The missing neutrino mystery began in 1856 when German scientist Hermann von Helmholtz theorized that the Sun produces its energy because it is in a state of gravitational collapse. He calculated that if the energy output were due to a gravitational collapse then the heat would be near the 22 million degrees Farenheit range. Today scientist know that this is an amazingly accurate figure and very close to their own.

According to the Helmholtz theory of gravitational collapse if the Sun did work in this manner that meant that it could not have been in existence for more than 22 million years. This theory was the pervading thought until the 1920s when some scientists suggested that the Sun worked by nuclear fusion.

"It seems agreed that the numbers of detectable neutrinos emitted by the Sun are smaller than they should be, but people are still vainly searching for an explanation."

Which one is correct? The most commonly accepted theory today is that the Sun operates through fusion. However, this theory leaves many unanswered questions and has given rise to new study of the Sun to determine which is correct.

For the nuclear fusion theory to be correct the Earth should be receiving a form of energy from the Sun called neutrinos. They are very minute particles of energy and are very difficult to detect. They are what Davis was looking for in the 1970s with his neutrino experiments. Further studies and experiments have been done looking for neutrinos; a joint Soviet-US team attempting to measure the neutrinos again came up short of the number expected. The Japanese have built the most advanced device yet to measure for neutrinos in a mine surrounded by water to minimize outside pollution of the results but have not found the number of neutrinos that should be bombarding the Earth for the fusion theory to be correct.

There are some possible explanations for this. One is that the neutrinos change to another form during their 8 minute journey from the Sun. The other is that the Sun does not operate by nuclear fusion but by gravitational collapse as suggested by Helmholtz.

In 1979 John Eddy of the Center for Astrophysics at the High Altitude Observatory at Boulder, Colorado stunned many in the scientific community when he stated at a conference of the American Astronomical Society that:

"I suspect... that the sun is 4.5 billion years old. However, given some new and unexpected results to the contrary and some time for frantic readjustment, I suspect that we could live with Bishop Ussher's figure for the age of the earth and sun (approximately 6,000 years). I don't think we have much in the way of observational evidence in astronomy to conflict with that."

Before the 1979 conference Eddy had been at the Greenwich Observatory in England studying Sunspot activity. The observatory was using their telescope to measure the Sun's passage across the sky as had been done since the early 1800s. Daily photographs and measurements were taken of the Sun. Eddy began comparing the horizontal and vertical measurements of the Sun from these photographs and realized that the size of the Sun was not constant.

He later discovered that the US Naval Observatory in Washington had been keeping similar records and they had come to the same conclusion. According to both of them the Sun was definitely shrinking. In fact they calculate shrinkage to be nearly 10 miles per year or almost 6 feet per hour.

They felt that this couldn't be possible so they went back to records that existed during the lifetime of Galileo to compare. They found that observation of an eclipse in 1567 showed that the Sun was not covered completely by the moon and was therefore larger.

Other scientists had joined the search for the truth, such as Sophia and O'Keefe of NASA's Goddard Space Flight Center in Maryland. They reported in 1979 that they too had found evidence for a decrease in the Sun's diameter. Only a week after John Eddy made his speech in 1979 they reported in "Science" that they had found evidence for a slow systematic decrease in the Sun's diameter. Their rate of decrease was less but a decrease nonetheless.

What does all of this mean? It may mean that the scientific community may have to rethink their theories on how the Sun works or it may mean that we need to learn more about neutrinos and whether or not they can change into other particles that we are not detecting.

Some scientists believe that the core of the Sun may be shrinking but that the outer layers are involved in an expanding and contracting phase. If this proves to be the case then the neutrino mystery will be solved.