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  2. It is not just heavy metals which can be toxic; other metals (for example beryllium and lithium) can be toxic too. [267] Sleeping in a closed room with an electric fan running does not result in "fan death", as is widely believed in South Korea among older people. [268] [269] As of 2019 this belief was in decline. [270]

  3. List of astronomical instruments - Wikipedia

    en.wikipedia.org/wiki/List_of_astronomical...

    An astronomical instrument is a device for observing, measuring or recording astronomical data.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.

  4. Astronomical engineering - Wikipedia

    en.wikipedia.org/wiki/Astronomical_engineering

    Engineering on an astronomical scale, or astronomical engineering, i.e., engineering involving operations with whole astronomical objects (planets, stars, etc.), is a known theme in science fiction, as well as a matter of recent scientific research and exploratory engineering.

  5. Mathematical instrument - Wikipedia

    en.wikipedia.org/wiki/Mathematical_instrument

    Animation of construction of a pentagon using a compass and straightedge. A mathematical instrument is a tool or device used in the study or practice of mathematics.In geometry, construction of various proofs was done using only a compass and straightedge; arguments in these proofs relied only on idealized properties of these instruments and literal construction was regarded as only an ...

  6. Astronomy - Wikipedia

    en.wikipedia.org/wiki/Astronomy

    Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets.

  7. Hubble Space Telescope - Wikipedia

    en.wikipedia.org/wiki/Hubble_Space_Telescope

    Hubble was designed to accommodate regular servicing and equipment upgrades while in orbit. Instruments and limited life items were designed as orbital replacement units . [ 105 ] Five servicing missions (SM 1, 2, 3A, 3B, and 4) were flown by NASA Space Shuttles , the first in December 1993 and the last in May 2009. [ 106 ]

  8. Absolute space and time - Wikipedia

    en.wikipedia.org/wiki/Absolute_space_and_time

    Originally introduced by Sir Isaac Newton in Philosophiæ Naturalis Principia Mathematica, the concepts of absolute time and space provided a theoretical foundation that facilitated Newtonian mechanics. [3]

  9. Astrophysics - Wikipedia

    en.wikipedia.org/wiki/Astrophysics

    Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. [1] [2] As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space—what they are, rather than where they are", [3] which is studied ...