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  2. Astronomical coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Astronomical_coordinate...

    Angles in the hours ( h), minutes ( m), and seconds ( s) of time measure must be converted to decimal degrees or radians before calculations are performed. 1 h = 15°; 1 m = 15′; 1 s = 15″ Angles greater than 360° (2 π ) or less than 0° may need to be reduced to the range 0°−360° (0–2 π ) depending upon the particular calculating ...

  3. Parsec - Wikipedia

    en.wikipedia.org/wiki/Parsec

    Imagining an elongated right triangle in space, where the shorter leg measures one au (astronomical unit, the average Earth–Sun distance) and the subtended angle of the vertex opposite that leg measures one arcsecond (1 ⁄ 3600 of a degree), the parsec is defined as the length of the adjacent leg.

  4. Angular diameter - Wikipedia

    en.wikipedia.org/wiki/Angular_diameter

    (For example, the three stars of the Belt cover about 4.5° of angular size.) However, much finer units are needed to measure the angular sizes of galaxies, nebulae, or other objects of the night sky. Degrees, therefore, are subdivided as follows: 360 degrees (°) in a full circle; 60 arc-minutes (′) in one degree; 60 arc-seconds (″) in one ...

  5. Right ascension - Wikipedia

    en.wikipedia.org/wiki/Right_ascension

    Since a complete circle contains 24 h of right ascension or 360° (degrees of arc), ⁠ 1 / 24 ⁠ of a circle is measured as 1 h of right ascension, or 15°; ⁠ 1 / 1440 ⁠ of a circle is measured as 1 m of right ascension, or 15 minutes of arc (also written as 15′); and ⁠ 1 / 86400 ⁠ of a circle contains 1 s of right ascension, or 15 ...

  6. Planck units - Wikipedia

    en.wikipedia.org/wiki/Planck_units

    In SI units, the values of c, h, e and k B are exact and the values of ε 0 and G in SI units respectively have relative uncertainties of 1.6 × 10 −10 ‍ [16] and 2.2 × 10 −5. [17] Hence, the uncertainties in the SI values of the Planck units derive almost entirely from uncertainty in the SI value of G.

  7. This Radio Pulse From Space Lasts Three Seconds ... - AOL

    www.aol.com/lifestyle/radio-pulse-space-lasts...

    The pulse lasts 1,000 times longer than other neutron star signals. Researchers guess it probably originates from the star’s powerful magnetic field.

  8. Spacetime - Wikipedia

    en.wikipedia.org/wiki/Spacetime

    The constant , the speed of light, converts time units (like seconds) into space units (like meters). The squared interval Δ s 2 {\displaystyle \Delta s^{2}} is a measure of separation between events A and B that are time separated and in addition space separated either because there are two separate objects undergoing events, or because a ...

  9. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    1.44 minutes, or 86.4 seconds. Also marketed as a ".beat" by the Swatch corporation. moment: 1/40 solar hour (90 s on average) Medieval unit of time used by astronomers to compute astronomical movements, length varies with the season. [4] Also colloquially refers to a brief period of time. centiday 0.01 d (1 % of a day) 14.4 minutes, or 864 ...