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  2. Minute and second of arc - Wikipedia

    en.wikipedia.org/wiki/Minute_and_second_of_arc

    The metric system counterpart of the MOA is the milliradian (mrad or 'mil'), being equal to 1 ⁄ 1000 of the target range, laid out on a circle that has the observer as centre and the target range as radius. The number of milliradians on a full such circle therefore always is equal to 2 × π × 1000, regardless the target range. Therefore, 1 ...

  3. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    In the year −2000 (2001 BCE) the May maximum was +12 minutes and a couple seconds while the November maximum was just less than 10 minutes. The secular change is evident when one compares a current graph of the equation of time (see below) with one from 2000 years ago, e.g., one constructed from the data of Ptolemy.

  4. Degree (angle) - Wikipedia

    en.wikipedia.org/wiki/Degree_(angle)

    These considerations outweigh the convenient divisibility of the number 360. One complete turn (360°) is equal to 2 π radians, so 180° is equal to π radians, or equivalently, the degree is a mathematical constant: 1° = π ⁄ 180. One turn (corresponding to a cycle or revolution) is equal to 360°.

  5. Angle - Wikipedia

    en.wikipedia.org/wiki/Angle

    A similar calculation using the area of a circular sector θ = 2A/r 2 gives 1 radian as 1 m 2 /m 2 = 1. [35] The key fact is that the radian is a dimensionless unit equal to 1. In SI 2019, the SI radian is defined accordingly as 1 rad = 1. [36] It is a long-established practice in mathematics and across all areas of science to make use of rad ...

  6. Radian - Wikipedia

    en.wikipedia.org/wiki/Radian

    A similar calculation using the area of a circular sector θ = 2A/r 2 gives 1 radian as 1 m 2 /m 2 = 1. [10] The key fact is that the radian is a dimensionless unit equal to 1. In SI 2019, the SI radian is defined accordingly as 1 rad = 1. [11] It is a long-established practice in mathematics and across all areas of science to make use of rad ...

  7. 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 ...

  8. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    Ten seconds (one sixth of a minute) minute: 60 s: hectosecond: 100 s: milliday: 1/1000 d (0.001 d) 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]

  9. Clock angle problem - Wikipedia

    en.wikipedia.org/wiki/Clock_angle_problem

    The angle is typically measured in degrees from the mark of number 12 clockwise. The time is usually based on a 12-hour clock. A method to solve such problems is to consider the rate of change of the angle in degrees per minute. The hour hand of a normal 12-hour analogue clock turns 360° in 12 hours (720 minutes) or 0.5° per minute.