NASA’s website for the Landsat program quotes the baseball player Yogi
Berra, saying “You can see a lot by just looking”. If you’ve never heard
of the Landsat program before, that quote pretty much sums it up. There
have been eight Landsats since 1972, and their purpose from the
beginning was to take photographs of the earth. And by photographing the
same place over 40 years, these photos give amazing insights into
things like soil erosion, the effects of natural disasters, and the
migration of penguin colonies.

Alaska’s Columbia Glacier: The Columbia Glacier descends from an ice
field 3,050 meters (10,000 feet) above sea level, down the flanks of the
Chugach Mountains, and into a narrow inlet that leads into Prince
William Sound in southeastern Alaska. It is one of the most rapidly
changing glaciers in the world. This false-color image, captured by the
Thematic Mapper (TM) instrument on Landsat 5, show the glacier and the
surrounding landscape in 2011. Snow and ice appears bright cyan,
vegetation is green, clouds are white or light orange, and the open
ocean is dark blue. Exposed bedrock is brown, while rocky debris on the
glacier’s surface is gray.
Yukon
Delta: Countless lakes, sloughs, and ponds are scattered throughout
this scene of the Yukon Delta in southwest Alaska. One of the largest
river deltas in the world, and protected as part of the Yukon Delta
National Wildlife Refuge, the river’s sinuous waterways seem like blood
vessels branching out to enclose an organ.
Pretty much everyone knows the ‘
blue marble‘
image. Taken by the crew of Apollo 17 in 1972, it’s a picture of the
earth, framed against the vast emptiness of space. The image is common
now, but no one knew what the earth looked like from space until the
late 1960′s, when people actually went up there. And though we went up
to explore space, there was no denying the sudden appeal of the earth
below. For the first time we could really see the earth in all its
glory, and NASA and the Department of the Interior decided to see more.
So the Landsat program was born.
When Landsat 1 was being designed, a new type of imaging system was
installed, which could detect light wavelengths outside the visible
spectrum, like infrared. This was helpful in showing things like water
saturation in soil. So instead of trying to tell the difference between
slightly different shades of green, as you would in a ‘true color’
photograph, the imaging system could use other wavelengths and display
saturated areas in pink and dry areas in yellow. The different way of
looking meant greater understanding, and some amazing looking images.
Lake Eyre: The scary face in this image is actually inundated patches of
shallow Lake Eyre (pronounced “air”) in the desert country of northern
South Australia. An ephemeral feature of this flat, parched landscape,
Lake Eyre is Australia’s largest lake when it’s full. However in the
last 150 years, it has filled completely only three times.
Meandering
Mississippi: Small, blocky shapes of towns, fields, and pastures
surround the graceful swirls and whorls of the Mississippi River.
Countless oxbow lakes and cutoffs accompany the meandering river south
of Memphis, Tennessee, on the border between Arkansas and Mississippi,
USA. The “mighty Mississippi” is the largest river system in North
America.
Possibly even more amazing however, are the images that are ‘true color’. Red clouds, anyone?
WITH THANKS FROM NASA.