See also:

• AURORA
• AURORA (perhaps through a form ausosa from Sansk. ush, to burn ; the common idea of " brightness " suggests a connexion with aurum, gold)

AURORA POLARIS (Aurora Borealis and Australis, Polar See also:

• LIGHT

Light, See also:

• NORTHERN

Northern See also:

• LIGHTS, CEREMONIAL USE OF

Lights)  , a natural phenomenon which occurs in many forms, some of See also:

• GREAT

great beauty . r . Forms.—Various schemes of See also:

• CLASSIFICATION (Lat. classis, a class, probably from the root cal-, cla-, as in Gr. icaMce, clamor)

classification have been proposed, but none has met with universal See also:

• ACCEPTANCE (Lat. acceptare, frequentative form of accipere, to receive)

acceptance; the following are at least the See also:

• PRINCIPAL

principal types . (1) Arcs . These most commonly resemble segments of circles, but are not in-frequently elliptical or irregular in outline . The ends of arcs frequently extend to the See also:

• HORIZON (Gr. 6pfTwv, dividing)

horizon, but often one or both ends stop See also:

• SHORT, FRANCIS JOB (1857– )

short of this . Several arcs may be visible at the same See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time . Usually the under or See also:

• CONCAVE

concave edge of the arc is the more clearly defined, and adjacent to it the See also:

• SKY (M. Eng. skie, cloud; O. Eng. skua, shade; connected with an Indo-European root sku, cover, whence " scum," Lat. obscurus, dark, &c.)

sky often seems darker than elsewhere . It is rather a disputed point whether this dark segment—through which starlight has been seen to pass—represents a real atmospheric See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition or is merely a contrast effect . (2) Bands . These may be nearly straight and See also:

• REGULAR

regular in outline, as if broken portions of arcs; frequently they are ribbon-like See also:

• SERPENTINE

serpentine forms showing numerous sinuosities . (3) Rays .

Frequently an arc or See also:

• BAND

band is visibly composed of innumerable short rays separated by distinctly less luminous intervals . These rays are more or less perpendicular to the arc or band; sometimes they are very approximately parallel to one another, on other occasions they converge towards a point . Longer rays often show an See also:

• INDEPENDENT

independent existence . Not in-frequently rays extend from the upper edge of an arc towards the See also:

• ZENITH (from the Arabic)

zenith . Combinations of rays sometimes resemble a luminous See also:

• FAN (Lat. vannus; Fr. eventail)

fan, or a See also:

• SERIES (a Latin word from serere, to join)

series of fans, or See also:

• PART

part of a hollow luminous See also:

• CYLINDER (Gr. KvAwSpos, from KvXivaety, to roll)

cylinder . Rays often alter suddenly in length, seeming to stretch down towards the horizon or See also:

• MOUNT, WILLIAM SIDNEY (1807-1868)

mount towards the zenith . This accounts for the description of See also:

• AURORA
• AURORA (perhaps through a form ausosa from Sansk. ush, to burn ; the common idea of " brightness " suggests a connexion with aurum, gold)

aurora as " Merry Dancers." (4) Curtains or Draperies . This See also:

• FORM (Lat. forma)

form is rare except in See also:

• ARCTIC (Gr. "ApKroc, the Bear, the northern constellation of Ursa Major)

Arctic regions, where it is sometimes fairly frequent . It is one of the most imposing forms . As a See also:

• RULE

rule the higher portion is visibly made up of rays, the See also:

• LIGHT

light tending to become more continuous towards the See also:

• LOWER

lower edge; the See also:

• COMBINATION (Lat. combinare, to combine)

combination suggests a connected whole, like a See also:

• CURTAIN

curtain whose alternate portions are in light and shade .