The “Glory” of Stars
HAVE you ever gazed in wonder at the thousands of stars visible on a clear night? As you looked at those twinkling points of light, you may have noticed that they vary in brightness and even in color. “Star differs from star in glory,” the Bible correctly states.—1 Corinthians 15:41.
Why do stars differ in their glory, or radiance? Why, for example, do some look white and others blue, yellow, or red? And why do they twinkle?
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. Why the color difference?
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.
Earth’s Atmosphere “Colors” the Sun
We see the sun through the filter of the atmosphere, which alters the sun’s appearance to varying degrees, depending on the time of day. At midday, for example, the sun normally has a bright-yellow hue. But at sunrise and sunset, when it sits low on the horizon, it may appear orange or even red. This color change occurs because of gas molecules, water vapor, and various microscopic particles in earth’s atmosphere.
Because of its composition, the atmosphere scatters blue and violet solar light, producing a gorgeous blue sky on a clear day. With blue and violet subtracted from the sun’s visible spectrum, the remaining direct sunlight at midday is dominantly yellow. But when the sun is very low on the horizon, its light travels through the atmosphere at a sharp angle before it reaches us. As a result, sunlight passes through more of the atmosphere, which now scatters even more light in the blue range, as well as green light. Hence, the setting sun may appear as a magnificent red or crimson ball.
The Colorful Night Sky
Our view of the night sky is influenced considerably by the sensitivity of our eyes. Our eyes receive light through two kinds of sensors—cones and rods. Cones distinguish color, but in very dim light, they stop functioning. The rods, however, while not sensitive to color, are extremely efficient photoreceptors. Indeed, under optimal conditions, a rod may be triggered by a single photon of light! The sensitivity of our rods, though, is shifted toward the shorter wavelengths found at the blue end of the spectrum. As a result, when, with the naked eye, we look at faint stars of the same brightness, we will likely see the blue ones but not the red ones. Thankfully, though, we are not restricted to the naked eye.
Binoculars and telescopes increase our ability to see faint objects in the night sky, such as stars, galaxies, comets, and nebulae. Even so, our view is somewhat compromised by the atmosphere. A solution to this problem is the Hubble Space Telescope, or HST, which is in orbit around the earth. A technological marvel, the HST can detect objects that are just one ten-billionth as bright as the faintest stars visible to the naked eye! As a result, the HST has produced truly stunning views of objects in deep space, including galaxies and clouds of interstellar dust and gas called nebulae.
That said, new earth-based telescopes now rival and even exceed the HST in certain ways. For example, using ingenious corrective techniques for the effects of the atmosphere, these new telescopes enable astronomers to see in greater resolution, or detail, than they can by means of the HST. One example is the W. M. Keck Observatory on the island of Hawaii, which houses the Keck I telescope, one of the largest optical telescopes in the world. By means of this telescope, astronomer Peter Tuthill of the University of Sydney, Australia, discovered dust clouds being ejected by binary-star systems in the Sagittarius constellation, which from our viewpoint appears to be near the center of our galaxy, the Milky Way.
The deeper that astronomers peer into space, the more stars and galaxies they find. How many are out there? We can only guess. But that is not so of our Creator, Jehovah God. “He is counting the number of the stars; all of them he calls by their names,” says Psalm 147:4.
The prophet Isaiah made similar expressions. In fact, he went a step further, stating with remarkable scientific accuracy that the material universe is a product of God’s infinite energy. “Raise your eyes high up and see,” Isaiah wrote. “Who has created these things? It is the One who is bringing forth the army of them even by number, all of whom he calls even by name. Due to the abundance of dynamic energy, he also being vigorous in power, not one of them is missing.”—Isaiah 40:26.
How did Isaiah, who lived some 2,700 years ago, know that the universe is a product of God’s infinite energy? He certainly did not figure that out himself! Rather, he wrote what Jehovah inspired him to write. (2 Timothy 3:16) Thus, he, as well as the other Bible writers, did something no science textbook or telescope can do. They identified the One who gave the stars their beauty and glory.
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WHY DO STARS TWINKLE?
Stars twinkle, or appear to change slightly in brightness and location, because of disturbances in earth’s atmosphere. To illustrate, imagine tiny points of light on the bottom of a swimming pool. What happens to those lights as ripples pass over them? Yes, they twinkle, just as stars do. Larger lights, on the other hand, would be less disturbed. Planets are like those larger lights, not because they are bigger than stars, but because they are much closer to the earth and thus seem bigger.
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IMAGE COLOR: TRUE OR FALSE?
Thanks to the Hubble Space Telescope (HST), likely you have seen spectacular, colorful images of galaxies, nebulae, and stars. But are the colors real? The fact is, they are a re-creation, a blend of art and science. The images received from the HST are monochrome but are taken through color filters. Astronomers and imaging specialists use modern technology and software to compose the final images, at times to reproduce as closely as possible what they believe to be the natural colors of heavenly objects. * At other times, astronomers deliberately produce false-color images to make certain things stand out, perhaps for scientific analysis.
^ par. 21 When we use a telescope to observe faint objects in the night sky, our cone cells pass the task of seeing to our rod cells, which cannot perceive color.
Final image after combining the three colors
J. Hester and P. Scowen (AZ State Univ.), NASA
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The star V838 Monocerotis
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Interacting galaxies Arp 273
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NASA, ESA, and the Hubble Heritage (STScI/AURA) -ESA/Hubble Collaboration
[Picture Credit Lines on page 16]
V838: NASA, ESA, and H. Bond (STScI); Arp 273: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)