A short history of nearly everything - Bill Bryson [17]
So when a hopeful and softspoken minister got in touch to ask if they had any usable field charts for hunting supernovae, the astronomical community thought he was out of his mind. At the time Evans had a ten-inch telescope—a very respectable size for amateur stargazing but hardly the sort of thing with which to do serious cosmology—and he was proposing to find one of the universe's rarer phenomena. In the whole of astronomical history before Evans started looking in 1980, fewer than sixty supernovae had been found. (At the time I visited him, in August of 2001, he had just recorded his thirty-fourth visual discovery; a thirty-fifth followed three months later and a thirty-sixth in early 2003.)
Evans, however, had certain advantages. Most observers, like most people generally, are in the northern hemisphere, so he had a lot of sky largely to himself, especially at first. He also had speed and his uncanny memory. Large telescopes are cumbersome things, and much of their operational time is consumed with being maneuvered into position. Evans could swing his little sixteen-inch telescope around like a tail gunner in a dogfight, spending no more than a couple of seconds on any particular point in the sky. In consequence, he could observe perhaps four hundred galaxies in an evening while a large professional telescope would be lucky to do fifty or sixty.
Looking for supernovae is mostly a matter of not finding them. From 1980 to 1996 he averaged two discoveries a year—not a huge payoff for hundreds of nights of peering and peering. Once he found three in fifteen days, but another time he went three years without finding any at all.
“There is actually a certain value in not finding anything,” he said. “It helps cosmologists to work out the rate at which galaxies are evolving. It's one of those rare areas where the absence of evidence is evidence.”
On a table beside the telescope were stacks of photos and papers relevant to his pursuits, and he showed me some of them now. If you have ever looked through popular astronomical publications, and at some time you must have, you will know that they are generally full of richly luminous color photos of distant nebulae and the like—fairy-lit clouds of celestial light of the most delicate and moving splendor. Evans's working images are nothing like that. They are just blurry black-and-white photos with little points of haloed brightness. One he showed me depicted a swarm of stars with a trifling flare that I had to put close to my face to see. This, Evans told me, was a star in a constellation called Fornax from a galaxy known to astronomy as NGC1365. (NGC stands for New General Catalogue, where these things are recorded. Once it was a heavy book on someone's desk in Dublin; today, needless to say, it's a database.) For sixty million silent years, the light from the star's spectacular demise traveled unceasingly through space until one night in August of 2001 it arrived at Earth in the form of a puff of radiance, the tiniest brightening, in the night sky. It was of course Robert Evans on his eucalypt-scented hillside who spotted it.
“There's something satisfying, I think,” Evans said, “about the idea of light traveling for millions of years through space and just at the right moment as it reaches Earth someone looks at the right bit of sky and sees it. It just seems right that an event of that magnitude should be witnessed.”
Supernovae do much more than simply impart a sense of wonder. They come in several types (one of them discovered by Evans) and of these one in particular, known as a Ia supernova, is important to astronomy because it always explodes in the same way, with the same critical mass. For this reason it can be used as a standard