READ: Gallery — Earth From Space

Satellite photography of Earth shows some astonishing things about our planet and our relationship with it.

Human populations have contributed to desertification in many parts of the world through deforestation and poor farming techniques that degrade the soil. In this photograph of the Wadi As-Sirhan Basin of Saudi Arabia, humans are transforming longtime desert land into farm land with complex irrigation systems. To get an idea of size scale, each circle – some of them with active crops (green) and some fallow (brown) – is about one kilometer in diameter. A variety of crops are grown in this region including fruits, vegetables, and wheat.

Two time periods meet in this photograph of the Great Pyramids of Giza, built more than 4,000 years ago, and the modern metropolitan area of Cairo. Monumental architecture was one of the defining characteristics of the first agrarian civilizations and today's societies continue in that tradition.

In this image of Tokyo, the city sends tendrils of light for miles out from its center. Tokyo is one of the largest cities in the world, with more than 13 million people. As a point of comparison, in 1800 Tokyo had a population of less than 1 million. World population has grown at about the same pace. Today there are more than 7 billion people in the world and that number is expected to exceed 8 billion within this century.

The Amazon jungle is one of the most biologically diverse areas of the planet. Vast, and rich in vegetation, the Amazon's capacity for absorbing carbon dioxide from the atmosphere is immense. However, deforestation and severe droughts have compromised the health of the rainforest. In the decade from 1991 to 2000, a tract of land the size of Spain was cleared for agriculture and development. Deforestation has slowed down in recent years but thousands of square kilometers are still cleared every year.

Oil spills like the Deepwater Horizon incident in the Gulf of Mexico in 2010 highlight the importance of fossil fuels to modern civilization and point out some of the dangers we face. As growing population and consumption drives increasing energy needs, our impact on the biosphere increases too.

Reductions in both the thickness and overall area of ice sheets and glaciers such as those in Greenland are one indicator of global climate change. As more of the Arctic and Antarctic ice melts, sea levels will rise and weather patterns will change.

The Northwest Passage is a sea route running between the waters along the top of the North American continent and the polar ice cap. Explorers have attempted to find a northern shortcut between Asia and Europe since the end of the 15th century but no one was able to "make the Northwest Passage" until early in the 20th century. Recent climate change has opened up the gap in the ice for longer periods of time and now there are cruise ships that ply these waters in the summer months.

Hurricane Sandy formed on October 22, 2012 and lasted until the end of the month. It is one of the largest Atlantic hurricanes on record, with winds spanning 1,100 miles, and was the second-costliest hurricane in US history. Many scientists believe that weather patterns will become more severe, and more unpredictable, as global climates change.