If you are bothered by things out of place, such as a picture hanging on the wall at a funny angle, don't let it spoil your view of the sky. Nothing is where it really us.
The Sun rises every day before it really does, and sets after it already did. The Moon does the same thing. For another reason, the stars you see tonight aren't necessarily where you are looking.
The Sun and Moon, as well as everything else Cosmic, when seen along a flat horizon, is affected by the Earth's atmosphere and throws their image off. The air around the Earth acts like a glass lens, and refracts, or bends, the light of the heavenly object, make it appear in a different place than it really is.
We are pretty well assured that the Sun will rise tomorrow. This is a wonderful constant in a world of change that we take so much for granted. The lens trick played by our atmosphere only adds to the beauty and drama of the sky.
The whole electromagnetic spectrum- which includes the entire rainbow of visible light, is refracted, at different amounts. Shorter wavelengths of blue and violet light are scattered away, and the longer wavelengths of orange and red are predominant. This gives the color of sunrise and sunset.
The bending of light at the horizon also leads to mirages and turbulence. Views of planets or the Moon as seen in a telescope are usually superior when viewed higher in the sky. No telescope is needed to see the effect of atmosphere on the shapes of the Sun and Moon, when very low in the sky. It can affect the timing of when you actually witness sunset and sunrise, as well as the Sun's position on the horizon and shape.
Stars and planets, as well as the Moon and Sun, are never seen exactly where they really are because of the great distances and time it takes their light to reach our eyes.
Light travels at 186,282.397 miles every second. Sunlight reaches us, on average, 1.282 seconds after reflecting off the Moon. The average velocity of the Moon in its orbit around the Earth is .64 miles a second. By the time the Moon's light reaches your eyes, the moon has traveled, on average, 8/10th of a mile along in its orbit (.82 mile or 643 and a half feet). "Average" is stressed because the Moon varies in velocity in its elliptical orbit, going fastest when closest to the Earth, and likewise varies in distance and thus the time it takes for the light to reach you.
The effect is far greater for stars. The bright red star Aldebaran, in the constellation Taurus the Bull, for instance, moves at 33.4 miles an hour through the Galaxy. The starlight takes 65 years to reach you, or about 569,400 hours. In the time it took the starlight to be seen, the star has moved 170,326 miles out of the way.
Page 2 of 2 - Constellations are imaginative pictures we make of the stars from our vantage point; the stars themselves are at widely different distances and are constantly on the move. Due to their great distance, however, the shape of a constellation would not begin to be noticeably but slightly different to the unaided eye for many thousands of years. Don't throw your childhood star chart out just yet.
Full Moon is on September 19.
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Keep looking up!