Let’s learn about ‘ghost particles’

Like tiny ghosts, super lightweight particles called neutrinos can slip through almost any matter

This is the inside of the Super-Kamiokande neutrino observatory in Japan. The detector is a cylinder 40 meters (131 feet) tall and filled with 50 million liters (13 million gallons) of water. The device detects incoming neutrinos using highly sensitive light sensors. These sensors record the tiny flashes of light caused by neutrinos interacting with molecules of water.

© 2020 Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo

Every second, trillions of “ghost particles” pass through your body. That may sound spooky, but fear not. These itty-bitty particles are neutrinos, and they cause no harm. They get their nickname from the fact that they hardly ever interact with other matter. In fact, they can zip through the entire Earth without a trace.

Neutrinos are so lightweight that for a long time, physicists thought the particles had no mass at all. Two researchers won the 2015 Nobel Prize in physics for proving they did. But the neutrino’s mass is tiny. Each one has less than a millionth of the mass of an electron. Neutrinos also have no electric charge, adding to their stealth.

As a result, neutrinos are very difficult to detect and study. To net neutrinos, researchers build huge detectors. Sensors in the machines spot the few, far-between flashes of light caused by rare neutrino interactions with nearby matter.

Despite being the introverts of the particle world, neutrinos are important for understanding the universe. Neutrinos are flung out by stellar explosions and flaring galaxies called blazars. Studying such neutrinos helps scientists better understand such high-energy phenomena. Neutrinos may also help solve one of the biggest questions in the universe: Why is the cosmos made up mostly of matter and not antimatter? 

Want to know more? We’ve got some stories to get you started:

Scientists traced an incoming neutrino back to its galactic birthplace The high-energy particle was born in a blazar 4 billion light-years away, scientists now report. (8/28/2018) Readability: 8.3

Particles that zip through matter snare Nobel Two scientists won the 2015 Nobel Prize in physics for their discovery that neutrinos, particles that can pass through almost all matter, have mass. (10/7/2015) Readability: 8.4

After 30 years, this supernova is still sharing secrets It’s been over 30 years since astronomers first witnessed the stellar explosion known as SN 1987A. Researchers are still learning from this cataclysmic phenomenon. (5/18/2017) Readability: 7.2

Neutrinos could help solve one of the biggest mysteries of the universe.

Explore more

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Long-sought subatomic particle ‘seen’ at last

First heavy element identified from a neutron-star collision

Stars made of antimatter could lurk in our galaxy

How ghostly neutrinos could explain the universe’s matter mystery (Science News)

High-energy neutrinos may come from black holes ripping apart stars (Science News)

Neutrinos hint the sun has more carbon and nitrogen than previously thought (Science News)

How neutrinos could ensure a submarine’s nuclear fuel isn’t weaponized (Science News)


Word find

The IceCube neutrino observatory is a huge detector at the South Pole. Built within a cubic kilometer (a quarter cubic mile) of ice, thousands of sensors measure the light produced when neutrinos from space slam into the ice. Check out the IceCube website for materials and instructions to build your own paper model of a neutrino detector, create IceCube-themed pumpkin carvings and more.

Maria Temming is the assistant editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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