right ascension of the mean sun
91Orbital period — For the music album, see Orbital Period (album). The orbital period is the time taken for a given object to make one complete orbit about another object. When mentioned without further qualification in astronomy this refers to the sidereal period …
92star cluster — Astron. a number of stars of common origin held together as a group by gravitational attraction. Cf. globular cluster, open cluster, stellar association. * * * ▪ astronomy Introduction either of two general types of stellar assemblages held… …
93Mesopotamia, history of — ▪ historical region, Asia Introduction history of the region in southwestern Asia where the world s earliest civilization developed. The name comes from a Greek word meaning “between rivers,” referring to the land between the Tigris and… …
94Pytheas — of Massilia (Ancient Greek Πυθέας ὁ Μασσαλιώτης), 4th century BC, was a Greek geographer and explorer from the Greek colony Massilia (today Marseille, France). He made a voyage of exploration to northwestern Europe possibly no earlier than around …
95Thunderstorm — Electrical storm redirects here. For other uses, see Electrical storm (disambiguation). A typical thunderstorm A thunderstorm, also known as an electrical storm, a lightning storm, thundershower or simply a storm is a form of weather… …
96Ephemeris — An ephemeris (plural: ephemerides; from the Greek word ἐφήμερος ephemeros daily ) is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds are used for astronomy and astrology.… …
97243 Ida — Galileo image of 243 Ida. The tiny dot to the right is its moon, Dactyl. Discovery[1] and designation …
98San Diego — This article is about the city in California. For the metropolitan area, see San Diego metropolitan area. For other meanings of San Diego , see San Diego (disambiguation). San Diego   City   City of San Diego …
99Celestial 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) …
100Gliese 581 — Gliese 581 The star Gliese 581. Digitized Sky Survey photo. Observation data Epoch J2000.0      Equinox J2000.0 (ICRS) …
