A phenomenon consisting of luminous colorful arcs, rays, and streamers that appear in the Earth's upper atmosphere during the night with the greatest frequency in the northern and southern polar magnetic zones. This → non-thermal radiation is caused by the emission of light from atoms excited by electrons accelerated along the planet's magnetic field lines at the magnetic poles. Fluorescent emission from atomic oxygen at 5557 Å results in a greenish glow, and there is a weaker effect from the red line at 6300 Å. Blue and purple colors are emitted by atomic and molecular nitrogen.
L. Aurora, the Roman goddess of dawn, akin to Av. uš-, ušah- "dawn," Skt. usas-, usah- "dawn," Gk. eos "dawn," Lith. ausra "dawn," O.E. east "east," PIE *ausus- "dawn," from *aus- "to shine."
Ušé, from Av. uš-, ušah-, as above.
Fr.: aurore australe
The aurora in the Southern hemisphere, also called as Southern Lights.
Fr.: aurore boréale
The aurora in the Northern hemisphere, also called as Northern Lights.
Pertaining to the → aurora phenomenon.
Fr.: émission aurorale
Fr.: raie aurorale
1) A prominent → forbidden line in the spectra of
the aurora at wavelengths of 5577 and 6300 Å giving the aurora its
characteristic green and red colors.
Both are emitted by atomic oxygen, the former in its transition from the
second lowest excited electronic state (1S) to the lowest
excited electronic state (1D), the latter in its transition
from the lowest excited electronic state (1D) to the atomic
ground state (3P).
Fr.: zone aurorale
A roughly circular band around either geomagnetic pole above which there is a maximum of auroral activity. It lies about 10 to 15° of geomagnetic latitude from the geomagnetic poles.
Fr.: raie transaurorale
A forbidden line emitted by interstellar ionized gas by several atomic species (O, O+, O++, N+, S++, etc.) corresponding to the transition from the electronic state 1S to 3P. Examples are the ultraviolet line of the doubly ionized oxygen [O III] at 2321 A and [N II] 3063 A. → auroral line; → forbidden line; → nebular line.