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One photogenic planet.

Satellite images provide a startling panorama of Earth and its vibrant systems, while revealing the impacts of humankind.

If a picture is worth a thousand words, the images on these pages could fill volumes. They were all photographed over the past few years by info-gathering satellites orbiting the globe. At first glance, the photos may seem like obscure, abstract blobs with swirling colors and speckled patterns. But a closer look reveals a clearer-than-ever snap-shot of planet Earth as a pulsing, changing whole.

For instance, focus on the brown patch in the "tie-dye" shot, above. What land mass you can identify? The twisting colors to its right mapt out the Gulf Stream, the tropical ocean current that moves warm, equatorial waters of the Atlantic Ocean north along America's east coast.

Scientists know that the Gulf Stream plays an essential role in balancing Earth's heat budget--how much solar energy the planet absorbs and releases back to the atmosphere. Without this current's constant flow, the tropics would be too hot to sustain life, and the polar regions too cold.

But what if ocean temperatures increase slightly in the next century, as predicted by global warming? Will the Gulf Stream carry even more warmth to the north and melt the polar ice cap? If so, will sea levels rise and flood coastal cities?

Scientists don't have all the answers yet. But with satellite images, they can closely monitor subtle trends in ocean temperature and thereby predict with more precision the effects of climate changes.

NEW HORIZONS

As you continue to view these photos, you may notice how strikingly different each one appears. The reason: Different types of remote sensors were used to image Earth's varied components--not only seas, but also air, land, and life.

By pooling the data collected by these sensors, researchers have shaped a new scientific disclipline: Earth system science. In this field, researchers study how Earth's living and nonliving components interact.

For example, some satellites are equipped with cameras, which capture on film the spectrum of visible light rays reflected from Earth. Examples include broad views showing the distribution different plant species or soil types. This information may help scientists locate the most fertile lands.

Weather satellites, including the one that measures Gulf Stream temperatures, have sensors that pick up infrared (heat) rays. Other sensors analyze levels of compounds in Earth's atmosphere, including ozone and carbon dioxide.

Perhaps the most useful feature of satellite imaging is that remote sensors can "see" during day or night, and collect data despite clouds and storms.

THE DARK SIDE

While broad views from satellites present a spectacular display of Earth, they also show us the dark side: how human activities have altered our environment.

You've heard the warnings before, but now you can see hard evidence: Sweeping photos of the destruction of Earth'sf forests; the draining of seas for agriculturalf use; the artificial glow of electric lights, often burning fossil fuels wastefully day and night, while obscuring astronomers' views of the night sky.

Scientists hope that by seeing the "big picture" of Earth's natural systems and by glimpsing the scope of human-induced changes, people will wake up and take action. As one scientist points out, these photos are a timely reminder that we must take care of the planet that sustains us. For now, at least, it is our only home.
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Title Annotation:satellite images of Earth
Author:Freiman, Chana
Publication:Science World
Date:Jan 14, 1994
Words:556
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