'Ghost particles' can zoom through you without a trace. Scientists are getting to the bottom of this cosmic mystery

A blazar accelerates protons (the yellow p) to the energy levels of cosmic rays, initiating a complex quantum cascade that also releases gamma rays (magenta) and neutrinos (blue), which follow straight paths through space. The coupled detection of these two particles enabled astronomers to identify the blazar as a source of cosmic rays.

Imagine a particle so ghostly that over 100 trillion of them could pass through you every single second without you noticing anything at all. Spooky, right? Well, believe it or not, these particles, called "neutrinos," not only exist, but they are so abundant that they are the second most common particle in the universe (after photons, the particles that make up light).

So, you might not get visited by a phantom this Halloween, but you'll definitely encounter plenty of cosmic ghost neutrinos, yet you won't notice a single thing. In fact, you're encountering them right now.