Cosmic Pebbles Give Us Pause Must Worlds Collide Before Human Beings Get Things Right?

Posted: March 21, 1998

In recent days we have heard a lot about an awesome asteroid zooming toward us, with a slight chance of plunging right into our land or water with incalculable harm to life and civilization.

Scientists assure us there is no cause for alarm, but it is fair to say that in the decades to come cults and soothsayers will sprout like wild weed; petty prophets will quote scriptures to remind us of the promised end, and vendors of T-shirts and trinkets will make a quick buck.

Let us reflect a little. In the memorable year of 1789, when the French Revolution exploded, Giuseppe Piazzi furnished his observatory in Palermo, Sicily, with new equipment. His was the southernmost observatory in Europe. On Jan. 1, 1801, the first night of the 19th century, Piazzi stumbled on an object unseen by any human eye till then. It turned out to be the first asteroid to be discovered. Piazzi named it Ceres, the patron goddess of Sicily.

The astronomer William Herschel called it an asteroid (``starlike''). More exactly, it is a planetoid, for, like the planets of our system, it orbits our sun. The current technical term for an asteroid is ``small or minor planet.'' But the original, etymologically inappropriate name still persists in popular books and in the media.

More than 100,000 asteroids are estimated to be whirling around, the vast majority in the space between Mars and Jupiter. About 7,000 have been individually spotted, named and catalogued. The thousandth asteroid was discovered in 1923 and named Piazzia in honor of Piazzi. Other asteroids bear such names as Gaussia and Rockefellia.

Asteroids are for the most part irregular chunks of rock from a fraction of a mile to a few miles across. It was once speculated that they are perhaps splinters from what may have once been an entire planet which, for some reason, split into smithereens. The region peppered by this rocky junk cluttering the calm void of interplanetary space, but trapped by the gravitational pull of our central star, is picturesquely described as ``the asteroid belt.'' If they are many in number, they are meager in mass: Their combined mass would barely add up to 5 percent of the mass of the moon.

As petty planets way out there, they are mere astronomical curiosities, like some wild beasts roaming the Antarctic wilderness. And they are as likely to disturb us as a remote creature from the southern polar regions is likely to stray into downtown Anchorage. But should they come to our vicinity, it will be a little more unpleasant than an unwelcome cousin dropping in for dinner. There are about 11 whose orbits, we know, lie within our earth's. These Aten asteroids (as they are called) are potential threats to human survival. Minuscule as they are in mass and size (in astronomical terms), because of their terrific speeds, they carry stupendous kinetic energy. That is why any encounter with them would be a deadly affair. So - not just out of scientific curiosity - we have been surveying, measuring and keeping track of these celestial punies.

Asteroids are the only astronomical entities in which the House of Representatives has ever taken any interest. Thanks to them, sizable appropriations have been allotted for projects like NEAR (Near Earth Asteroid Rendezvous) and Spaceguard Survey. Armed with supercomputers, scientists have been able to conceptualize the impact of an asteroid assault on the earth - and it is not a pretty picture. The resulting environmental disaster from a decent-size asteroid would make the Hiroshima episode look like an accident in a fireworks display. Its bang would create unimaginable havoc of vast proportions, causing irreparable damage to air and water, and killing hundreds of millions of human beings. Such events are known to have happened before, but long before the advent of Homo sapiens.

There was an age in which scientific ignorance prompted our ancestors to fear distant constellations, planets and comets as controlling our lives and foreboding disasters. The word disaster, in fact, means ``bad star.'' But now, ironically, enriched by scientific knowledge, we are frightened, not by mammoth and majestic stars, but by pebbles in the cosmic sea, unworthy by size alone of serious attention. Little did Piazzi realize to what fears his discovery would lead.

Perhaps we can learn something from this deadly possibility. The mere contemplation of a global decimation of our species, transforming into smoke and ash much of our art and music and science, our love and joys and laughter, erasing so much of the human presence, should make us pause to wonder whether all the sectarian hatred and squabbles, the virulent racism and religious feuds that degrade our spirit, are worth a cosmic penny.

V.V. Raman is professor of physics and humanities at the Rochester Institute of Technology.