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A truly dark sky has a surface brightness of 2 × 10 −4 cd m −2 or 21.8 mag arcsec −2. [ 9 ] [ clarification needed ] The peak surface brightness of the central region of the Orion Nebula is about 17 Mag/arcsec 2 (about 14 milli nits ) and the outer bluish glow has a peak surface brightness of 21.3 Mag/arcsec 2 (about 0.27 millinits).
By the 2015 definition, 1 au of arc length subtends an angle of 1″ at the center of the circle of radius 1 pc. That is, 1 pc = 1 au/tan( 1″ ) ≈ 206,264.8 au by definition. [ 9 ] Converting from degree/minute/second units to radians ,
The siemens (symbol: S) is the unit of electric conductance, electric susceptance, and electric admittance in the International System of Units (SI). Conductance, susceptance, and admittance are the reciprocals of resistance, reactance, and impedance respectively; hence one siemens is equal to the reciprocal of one ohm (Ω −1) and is also referred to as the mho.
The lux is one lumen per square metre (lm/m 2), and the corresponding radiometric unit, which measures irradiance, is the watt per square metre (W/m 2). There is no single conversion factor between lux and W/m 2 ; there is a different conversion factor for every wavelength, and it is not possible to make a conversion unless one knows the ...
Meteorological data includes wind speeds which may be expressed as statute miles per hour, knots, or meters per second. Here are the conversion factors for those various expressions of wind speed: 1 m/s = 2.237 statute mile/h = 1.944 knots 1 knot = 1.151 statute mile/h = 0.514 m/s 1 statute mile/h = 0.869 knots = 0.447 m/s. Note:
Small granite pillars have failed under loads that averaged out to about 1.43 ⋅ 10 8 Newtons/meter 2 and this kind of rock has a sonic speed of about 5.6 ± 0.3 ⋅ 10 3 m/sec (stp), a density of about 2.7 g/cm 3 and specific heat ranging from about 0.2 to 0.3 cal/g °C through the temperature interval 100-1000 °C [Stowe pages 41 & 59 and ...
The particle densities tend to be in the range of 10 18 to 10 22 m −3 and the linear dimensions in the range of 0.1 to 10 m. The particle and energy confinement times may range from under a millisecond to over a second, but the configuration itself is often maintained through input of particles, energy, and current for times that are hundreds ...
The data below tabulates standard electrode potentials (E°), in volts relative to the standard hydrogen electrode (SHE), at: . Temperature 298.15 K (25.00 °C; 77.00 °F); ...