Satellite remote sensors view the Earth at many scales of space, ranging from global through
continental, regional, and localeven observing details as small as one meter (three feet)
across. These data enable scientists to study a wide range of phenomena that occur over these same scales of space, such as El Niño, droughts, storms, and flash floods.
The above image shows the Hollywood sign above Los Angeles, California. It is the final
frame in an animation that demonstrates the wide range of spatial resolutions viewed by current state-of-the-art sensors.
Farthest away in the animation, we see the Earth as a globe, which comes from data collected by the Moderate-resolution Imaging Spectroradiometer
(MODIS), an instrument on NASAs Terra satellite. This
first picture has a resolution of up to 8000 meters per pixel. As our
virtual camera begins its long descent to ground, we pass through another layer of
MODIS information. Data in the second layer resolves details as small as
250 meters across. Our measure of detail has just improved dramatically.
Next we find our apparent speed increasing as the surface of the Earth
envelops our sense of horizon. The data supporting this perspective
comes from the land imaging workhorse of NASAs fleet: Landsat 7. These images resolve features as small as 15 meters across.
Finally, as we rush in to the limits of Landsat 7s data capabilities,
we move to our final slice of visual information. Taken by a remarkable
commercial satellite called Ikonos, features as small as one meter
across come into view. Individual cars, trees, and baseball diamonds
can be easily distinguished on the ground. In virtual space weve
traveled more than a thousand miles, but in real terms only electrons, photons, and an elite group of computer and spacecraft personnel moved to make these images possible.