A fascinating observation has been tentatively announced by scientists using the Japanese SuperKamiokande neutrino detector. After analyzing 18 years of data it appears that neutrinos generated by fusion in the sun's core ‘flip' flavors when detected on the night-side of Earth.
ANALYSIS: Neutrino Halo May Change Supernova ‘Flavor'
Neutrinos are the chargeless ‘ghosts' of the quantum world. They have very little mass and travel near the speed of light. They are so weakly interacting with normal matter that they can blast through our entire planet, from one side to the other, without hitting a thing. The only force they interact with is the weak force.
Although they may seem impossible to detect, physicists have devised a means to snare stealthy neutrinos should they score a direct hit with terrestrial matter.
In the case of the SuperKamiokande detector, a vast cavern under a mountain 300 kilometers (190 miles) from Tokyo has been filled with 50,000 tons of ultra-pure water and thousands of detectors cover the cavern's walls. Occasionally, should a direct collision between a neutrino and water molecule occur, high-energy electrons or muons are generated. These collision particles generate Cerenkov radiation, causing a brief flash that can be measured. If you have a big enough vat of water, it's statistically likely that enough neutrino collisions can be spotted to create a kind of "neutrino telescope" (though, technically, it's more of a particle detector than a telescope).