Since a supemova will not remain visible to the naked eye for more than a year or so even under the best condi tions (at the distance of the Galactic nucleus), the second supemova would not be visible until long after the first had faded off to invisibility.

In short, the 5,000,000 supemovas, forming in a sphere 850 light-years in diameter, would be seen by us to appear over a stretch of time equal to roughly a thousand years.

If the explosions started at the near edge of that sphere so that radiation had to travel away from us and return to set off other supernovas, the spread might easily be 1500 years.

If it started at the far end and additional explosions took place as the light of the original explosion passed the pre supernovas en route to ourselves, the time-spread might be considerably less.

On the whole, the chances are that the Galactic nucleus would begin to show individual twinkles. At first there might be only three or four twinkles a decade, but then, as the decades and centuries passed, there would be more and more until finally there.might be several hundred visible at one time. And finally, they would all go out and leave behind dimly glowing gaseous turbulence.

How bright will the individual twinkles be? A single supemova can reach a maximum absolute magnitude of - 17. That means if it were at a distance of 10 parsecs (32.5 light-years) from ourselves, it would have an appar ent magnitude of -17, which is 1/10,000 the brightness of the Sun.

At a distance of 30,000 light-years, the apparent magni tude of such a supemova would decline by l0 magnitudes.

The apparent magnitude would now be -2, which is about the brightness of Jupiter at its brightest.

This is quite a static statistic. At the distance of the nucleus, no ordinary star can be individually seen with the naked eye. The hundred billion stars of the nucleus just make up a luminous but featureless haze under ordinary conditions. For a single star, at that distance, to fire up to the apparent brightness of Jupiter is simply colossal. Such a supemova, in fact, burns with a tenth the light intensity of an entire non-exploding galaxy such as ours.

Yet it is unlikely that every supemova forming will be a supemova of maximum brilliance. Let's be conservative and suppose that the supemovas will be, on the average, two magnitudes below the maximum. Each will then have a magnitude of 0, about that of the star Arcturus.

Even so, the "twinkles" would be prominent indeed. If humanity were exposed to such a sight in the early stages of civilization, they would never make the mistake of think ing that the heavens were eternally fixed and unchangeable.

Perhaps the absence of that particular misconception (which, in actual fact, mankind labored under until early modern times) might have accelerated the development of astronomy.

However, we can't see the Galactic nucleus and that's that. Is there anything even faintly approaching such a multi-explosion that we can see?

There's one conceivable possibility. Here and there, in our Galaxy, are to be found globular clusters. It is estimated there are about 200 of these per galaxy. (About a hundred of our own clusters have been observed, and the other hundred are probably obscured by the dust clouds.)

These globular clusters are like detached bits of galactic nuclei, 100 light-years or so in diameter and containing from 100,000 to 10,000,000 stars-symmctricary scat tered about the galactic center.

The largest known globular cluster is the Great Hercules Cluster, M13, but it is not the closest. The nearest globular cluster is Omega Centauri, which is 22,000 light-years from us and is clearly visible to the naked eye as an object of the fifth magnitude. It is only a point of light to the naked eye, however, for at that distance even a diameter of 100 light years covers an area of only about 1.5 minutes of arc in diameter.

Now let us say that Omega Centauri contained 10,000 pre-supemovas and that every one of these exploded at their earliest opportunity. There would be fewer twinkles altogether, but they would appear over a shorter time in terval and would be, individually, twice as bright.

It would be a perfectly ideal explosion, for it would be unobscured by dust clouds; it would be small enough to be quite safe; and large enough to be sufficiently spectacular for anyone.

And yet, now that I've worked up my sense of excite ment over the spectacle, I must admit that the chances of viewing an explosion in Omega Centauri are just about nil.

And even if it happened, Omega Centauri is not visible in New England and I would have to travel quite a bit south ward if I expected to see it high in the sky in full glory and I don't like to travel.

Hmm… Oh well, anyone for a neighborhood fire?