Neutrinos

Do you know what a neutrino is? This is Ernie the neutrino.

This is the highest energy neutrino ever observed, with an estimated energy of 1.14 PeV. It was detected by the IceCube Neutrino Observatory at the South Pole on Jan. 3, 2012.

From PHYS.org:

The IceCube Neutrino Observatory, a particle detector buried in the Antarctic ice, is a demonstration of the power of the human passion for discovery, where scientific ingenuity meets technological innovation. Today, nearly 25 years after the pioneering idea of detecting neutrinos in ice, the IceCube Collaboration announces the observation of 28 very high-energy particle events that constitute the first solid evidence for astrophysical neutrinos from cosmic accelerators.

From Wikipedia:

A neutrino (/nuːˈtriːnoʊ/ or /njuːˈtriːnoʊ/) is an electrically neutral, weakly interacting elementary subatomic particle[1] with half-integer spin. The neutrino (meaning "small neutral one" in Italian) is denoted by the Greek letter ν (nu). All evidence suggests that neutrinos have mass but that their mass is tiny even by the standards of subatomic particles. Their mass has never been measured accurately.

Neutrinos do not carry electric charge, which means that they are not affected by the electromagnetic forces that act on charged particles such as electrons and protons. Neutrinos are affected only by the weak sub-atomic force, of much shorter range than electromagnetism, and gravity, which is relatively weak on the subatomic scale. Therefore a typical neutrino passes through normal matter unimpeded.

Neutrinos are created as a result of certain types of radioactive decay, or nuclear reactions such as those that take place in the Sun, in nuclear reactors, or when cosmic rays hit atoms. There are three types, or "flavors", of neutrinos: electron neutrinos, muon neutrinos and tau neutrinos. Each type is associated with an antiparticle, called an "antineutrino", which also has neutral electric charge and half-integer spin. Whether or not the neutrino and its corresponding antineutrino are identical particles has not yet been resolved, even though the antineutrino has an opposite chirality to the neutrino.

Most neutrinos passing through the Earth emanate from the Sun. About 65 billion (6.5×1010) solar neutrinos per second pass through every square centimeter perpendicular to the direction of the Sun in the region of the Earth.