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The solar constant includes radiation over the entire electromagnetic spectrum. It is measured by satellite as being 1.361 kilo watts per square meter (kW/m 2) at solar minimum (the time in the 11-year solar cycle when the number of sunspots is minimal) and approximately 0.1% greater (roughly 1.362 kW/m 2) at solar maximum. [1]
Solar radiation pressure on objects near the Earth may be calculated using the Sun's irradiance at 1 AU, known as the solar constant, or G SC, whose value is set at 1361 W/m 2 as of 2011. [17] All stars have a spectral energy distribution that depends on their surface temperature. The distribution is approximately that of black-body radiation.
The solar flux unit (sfu) is a convenient measure of spectral flux density often used in solar radio observations, such as the F10.7 solar activity index: [1]. 1 sfu = 10 4 Jy = 10 −22 W⋅m −2 ⋅Hz −1 = 10 −19 erg⋅s −1 ⋅cm −2 ⋅Hz −1.
The relative spectral flux density is also useful if we wish to compare a source's flux density at one wavelength with the same source's flux density at another wavelength; for example, if we wish to demonstrate how the Sun's spectrum peaks in the visible part of the EM spectrum, a graph of the Sun's relative spectral flux density will suffice.
Total solar irradiance (TSI) [22] changes slowly on decadal and longer timescales. The variation during solar cycle 21 was about 0.1% (peak-to-peak). [23] In contrast to older reconstructions, [24] most recent TSI reconstructions point to an increase of only about 0.05% to 0.1% between the 17th century Maunder Minimum and the present.
Radiant flux emitted, reflected, transmitted or received, per unit solid angle. This is a directional quantity. Spectral intensity: I e,Ω,ν [nb 3] watt per steradian per hertz W⋅sr −1 ⋅Hz −1: M⋅L 2 ⋅T −2: Radiant intensity per unit frequency or wavelength. The latter is commonly measured in W⋅sr −1 ⋅nm −1. This is a ...
Flux, founded in East Greenwich in 2020 by CEO Ben Sorkin, is trying to do for outboard motor boats what Tesla is trying to do for cars Up to $1.9 million in tax credits approved for electric boat ...
Radio-frequency interference from a GSM telephone transmitting 0.5 W at 1.8 GHz at a distance of 1 km (RSSI of −70 dBm) [9] 20 000 000: Disturbed Sun at 20 MHz (Karl Guthe Jansky's initial discovery, published in 1933) 4 000 000: Sun at 10 GHz 1 600 000: Sun at 1.4 GHz: 1 000 000: Milky Way at 20 MHz 10 000: 1 solar flux unit: 2 000: Milky ...