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Why Is the Sky Blue?
The daytime sky is blue because of what happens to sunlight as it enters the Earth's atmosphere. When the Sun is low near the…
What Puts the Chew in Chewing Gum?
The "chew" in chewing gum is provided by a chewy plastic mixed with natural gums from trees. At the chewing-gum factory, the chewy gum…
What Makes Plant Leaves Green?
What Makes Plant Leaves Green? The green we see in leaves comes from a green substance called “chlorophyll,” which the plant uses in mak
How Do We Measure the Height of a Mountain?
How Do We Measure the Height of a Mountain? Most of our figures for mountain heights were obtained with an "altimeter." This is kind…
What Is Local Mean Sea Level?
What Is Local Mean Sea Level? Sea level is the base level for measuring elevation and depth on Earth. Because the ocean is one…