Despite their elusive nature, neutrinos were detected using special equipment
placed deep underground, so other forms of radiation were blocked by the mass
of the earth’s crust above. It was assumed that all the detected neutrinos would
have to come from extraterrestrial sources, mainly the sun. Far fewer neutrinos
were observed than theory predicted. The sun was supposed to be emitting a lot
of neutrinos, but it wasn’t! Measurement errors were dismissed as a possible
cause of these unexpected results; the equipment was tested and found to be
working properly. The only plausible solution to this puzzle was that the center
of the sun, from which a furious barrage of neutrinos was supposed to be ema-
nating, is far less hot than had been previously thought, and that nuclear fusion—
the only possible source of solar energy—is not presently taking place there!
One way out of this conflict between theory and experiment can be called the
solar thermostat theory. According to this theory, the solar furnace is off at the
present time. How long has it been off, and when will it start up again? We can-
not be sure about that, but if the solar thermostat theory does represent the facts,
it can provide an explanation for the occurrence of ice ages. According to the
theory, the sun is cooling off right now. This implies that the earth’s climate was
once warmer than it is today, and at that time the solar furnace was on. The
warmest periods would coincide to those times when the solar furnace was just
about to shut down. The theory also suggests that, at some periods in the past,
the earth was cooler than it is now; these would be the times when the solar fur-
nace was off, but was just about to start up for another cycle.
MAVERICK STARS
The stars in our galaxy do not all orbit in perfect unison around the center. On a
“local” scale, stars move in a random fashion with respect to each other. Besides
the sun, the nearest star is about 42,000,000,000,000 (4.2 × 10
13
) km, or
26,000,000,000,000 (2.6 × 10
13
) mi, distant. That is too far for its gravitational
field to affect our solar system. But suppose that, long ago, a maverick star came
close enough to perturb the orbits of the planets, including the earth?
A tiny change in the earth’s orbit might be enough to change the climate con-
siderably. One problem with the maverick star theory, however, is the fact that
the orbital change would be permanent, and the ice ages have always been tem-
porary. However, maverick-star events might be more common than we suspect.
Some astronomers have suggested that, scattered throughout the galaxy, there
are billions of tiny, dim stars that cannot be seen with optical telescopes. These
could, if passing near enough to the solar system, have a subtle effect on the
orbits of the planets.
CHAPTER 9 The Past and Future Climate
266