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An astronomical instrument is a device for observing, measuring, or recording astronomical data. [ citation needed ] They are used in the scientific field of astronomy , a natural science that studies celestial objects and the phenomena that occur in the cosmos, with the object of explaining their origin and evolution over time.
Actual sunset: Two minutes before the Sun disappears below the horizon. Sunset (or sundown) is the disappearance of the Sun at the end of the Sun path, below the horizon of the Earth (or any other astronomical object in the Solar System) due to its rotation.
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a ...
A number of instruments have been invented, designed, and made, that make sound from matter in its liquid state. This class of instruments is called hydraulophones . Hydraulophones use an incompressible fluid, such as water, as the initial sound-producing medium, and they may also use the hydraulic fluid as a user-interface.
The history of astronomy focuses on the contributions civilizations have made to further their understanding of the universe beyond earth's atmosphere. [1] Astronomy is one of the oldest natural sciences , achieving a high level of success in the second half of the first millennium.
A second gravitational wave was detected on 26 December 2015 and additional observations should continue but gravitational waves require extremely sensitive instruments. [ 62 ] [ 63 ] The combination of observations made using electromagnetic radiation, neutrinos or gravitational waves and other complementary information, is known as multi ...
Military instruments as a class draw on most of the categories of instrument described throughout this article, such as navigation, astronomy, optics, and imaging, and the kinetics of moving objects. Common abstract themes that unite military instruments are seeing into the distance, seeing in the dark, knowing an object's geographic location ...
Also actiniform. Describing a collection of low-lying, radially structured clouds with distinct shapes (resembling leaves or wheels in satellite imagery), and typically organized in extensive mesoscale fields over marine environments. They are closely related to and sometimes considered a variant of stratocumulus clouds. actinometer A scientific instrument used to measure the heating power of ...