北极光

[电] 北极光

[ noun ]
the aurora of the northern hemisphere
<noun.phenomenon>

Aurora \Au*ro"ra\, n.; pl. E. {Auroras}, L. (rarely used)
{Auror[ae]}. [L. aurora, for ausosa, akin to Gr. ?, ?, dawn,
Skr. ushas, and E. east.]
1. The rising light of the morning; the dawn of day; the
redness of the sky just before the sun rises.

2. The rise, dawn, or beginning. --Hawthorne.

3. (Class. Myth.) The Roman personification of the dawn of
day; the goddess of the morning. The poets represented her
a rising out of the ocean, in a chariot, with rosy fingers
dropping gentle dew.

4. (Bot.) A species of crowfoot. --Johnson.

5. The aurora borealis or aurora australis (northern or
southern lights).

{Aurora borealis}, i. e., northern daybreak; popularly called
northern lights. A luminous meteoric phenomenon, visible
only at night, and supposed to be of electrical origin.
This species of light usually appears in streams,
ascending toward the zenith from a dusky line or bank, a
few degrees above the northern horizon; when reaching
south beyond the zenith, it forms what is called the
corona, about a spot in the heavens toward which the
dipping needle points. Occasionally the aurora appears as
an arch of light across the heavens from east to west.
Sometimes it assumes a wavy appearance, and the streams of
light are then called merry dancers. They assume a variety
of colors, from a pale red or yellow to a deep red or
blood color. The

{Aurora australis}is a corresponding phenomenon in the
southern hemisphere, the streams of light ascending in the
same manner from near the southern horizon.