Today, if we could somehow visit our ancient ancestors and show them the bounty of modern science and technology, we would be viewed as magicians. With the wizardry of science, we could show them jet planes that can soar in the clouds, rockets that can explore the moon and planets, MRI scanners that can peer inside the living body, and cell phones that can put us in touch with anyone on the planet. If we showed them laptop computers that can send moving images and messages instantly across the continents, they would view this as sorcery.
The atmosphere brims with tiny aerosol particles—such as sea salt, sulfates, and dust—that come from both natural and human activities. Though they aren’t always visible to the human eye, satellite sensors can reveal global patterns. This image, created using NASA MODIS data highlights the global distribution of the particles.
Larger aerosols (shown in green) tend to have natural sources: Salt aerosols are visible over the oceans, and a dust is visible over the Saharan desert. Finer-grained urban aerosols are concentrated over the eastern United States and eastern Asia, particularly China. The fine aerosols in subtropical Africa are related to agricultural fires.
In the desert of southwest Peru, between the Andes Mountains and the Peruvian coast, lies a plateau with huge geometric patterns and spirals, animal figures including a monkey, a spider, and an ‘owl man,’ and thousands of perfectly straight lines. The last of these was drawn about a thousand years ago. Known as the Nazca lines, the drawings have mystified scientists since they were first discovered in the 1920s