CHANCE OF STORMS: NOAA forecasters estimate a 65% chance of polar geomagnetic storms on March 15th when a CME might deliver a glancing blow to Earth's magnetic field. The CME was launched by a filament of solar magnetism that erupted on March 12th. High-latitude sky watchers should be alert for auroras when the cloud arrives.
c.1400, from Medieval Greek omega, from classical Greek o mega "big 'o' " (in contrast to o micron "little 'o' "); so called because the vowel was long in ancient Greek. From mega (seemega-). The final letter of the Greek alphabet, hence used figuratively for "the last, final" of anything (cf. Rev. i:8),