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How Big is the Earth? (1:43)
How big is the Earth? Find out in this HowStuffWorks video!
Sir Martin Rees Talks About Earth (18:11)
Watch this video showing how the Earth works on HowStuffWorks. Cosmologist Sir Martin Rees explains why the 21st century is a unique and pivotal century not just for mankind but for the entire planet. Learn about how the Earth works in this video... More »
Sketches of the World: Introduction to Nature (2:08)
The natural world contains many different landscapes and life forms. Mountains are some of the most visible landscapes, but many other landscapes also exist.
Life in the Desert: Interactions Among Species (3:55)
Desert plants and animals form relationships with others that share their habitat to form a biological community. A keystone species is a species that dominates an ecosystem in numbers and in its importance to other species.
Life in the Desert: Animal Adaptations (2:24)
Desert animals have a variety of adaptations. Some avoid intense heat by moving around or limiting activity during the hottest part of day. Raptors fly up high on cool airstreams to avoid the heat.
