Discovery School - 100 Greatest Discoveries - Earth Science
1. Earth's Core (1906) Seismologist Richard Oldham determines that earthquake waves move through the central part of the Earth much slower than through the mantle around it. He surmises that the Earth has a core composed of liquid.
2. Earth's Inner Core (1930s) In 1936, Inge Lehmann documents that some seismic waves from deep inside the Earth's core do not pass through, but are reflected back. It becomes clear that the Earth has an inner core consisting of a small, solid iron sphere that is surrounded by a thick outer core composed of liquid iron.
Dog-eared Paperback of My Life by Lucius Shepard: The main premise behind this story isn't that a significant event (or insignificant, even) happened differently, but instead that a bunch of alternate Earths have converged. An author discovers a book by himself that he never wrote, which is the beginning of his discovery that these different versions of the Earth sometimes meet, sometimes briefly, sometimes not.
Infinite Worlds . . . Infinite Adventure! The good news is, there are other Earths. Maybe an infinite number. The bad news is, somebody out there doesn't like us. The shuttles of Infinity Unlimited jump between parallel Earths, seeking adventure, profit, knowledge, and even entertainment. But a parallel called Centrum has also developed the technology to hop between the worlds . . . and they want to rule them all.
This book features essential coverage of all major aspects of Earth's solar system, from every feature of the major planets to their satellites, small bodies, interplanetary phenomena, and cosmological context. Designed to meet the needs of both general readers and students, this completely revised and updated edition covers 180 major topics on Earth's solar system as it is understood from the latest perspectives.
Why are there seasons each year? Is it cold in December because the Earth is farthest from the sun at that time? If the Earth is closest to the sun in summer, why is it winter in New Zealand and warm in the Northern Hemisphere? Studying the reason behind the change of seasons can be confusing, but Bill Nye is on top of it. In Bill Nye the Science Guy: Earth's Seasons, he demonstrates the reasons for the cycling of seasons, and makes it very clear why Christmas comes in summer in Australia.