound decisions concerning the
protection of our environment.