Tuesday, February 19, 2013

A Unique Astronomical Event



Last week, a hunk of space rock 50 feet across slammed into our planet in Russia. No one was hurt directly from the meteorite as it exploded about 12 miles up. But the shock wave shattered windows and falling glass sent more than 1000 folks to the hospital for treatment.

Is this unusual? NASA scientists say an impact of this magnitude is a once-a-century event. The last impact from an object in that size range occurred in 1908, also over Russia. One has to wonder what Russia has done to anger the universe.

The last time any object from space hit Earth was about a second ago. Whoops, there goes another. And another. Truth is, 50,000 pounds of stuff from space comes to Earth every year. At night, we see them as shooting stars. During daylight hours, we don’t see them at all, unless they happen to be big enough to glow brighter than the daylight sky. And they occur over land. Where there are people living. Since most of our planet is oceans, most such events occur over water. Most of the land of Earth is uninhabited, so most meteorites go completely unseen by humans.

That’s the normal state of affairs for a planet, nothing unusual abut it. In fact, our Moon formed when a rock so large we call it a planetoid slammed into Earth 4.5 billion years ago. The debris from that massive collision coalesced into our moon.

Yes, these things can be very dangerous. Just ask the next dinosaur you meet. But big ones, ones that generate significant damage, are quite rare. The little ones, the ones we can experience every clear night, are common.

Would you like to see an absolutely unique astronomical sight, one that no one has ever seen or ever will again? You can, and it’s not the least bit dangerous.

Wait until it gets dark tonight. Go outside and look at the night sky. Look carefully. Do you see it? It is unique in all of the history of the universe.

It is tonight's sky.

As the planets move in their annual dance around the sun, as our sun orbits the center of the Milky Way galaxy, and as other stars move under the various gravitational influences that direct their motions, the sky is eternally changing. The sky has never looked exactly as it does tonight and will never do so again.

This is the true magic of astronomy. You never get reruns. Each night remains unique. So, enjoy this night sky, because it will be different tomorrow.

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