The Handy Astronomy Answer Book by Charles Liu PhD

Author:Charles Liu, PhD
Language: eng
Format: epub
Publisher: Visible Ink Press
Published: 2014-04-14T04:00:00+00:00

The first two Van Allen belts were discovered encircling Earth in 1958, and a third was found by NASA’s Van Allen Probes in 2012. (NASA/Van Allen Probes/Goddard Space Flight Center)

Do other objects in the solar system have Van Allen belts?

Yes. All the gas giant planets are thought to have such belts, and in Jupiter’s magnetic field such belts have been observationally confirmed.

NEUTRINOS

What is a neutrino?

A neutrino is a tiny subatomic particle that is far smaller than an atomic nucleus; it has no electrical charge and a tiny mass. (Electrons are many thousands of times more massive than neutrinos, and protons and neutrons are many millions of times more massive.) Neutrinos are so tiny and ghostly that they almost always pass through any substance in the universe without any interference or reaction.

How was the existence of neutrinos proved?

The existence of neutrinos was first suggested in 1930 by the Austrian physicist Wolfgang Pauli (1900–1958). He noticed that in a type of radioactive process called beta decay, the range of the total energy given off in observations was greater than expected in theoretical predictions. He reasoned that there must be another type of particle present to account for, and carry away, some of this energy. Since the amounts of energy were so tiny, the hypothetical particle must be very tiny as well and have no electric charge. A few years later, the Italian physicist Enrico Fermi (1901–1954) coined the name “neutrino” for this enigmatic particle. The existence of neutrinos was not experimentally confirmed, however, until 1956, when American physicists Clyde L. Cowan, Jr. (1919–1974) and Frederick Reines (1918–1998) de-170 tected neutrinos at a special nuclear facility in Savannah River, South Carolina.

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