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.

MODIS was launched on the EOS Aqua spacecraft on Saturday, May 4, 2002 at 09:55 GMT. MODIS Aqua "First Light" was achieved when the MODIS Nadir Aperture Door opened on June 24, 2002 at 23:22:48 GMT. The Aqua MODIS instrument began taking data using side-B electronics. For a complete look at the EOS-PM/ Aqua mission, see http://aqua.nasa.gov/.

MODIS was launched on the EOS Terra spacecraft on Saturday, December 18, 1999 at 18:57 GMT. MODIS Terra "First Light" was achieved when the MODIS Nadir Aperture Door opened on February 24, 2000. The Terra MODIS instrument began taking data using side-A electronics. For a complete look at the EOS-AM/ Terra mission, see http://terra.nasa.gov/. To read more about MODIS visit http://modis.gsfc.nasa.gov