Neutrinos from the Sun

Missing neutrinos, and shrinking suns

Many Creationist authors (such as Taylor) have mentioned the "missing neutrino" problem. This was a real physics problem as recently as 1998. From mathematical models of the Sun's interior, scientists calculated how many neutrinos should be given off. And, the people running neutrino detectors were not seeing a big enough count. It was puzzling.

Of course, the solar modellers could have solved this by just using a temperature (at the center of the Sun) which was 10% lower. But the solar modellers said that the uncertainty in their models was much less than 10%.

This problem was completely solved in the years 2001-2004. It is now known that neutrinos "oscillate" between three different forms. Since our major neutrino detectors are only sensitive to some of those forms, they counted only some of the solar neutrinos. For details see this FAQ.

Old claims that the number of solar neutrinos detected "may be zero" were completely wrong. Some neutrino detectors can measure the direction that a neutrino came from. And, they measure it accurately enough for us to assemble this "neutrino portrait" of the Sun:

The Sun as seen by neutrino detectors

(Of course, it's not a normal picture, because the neutrinos didn't arrive all at once at a camera. They arrived one by one, across years, and a computer program assembled this false-color image in 1998.)

The solar models don't just say how many neutrinos will come off. They also state what energy the neutrinos will have, and in fact, we detect solar neutrinos that have that energy.

There is a Creationist theory that the Sun doesn't get its heat from nuclear fusion. Instead, the "shrinking Sun" theory says that the Sun is very young, and the heat is generated by shrinking. (That is, the Sun is heated by gravitational energy.) But without nuclear fusion, there wouldn't be neutrinos, so this "neutrino portrait" completely disproves the theory. And, as it turns out, the Sun's size has been measured, and it isn't shrinking.

Last modified: 25 June 2006

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