How the land has changed, not only down on the ground but from way out in space. There are many latest pictures produced by the sharp eyes of a government satellite known as Landsat 7.
Darrel Williams works on the NASA Landsat 7 Project. "We can see the conditions shortly after the eruption, when just a huge area was totally deforested, burned off. Now, 15 years after the fact, we can see light, pinkish view, which says vegetation is growing back. It's starting to reforest." he says.
Twenty-seven years of pictures have tracked the loss of rain forests in South America, as well as the clear-cutting of forests in the US Northwest.
Darrel Williams says, "Clearcut areas show up quite readily, and it shows we need to look at what's going on in our own backyard, as far as deforestation."
Landsat satellites have watched from space as glaciers have shrunk more than four miles over the past decade or so. This is a computer-animated view of Glacier Bay, Alaska, based on new pictures from Landsat 7.
Floyd and Irene show the heavy deposits of silt and farm runoff in coastal waters.
"And these show the increasing summer temperatures around Atlanta, Georgia", scientists say, " the condition is related to the loss of trees."
Darrel Williams says, "It's the most unique record of its type. It's like having a family photo album of anywhere on the globe. And if you don't think you've changed over time, just look at your pictures of the last 20 to 25 years."
Now, as Landsat 7 begins its work as the last in a series of earth observers, NASA readies an even more sophisticated satellite, Terra, due to be launched Thursday. Once it's working, Terra is expected to take the vital signs of the globe, including ocean temperatures, energy loss, and even the state of the atmosphere, every day.