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Natural and artificial substances in the atmosphere that affect human health or well-being, or the well-being of any other organisms in the environment. Air pollution also applies to situations in which contaminants affect structures and artifacts…

An ongoing current event in which a large number of living species are threatened with extinction or are going extinct because of environmentally destructive human activities. The Earth is presently in the midst of a mass extinction event. In the…

The interdisciplinary study that attempts to determine how much astronomy prehistoric people knew and how it influenced their lives. Archeoastronomy (Fig. 1) involves multiple disciplines: astronomy to chart the heavens, archeology to probe the…

Humans have used dried bovine dung (manure) as a fuel source since prehistoric times. In India, for example, many people burn cow or buffalo dung for cooking fuel. This bioresource provides a low-cost fuel as well as an efficient means of waste…

Cameras in mobile phones or smartphones that can capture images and videos.The cellphone, the world’s favorite must-have gadget, has been with us for nearly a half-century, while experiencing continuous and often phenomenal improvements. Much of the…

Light emitted by a high-speed charged particle when the particle passes through a transparent, nonconducting, solid material at a speed greater than the speed of light in the material. The emission of Cerenkov radiation—also spelled Cherenkov—is…

Wind-pollinated plants—including trees, grasses, and weeds—produce most of the pollen that affects seasonal allergy sufferers. Wind-pollinated plants produce great amounts of pollen grains that are very small in size. For example, one ragweed plant…

Systems that use mirrors to reflect and concentrate sunlight onto a central receiver where it is collected and converted to heat that is used to produce electricity by conventional means. The main drives for developing reliable sources of renewable…