An atmospheric phenomenon created by charged particles from the sun striking the upper atmosphere, creating coloured lights in the sky. It is usually named australis or borealis based on whether it is in the Southern or Northern Hemisphere respectively.

October 14th, 2026

In full celestial meridian: a great circle passing through the poles of the celestial sphere and the zenith for a particular point on the Earth's surface. [from 14th c.]

October 13th, 2026

A separation or division into two; a distinction that results in such a division.

October 12th, 2026

(physiology) Denoting or relating to scotopia (“vision of an eye under dim or low-light conditions”), believed to involve chiefly the rod cells of the retina; also, adapted to vision under low-light conditions.

October 11th, 2026