By Peter Becker
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When do the greatest percentage of Americans pull themselves away from their TV sets, computers and other indoor activities, and go outside after dark and look up? Would you say when there is an eclipse? A meteor shower? Try Fourth of July!
As pretty as fireworks are, who hasnít grumbled when it takes a few seconds too long between firing off another rocket? Alas, we have come to expect everything fast. The adage, "good things come to those that wait" perhaps is more timely a message than ever.
Enjoying the heavens above takes some time and patience. The sky seems so static and unchanging- except of course when a meteor startles us. Although the stars and planets are actually hurtling through space at astonishing speed, due to the vast distances involved, things look quite steady to our eyes. All the stars move east to west as the Earth turns, but you donít notice the motion at a glance.
Add some magnification with a telescope, and you will see how fast things can be. High power, say 100X and greater, will cause a star or whatever you are looking at to slip out of view quickly. Without a motor drive as some telescopes have, you will need to gently nudge your telescope tube along to keep the celestial object in view.
The Earth travels in its orbit at 18.55 miles a second. That is not easy to imagine. In the time it takes you to read only a couple words of this column, the world - with you on it - has leaped over 18 miles. At the same time, Earth is being whisked along with the sun and other planets in an enormous orbit around the galaxy - it takes an estimated 225 million years to go once around! The sun and planets are moving at 135 miles a second. The velocity of the entire Milky Way Galaxy, relative to neighboring galaxies, has been estimated at 621 miles a second.
Physicists teach that the maximum possible speed is that of light, which exceeds 186,000 miles per second. Even at that fantastic rate, star light takes years to reach us; the Alpha Centauri star system is the closest to the Sun and the light reaches us in 4.3 years. Light from nearby galaxies takes millions of years. Sunlight is eight minutes old once it reaches your eyes. Stars are constantly on the move as they whisk around the Milky Wayís center, yet from hundreds or thousands of light years away, to detect their motion in respect to neighboring stars takes years, using telescope instrumentation.
Yet for all that motion, the stars seem still as can be to our unaided eyes, thanks to the great distances involved. The Big Dipper your great, great, great grandfather saw is essentially the same as what you may see tonight!
The moon is a thick crescent on July 4, and reaches first quarter on the 5th.
Enjoy the fireworks, and the cosmic show above them!
Keep looking up!
Looking Up: Fireworks and the stars
By Peter Becker