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The Goldilocks Effect: Earth Is Just Right
Book Chapter |
Complex life forms require certain conditions to thrive. The distance from a star at which an Earth-like planet could sustain life is known as the habitable zone—not too close, not too far, but just right. …
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The Formation of the Solar System
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Over the last four centuries, people have developed many theories to explain the origin and evolution of the solar system. Today, the theory most commonly held by scientists is known as the solar nebula theory. In this…
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Book Chapter |
The stars are too far away to measure their distance directly, so astronomers use an indirect method that involves looking at the star from two or more perspectives. They measure how much the foreground star’s position…
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Habitable Zone: How Distance and Temperature Are Related
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Earth is the only planet we know of in the solar system that supports life. In this activity, students will investigate the way distance from a light source affects temperature—one of the many reasons why Earth is “just…
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Book Chapter |
Earth is an extremely complex system with many components and subsystems, and they all interact and affect each other. The four major subsystems are atmosphere (air), lithosphere (land), hydrosphere (water), and…
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Book Chapter |
Global warming is happening now, and scientists have evidence that humans are to blame. The rate of warming in the past 50 years has doubled, and temperatures are certain to go up even more. To gain an understanding of…
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Creature Feature: Comparing Earth to Mars and Venus
Book Chapter |
Mars and Venus are Earth’s closest neighbors. The differences between them are striking. In many ways, Earth can be thought of as the happy medium between the two extremes that Mars and Venus represent. In this activity…
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Book Chapter |
Water is such an integral part of human existence that it makes up nearly three-quarters of Earth’s surface and has a profound effect on all life on Earth. Water vapor in the atmosphere accounts for just one-thousandth…
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Book Chapter |
Sailors have known for centuries that ocean currents can speed up or slow down a ship. In modern times, scientists have discovered that ocean currents have major effects on climate and weather patterns, and on the…
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Book Chapter |
Waves are among the most common phenomena in nature. Waves breaking in the ocean, sound, light, microwaves, radio, or the motion of a guitar cord or a drum are all forms of waves. Such diversity makes finding common…
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What are some of the ways you can make waves in water? Have you ever jumped into a pool or lake and done a “cannonball”? This makes waves. The largest water waves on Earth are found in the oceans, and most ocean waves…
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Tanks a Lot—Activities for a Wave Tank (Teacher Demonstration)
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Some concepts related to waves, though, are difficult to demonstrate in the classroom. They require observing water waves on a scale that is not ordinarily feasible for the classroom teacher because the necessary…
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Book Chapter |
Anyone who has been to the coast realizes there is a rhythm to the ocean. Waves crash onto the beach or rocks. The water they carried washes ashore, then retreats. Another wave crashes ashore. The pattern repeats.…
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The Sun, Moon, and Earth are three extremely large objects separated by great distances. Despite the large distances between them, each object affects the others. Earth is kept in orbit around the Sun by the…
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The Bulge on the Other Side of Earth
Book Chapter |
The bulge of water on the side of Earth that faces the Moon is easily explained. It is due to the gravitational attraction between the Moon and Earth, including the water on Earth. The difference on the horizontal…
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