Solar Neutrino | Universe Today

Written by Fraser Cain

I'm going to tell you something, but I don't want you to panic. Okay? Right now, every second, there are 65 billion particles from the Sun passing through every centimeter of your body. Don't worry, they're totally harmless. In fact, until the middle of the 20th century, nobody even know they existed. These particles are solar neutrinos, and they're one of the most interesting discoveries made in modern physics.

As you probably know, the Sun generates all its energy through solar fusion. Four protons are converted through a series of steps into a helium atom. The final configuration of helium atoms requires less energy than the initial 4 protons, and so energy is released from each fusion reaction. In addition to this energy and helium, two of the protons have to be converted into neutrons. And each conversion releases one electron neutrino.

The moment it's created, a solar neutrino passes quickly through the Sun and out into space. In fact, neutrinos can pass right through the Earth without even noticing. It's thought that a neutrino can almost get through a light-year's worth of solid lead before finally interacting with another particle. This is why you can't even feel them. They're going right through your body as if you weren't even there.

The only way to detect neutrinos is with a large volume of water surrounded by sensors. Even through neutrinos interact rarely, they do occasionally collide with the nucleus of another particle, annihilate, and release a cascade of particles that can be detected. By detecting this cascade, scientists can trace back the fact that a neutrino was responsible.

Here's an article about how neutrinos might be used to probe the Earth's interior, and another article about how scientists can fire a focused beam of neutrinos.

Here's another article about solar neutrinos, and a cool picture of a neutrino detector from Astronomy Picture of the Day.

We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.

Filed under: Astronomy