2 · en
Short, simple sentences with “wavelengths”, suitable for children and primary/elementary school, with common expressions and related words. You'll also find examples for middle and high school.
The most accurate knowledge about nebulae has only come from spectroscopy, a method of breaking down light and photographing the wavelengths - the colours - that make up the light. The dark lines that may appear signify an absorption by some chemical element. As each element absorbs a certain frequency, we know what nebulae are made of.
Ozone is formed when hard ultraviolet rays - very short wavelengths - break oxygen molecules in two, resulting in free oxygen atoms that rejoin with some of the abundant oxygen molecules, forming the valuable gas. This photochemical activity produces about 5000 molecules per second, which concentrate to form the ozone layer which, due to chlorofluorocarbons, is on the verge of extinction.
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