FOR those of us who missed it, there's scant solace in knowing that Halley's Comet will be back again on April 29, 2061. On the positive side, fuel shortages may have so darkened night skies by then that our city-dwelling descendants will be able to see the comet with their naked eyes. But on the other hand, who can predict with certainty that any cities will be left standing 75 years hence?
Travelling at 80,156 miles an hour, Halley's Comet streaked past the earth on April 11, leaving our long-suffering species in its dust; the solar system had ticked off another interval of history to which, for better or worse, none may ever return. Few of us will have a chance of seeing the comet again, and its passing, like that of a birthday, may prompt some unwelcome thoughts.
For anyone feeling particularly deprived, however, astronomers are offering a new and provocative perspective. It seems that our entire corner of the universe - the Virgo Supercluster, the Milky Way and the IRT Broadway Line included - is careening along so fast that even the comet's sizzling velocity seems glacial by comparison.
In the five centuries since Copernicus demolished the ancient vision of a geocentric universe, most of us have come to accept a notion of the earth as a moving cog in a clockwork cosmos. Renaissance scholars made this unsettling idea a little easier to swallow by pointing out that although we were moving, the motions of all heavenly bodies tended to take the form of tidy, predictable orbits; the planets kept time with the celestial Music of the Spheres.
But seven American and British astronomers have reported evidence (gleaned partly from analyses of the orbital motions of stars in distant galaxies) that we are not only flying through space some 500 times faster than a speeding bullet, but we are caught up in a cosmic stampede - a mad, collective rush toward a spot in the sky marked by the Southern Cross constellation.Continue reading the main story
We've known for a long time, of course, that the earth is not exactly gathering moss. Our axial rotation alone imparts a speed of 1,038 miles an hour to anyone standing at the Equator. To this must be added another 66,700 miles an hour, earth's orbital speed around the sun. And finally, astronomers estimate that the entire solar system is circling the Milky Way galaxy at a speed of some 605,000 miles an hour.
But the latest news, from the National Optical Astronomy Observatories, is that some 400 elliptical galaxies, our Milky Way among them, seem to be linked together in a wild charge toward some unknown but common goal. We are scudding along, moreover, at a brisk one million miles an hour.
A million miles an hour may not seem very fast compared with the overall expansion rate of the universe. Astronomers judge that the most distant galaxies are receding from each other at speeds not much less than that of light itself: 670.2 million miles an hour. But the odd thing about the new finding, which was based on six years of complex observations, is that so many objects are flying so fast in the same direction.
The 400-odd galaxies involved, each containing roughly 100 billion stars and grouped into four ''superclusters,'' occupy a space some 350 million lightyears across - a sizable proportion of the entire observable universe. It would take a truly cosmic agency to move such a titanic mass in unison, and astronomers can suggest only two possible causes.
One possible cause is a hypothetical explosion that might have occurred soon after the Big Bang genesis event, an explosion powerful enough to channel vast amounts of speeding matter into a common direction. The alternative explanation is that somewhere out beyond the Southern Cross there may be a gigantic blob of matter exerting enough gravitational pull to haul 400 billion stars along at one million miles an hour.
Both explanations seem to raise more questions than they answer. For one, will our hard-charging Milky Way ever approach that mysterious magnet beyond the Southern Cross, or shall we merely rush forever onward, as aimless in our flight as the phantom ship Flying Dutchman?
Either way, Halley's comet will remain relatively close by, even when it again reaches the end of its tether at the edge of the solar system. The disappearance of the comet for another three-quarters of a century is no real loss, for it remains a member of our little solar family, and we're all headed the same way, wherever that may be.Continue reading the main story