astronomical time scale

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• Dynamical time scale — has two distinct meanings and usages, both related to astronomy: In one use, which occurs in stellar physics, the dynamical time scale is alternatively known as the freefall time scale, and is in general, the length of time over which changes in… …   Wikipedia

• Geologic time scale — This clock representation shows some of the major units of geological time and definitive events of Earth history. The Hadean eon represents the time before fossil record of life on Earth; its upper boundary is now regarded as 4.0 Ga.[1] Other… …   Wikipedia

• Time from NPL — Map showing the location of the Anthorn VLF transmitter within Cumbria …   Wikipedia

• Astronomical seeing — Schematic diagram illustrating how optical wavefronts from a distant star may be perturbed by a layer of turbulent mixing in the atmosphere. The vertical scale of the wavefronts plotted is highly exaggerated. Astronomical seeing refers to the… …   Wikipedia

• Time — This article is about the measurement. For the magazine, see Time (magazine). For other uses, see Time (disambiguation). The flow of sand in an hourglass can be used to keep track of elapsed time. It also concretely represents the present as… …   Wikipedia

• Time zone — Timezone and TimeZone redirect here. For other uses, see Time zone (disambiguation). Local time redirects here. For the mathematical concept, see Local time (mathematics). This article is about time zones in general. For a list of time zones by… …   Wikipedia

• Time standard — A time standard is any officially recognized specification for measuring time: either the rate at which time passes; or points in time; or both. For example, the standard for civil time specifies both time intervals and time of day. A time scale… …   Wikipedia

• Time dilation — This article is about a concept in physics. For the concept in sociology, see time displacement. In the theory of relativity, time dilation is an observed difference of elapsed time between two events as measured by observers either moving… …   Wikipedia

• Time signal — These automatic signal clocks were synchronized by telegraphy in 1905 before the widespread use of radio A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day. Contents 1 Audible… …   Wikipedia

• Astronomical distance — Astronomical distances are distances in outer space, occurring on a much larger scale than those on Earth. For instance, the distance to (Proxima Centauri), the closest star to our solar system, is about 40,000,000,000,000 kilometers.For this… …   Wikipedia

• ephemeris time — noun a) A former standard astronomical time scale intended to overcome the drawbacks of irregularly fluctuating mean solar time, superseded in the 1970s. b) A modern relativistic coordinate time scale …   Wiktionary