"A Look to the Earth"
"A new satellite photograph of Earth depicts our planet in all its aquatic splendor, revealing a truth somewhat obscured in the original Blue Marble image. That photograph is among the defining images of the 20th century. It gave humankind a new perspective on our planet, seen all at once against the backdrop of space — immense, beautiful, precarious. Much of Earth’s surface was covered by clouds, however, and what’s visible is dominated by Africa. A viewer’s eye is naturally drawn to the landmass; the same holds for updated Blue Marble images produced by NASA in 2001 and 2002, which center on North America and the Asian subcontinent. But with three-quarters of Earth’s surface covered by water — arguably the most important ingredient for life, and certainly the host of most life on Earth — it’s not land on which a planetary photographer should focus. It’s water. And so it is with this new NASA image, in which land is just barely visible as a fringe of the Pacific Ocean.
Click image for very large size.
In addition to restoring a certain geoscientific perspective, the photograph complements the original Blue Marble in another way. That image helped catalyzed an emerging environmental awareness, one conscious of both Earth’s beauty and humanity’s role as planetary steward. Nearly four decades later, our power to alter the environment is considered so profound as to define a new geological age, and even water is not exempt. “One of the unknowns concerning future climate change is what changes will occur in the water cycle. There are disagreements over this, but one possibility that has been suggested is that the water cycle might speed up,” said climatologist Claire Parkinson, lead scientist on NASA’s Aqua Project.
It may be that as temperatures rise, more water will evaporate, hastening its turnover in the atmosphere. On average, it now takes about nine days for an evaporated water molecule to come come back down. “The issue is by no means settled,” said Parkinson, and predictions are necessarily uncertain, but in the future it may take eight or even seven days. The water cycle could neatly fit a human week."
It may be that as temperatures rise, more water will evaporate, hastening its turnover in the atmosphere. On average, it now takes about nine days for an evaporated water molecule to come come back down. “The issue is by no means settled,” said Parkinson, and predictions are necessarily uncertain, but in the future it may take eight or even seven days. The water cycle could neatly fit a human week."
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