The weather cleared and steadied for a while (days and nights were
indistinguishable during the long Antarctic winter) and I split my time
evenly between monitoring the meteorological sensors and observing the
stars. The snow had covered the dome completely, of course, but our
"snorkel" burrowed through it and out into the air.
"This dome's just like a submarine, only we're submerged in snow
instead of water," Rizzo observed. "I just hope we don't sink to the
bottom."
"The calculations show that we'll be all right."
He made a sour face. "Calculations proved that airplanes would never
get off the ground."
The storms closed in again, but by the time they cleared once more,
Rizzo had completed the image-amplifier for me. Now, with the tiny
telescope I had, I could see almost as far as a professional instrument
would allow. I could even lie comfortably in my bunk, watch the
amplifier's viewscreen, and control the entire set-up remotely.
Then it happened.
At first it was simply a curiosity. An oddity.
* * * * *
I happened to be studying a Cepheid variable star--one of the huge,
very bright stars that pulsate so regularly that you can set your
watch by them. It had attracted my attention because it seemed to be
unusually close for a Cepheid--only 700 lightyears away. The distance
could be easily gauged by timing the star's pulsations.[1]
[Footnote 1: _Astronomers have been able, since about 1910, to estimate
the distances of Cepheid variable stars by timing their pulsations.
The length of this type of star's pulsation is a true measure of its
intrinsic brightness. Comparing the star's actual brightness to its
apparent brightness, as seen from Earth, gives a good value for the
star's distance._]
I talked Rizzo into helping me set up a spectrometer. We scavenged
shamelessly from the dome's spare parts bin and finally produced an
instrument that would break up the light of the star into its component
wavelengths, and thereby tell us much about the star's chemical
composition and surface temperature.
At first I didn't believe what I saw.
The star's spectrum--a broad rainbow of colors--was criss-crossed with
narrow dark lines. That was all right. They're called absorption lines;
the Sun has thousands of them in its spectrum. But one line--_one_--was
an insolently bright emission line. All the laws of physics and
chemistry said it couldn't be there.
But it was.
We photographed the star dozens of times. We checked our instruments
ceaselessly. I spent hours scanning the star's "official" spectrum
in the microspool reader. The bright emission line was not on the
catalogue spectrum. There was nothing wrong with our instruments.
Yet the bright line showed up. It was real.
"I don't understand it," I admitted. "I've seen stars with bright
emission spectra before, but a single bright line in an absorption
spectrum! It's unheard-of. One single wavelength ... one particular
type of atom at one precise energy-level ... why? Why is it emitting
energy when the other wavelengths aren't?"
Rizzo was sitting on his bunk, puffing a cigaret. He blew a cloud of
smoke at the low ceiling. "Maybe it's one of those laser signals you
were telling me about a couple weeks ago."
I scowled at him. "Come on, now. I'm serious. This thing has me
puzzled."
"Now wait a minute ... you're the one who said radio astronomers were
straining their ears for nothing. You're the one who said we ought to
be looking. So look!" He was enjoying his revenge.