The sky is not falling. Oh, we do (occasionally) we see meteors that are somewhat like small sand grains that hit the Earth’s upper atmosphere at such speeds that they burn up, producing the bright streaks known, erroneously, as “shooting stars.” Even more rarely a larger bit of space rock will survive that atmospheric encounter and make it to the surface of the Earth as a meteorite. But meteorites are rarely dangerous. There is only one known case where a meteorite actually hit a person, in Alabama in 1954, although it did cause serious bruising of that person’s hip.
In 2014 there was a near disaster when a large 20-meter diameter meteor exploded about six miles above the Siberian town known as Chelyabinsk, and the shock ways from that explosion broke thousands of windows and indirectly caused hundreds of mostly minor injuries.
In 1972 there was another near-disaster when a truck-sized meteor skipped across the upper atmosphere high above the northwest US, much as you can make a rock skip across the surface of a pond if you show it at a sufficiently narrow angle. It was so bright it was seen and photographed in daylight. In 1947 a meteorite made of metal, known as the Sikhote-Alin meteorite, exploded high in the atmosphere over Siberia spreading many tons of shrapnel over dozens of square miles.
About a century ago, the famous 1908 Tunguska meteor (or perhaps comet) exploded over the Siberian town of the same name, flattening forests over an area of thousands of square miles. That explosion was equivalent to as much as 1000 WWII Hiroshima atomic bombs. Fortunately, the location was far from habitations and no known injuries occurred.
When we consider longer periods of time in Earth History there are indeed asteroid impacts that have caused considerable damage. Every school child learns about the asteroid impact known as the Cretaceous-Tertiary (KT) event that wiped out the dinosaurs (and over 75 percent of all species of life on Earth) about 65 million years ago. That was the equivalent of about one million Hiroshima bombs. And there is evidence of even larger impacts in Earth history.
These are not fictional. Such impacts occur with a rather well known frequency. A Tunguska type impact occurs about every hundred years — so we are “due” one about now. But the larger they are the more infrequent they occur. But they do occur.
There are other dangers from space as well. Storms in the sun’s atmosphere are so energetic that they send out high energy charged atoms which, when they hit the Earth’s upper atmosphere, sometimes cause the pretty aurora borealis — northern lights. But those are tiny storms compared to what happens occasionally on the sun. In 1859 a solar storm known as the Carrington event hit the Earth that caused the few electrical power transformers in Boston to explode.
If such an event happened now, it would wipe out dozens of satellites in Earth orbit, including communication, GPS, and weather satellites. It would cause global electrical power disruptions and blackouts. The damage that would occur from such an event is estimated at roughly one trillion dollars — that is one million, million dollars — enough to even get the attention of congress. It would be a global disaster that could take decades from which to recover.
And such catastrophic solar storms are estimated to occur about every century. In 2012 a solar storm hit Mars that would have been of similar size to the 1859 event. We learned about it because of Mars MAVEN spacecraft in orbit around Mars happened to detect it. It was directed away from the Earth, so we were not in danger.
These types of space dangers are not ignored. NASA is working diligently to discover and map the orbits of all of the larger near-Earth asteroids that could hit the Earth and cause widespread damage. There are hundreds of thousands of them. And the field of Space Weather has efforts aimed at understanding solar storms and their propagation from the sun to the Earth.
The “sky” is not falling — today. But it will in the future. Depend on it. Obviously it is not profitable, nor possible, to worry about everything bad that can happen. That would paralyze our everyday activities, and would be very unhealthy mentally. But it is wise to know about such dangers and to plan for probable likely but infrequent events that are known to happen — occasionally.
Michael Summers is a professor of planetary science and astronomy at George Mason University.
The views and opinions expressed in this commentary are those of the author and do not reflect the official position of The Daily Caller.