Glossary

Facula

A bright granular structure on the Sun's surface that is slightly hotter than the surrounding photosphere. It is always associated with a strong magnetic field. (faculae, pl.)

Micro-

A prefix meaning one-millionth

Milli-

A prefix meaning one-thousandth

Mya

Usually capitalized. An abbreviation for "million years ago."

REM

(Roentgen Equivalent Man)A unit for measuring absorbed doses of radiation, equivalent to one roentgen of x-rays or gamma rays.

Roentgen

(after Wilhelm Conrad Roentgen (1845 - 1923), a German physicist)A unit of radiation exposure equal to the quantity of ionizing radiation that will produce one electrostatic unit of electricity in one cubic centimeter of dry air at 0°C and standard atmospheric pressure.

Sunspot

A dark structure on the Sun's surface that is slightly cooler than the surrounding photosphere. A sunspot is always associated with a facula.

Theory

In science, a proposition that explains a wide variety of data, has myriad supporting data, and is essentially considered as fact.  No scientific theory is ever 100% certain.  Even such a well supported an accurate theory as quantum mechanics can be disproved by the validated result of one experiment. Usually when such data is found, a new theory is developed that is subsumes the old theory.  The old theory then will only have a limited range of applicability.  Einstein's general relativity theory is a good example.  This theory encompasses a much wider range of distances, masses, velocities, and energies than Newton's theory of gravity; but Newton's theory is still sufficient to put satellites into orbit and calculate the trajectory of a baseball.