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MUL.APIN (𒀯 𒀳) is the conventional title given to a Babylonian compendium that deals with many diverse aspects of Babylonian astronomy and astrology.It is in the tradition of earlier star catalogues, the so-called Three Stars Each lists, but represents an expanded version based on more accurate observation, likely compiled around 1000 BCE. [1]
The enumeration of stars in the Three Stars Each catalogues includes 36 stars, three for each month. The determiner glyph for "constellation" or "star" in these lists is MUL ( 𒀯 ), originally a pictograph of three stars, as it were a triplet of AN signs; e. g. the Pleiades are referred to as a "star cluster" or "star of stars" in the lists ...
The Guide Star Catalog is an online catalogue of stars produced for the purpose of accurately positioning and identifying stars satisfactory for use as guide stars by the Hubble Space Telescope program. The first version of the catalogue was produced in the late 1980s by digitizing photographic plates and contained about 20 million stars, out ...
Each night the planet appeared to lag a little behind the stars, in what is called prograde motion. Near opposition, the planet would appear to reverse and move through the night sky faster than the stars for a time in retrograde motion before reversing again and resuming prograde. Epicyclic theory, in part, sought to explain this behavior.
The internal structure of a main sequence star depends upon the mass of the star. In stars with masses of 0.3–1.5 solar masses (M ☉), including the Sun, hydrogen-to-helium fusion occurs primarily via proton–proton chains, which do not establish a steep temperature gradient. Thus, radiation dominates in the inner portion of solar mass stars.
Russell's early (1913) versions of the diagram included Maury's giant stars identified by Hertzsprung, those nearby stars with parallaxes measured at the time, stars from the Hyades (a nearby open cluster), and several moving groups, for which the moving cluster method could be used to derive distances and thereby obtain absolute magnitudes for ...
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Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution