n
(usually with the) The apparently open space above the ground which this substance fills, (historical) formerly thought to be limited by the firmament but (meteorology) now considered to be surrounded by the near vacuum of outer space.
n
A faint illumination in the sky due to photochemical luminescence in the upper atmosphere, now rarely observed by earthbound humans without the assistance of instruments.
adj
(astronomy, now only in compounds) Pertaining to the celestial north pole, or to the pole star.
n
Alternative spelling of Arctic Circle [The parallel of latitude that runs 66° 33′ 39″ north of the Equator, which marks approximately the southernmost place in the Northern Hemisphere where the sun does not set on the summer solstice and does not rise on the winter solstice.]
n
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.
n
The aurora of the northern hemisphere.
n
(Antarctica) Insomnia due to the lengths of the days and nights in the polar regions.
n
A set of currents that flow along geomagnetic field lines connecting the Earth's magnetosphere to the Earth's high-latitude ionosphere.
n
A structure that is embedded in a uniformly bright aurora, where its optical emission is significantly reduced, presenting as either patches or arcs that mainly drift eastwards.
n
(astronomy) Alternative letter-case form of earthshine [(astronomy) Reflected earthlight visible on the Moon's night side.]
n
(astronomy, geology) In planetary geology, any of the river-like features on Saturn's moon Titan.
adj
Pertaining to or caused by both the moon and the sun.
n
(martial arts) A striking weapon resembling a track and field hammer consisting of a weight swung at the end of a cable or chain.
n
(nautical) A bioluminescent phenomenon observable on moonless nights, caused by luminous plankton and bacteria, where the sea becomes milky white with a slight glow allowing one to see one's ship. The sea shines from horizon to horizon like a field of fresh snow (when only the surface layers shine) or a cloud (when deeper layers also shine). The phenomenon occurs most often in the Indian Ocean and off Indonesia; and does not require disruption to start shining.
n
(Australia) An unexplained light reportedly appearing in the sky in remote parts of Australia, especially northwest Queensland, possibly caused by reflections of distant light in the dry air conditions.
n
The temperate zone between the Arctic Circle and the Tropic of Cancer.
n
(dated) Synonym of aurora borealis
n
The aurora of the northern hemisphere.
n
A bluish shade of black.
n
A bright, circular spot, sometimes seen on a lunar halo, caused by refraction through ice crystals.
n
The aurora borealis or aurora australis.
n
(astronomy, meteorology) an upper atmospheric optical phenomena associated with thunderstorms, large but weak luminous flashes that appear directly above an active thunderstorm system and are coincident with powerful positive cloud-to-ground lightning strokes
n
A principle in international law where international boundaries are extended over sea areas in the Arctic towards the North Pole following meridians (lines of longitude). The same principle is used over land in the Antarctic to the South Pole.
adj
Of or relating to the Moon.
adj
Pertaining to the Sun (the star Sol).
adj
Alternative spelling of solar-type [(astronomy, of a star) Having similar characteristics to those of the Sun.]
adj
(obsolete) Pertaining to the sun; solar.
n
The aurora of the southern hemisphere.
v
To look at the stars at night.
n
Synonym of sidereal month
n
An aurora-like light found in southern Canada (consistently lower latitude, unlike the aurora borealis which is generally high latitude), composed of a glowing purple ribbon of light, with green spikes coming off obliquely parallel to each other, moving at about 6.5 km/s East to West. Presumably occurs in the southern hemisphere as well.
n
A stream or column of light shooting upward from the horizon, constituting one of the forms of the aurora borealis.
adj
Of or pertaining to the style of a sundial.
n
The ascription of the greater inequalities in the earth's surface to atmospheric influences.
adj
directly beneath the sun
n
Either of two bright spots, caused by the refraction of sunlight through ice crystals, sometimes seen on the parhelic circle.
n
(countable) A figure or shape showing rays radiating from a central point.
adj
(astronomy) Resembling the Sun.
n
A weak aurora above the tropics
v
To make a wish on seeing a shooting star
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