How come the stars never change?

Stars are light sources, great nuclear engines spewing out their electromagnetic signals into space. They are a great distance from the earth, the nearest—other than the sun—being 4.3 light-years away. Light travels at about 186,000 miles [299,000 km] per second. Because the light from stars travels so far to reach us, it becomes rather feeble. It then must pass through the increasing density of earth’s atmosphere, which bends the light rays this way and that. If it twinkles, it is a star
Stars hold within their core immense nuclear furnaces that generate enormous amounts of energy. That energy migrates to the star’s outer layers, where it radiates into space, largely as visible light and infrared rays. Hotter stars, you may be surprised to learn, are blue, whereas cooler stars are red. Reason for the color difference is. Light can be thought of as a stream of particles, called photons, which also behave as waves of energy. Higher temperature stars emit higher energy photons, which have the shorter wavelengths found at the blue end of the spectrum. Conversely, cooler stars give off lower energy photons, which are toward the red end of the spectrum. Our own star, the Sun, lies toward the middle because it emits a larger amount of light in the green-to-yellow range. Why, then, does it not look greenish? It emits a lot of light in the other visible wavelengths as well. The net result, when viewed from space, is a white sun.
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