hour-angle scale
1hour circle — Astron. a great circle on the celestial sphere passing through the celestial poles and containing a point on the celestial sphere, as a star or the vernal equinox. Also called circle of declination. [1665 75] * * * ▪ astronomy in astronomy …
2Right angle — In geometry and trigonometry, a right angle is an angle of 90 degrees, corresponding to a quarter turn (that is, a quarter of a full circle). It can be defined as the angle such that twice that angle amounts to a half turn, or 180° [Lindahl, G.… …
3Full Scale 30- by 60-Foot Tunnel — Infobox nrhp name = Full Scale Wind Tunnel nrhp type = nhl caption = Open test section of the Full Scale Wind Tunnel lat degrees = 37 lat minutes = 4 lat seconds = 51 lat direction = N long degrees = 76 long minutes = 20 long seconds = 30 long… …
4Solar time — On a prograde planet like the Earth, the sidereal day is shorter than the solar day. At time 1, the Sun and a certain distant …
5Equinox — This article is about the astronomical event when the sun is at zenith over the Equator. For other uses, see Equinox (disambiguation). For the same event happening on other planets and setting up a celestial coordinate system, see Equinox… …
6Tide — This article is about tides in the Earth s oceans. For other uses, see Tide (disambiguation). Tidal redirects here. For other uses, see Tidal (disambiguation). High Tide redirects here. For other uses, see High Tide (disambiguation) …
7List of selected stars for navigation — The selected stars for navigation are often used for sextant observations. Fifty eight selected navigational stars are given a special status in the field of celestial navigation. Of the approximately 6,000 stars visible to the naked eye under… …
8Su Song — 蘇頌 (Sū Sòng) Born 1020 near Quanzhou Died 1101 (aged 80–81) Nationality Chinese …
9Celestial coordinate system — For other uses of Celestial , see Celestial (disambiguation). Orientation of Astronomical Coordinates Orientation of the galactic, ecliptic and equatorial coordinate systems, projected on the celestial sphere, showing the galactic equator (black) …
10Astrocompass — An astrocompass is a navigational tool for determining the direction of north through the positions of various astronomical bodies.There are certain circumstances when magnetic compasses and gyrocompasses are unreliable. The most obvious is in… …
