The IceCube lab is illuminated by moonlight in an undated photo.
In fact, neutrinos, a type of elementary particle with no electric charge and very little mass, are all around us. Many trillions of them, produced in the sun’s nuclear core, zip right through our bodies every second of day and night. Luckily, they do no harm and leave no trace. That’s because neutrinos hardly ever interact with other particles: A typical neutrino can traverse the Earth, or even a light-year’s worth of lead, without bumping into an atom. Their severe reluctance to mingle makes neutrinos hard to pin down, so scientists have to build mammoth (and expensive) detectors like IceCube to trap just a few.