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Re: Is the Sun losing mass?

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Simon Roberts wrote:

> 'what me worry?'

Are you talking to yourself?
 
> (version 2)
> 
> givens.

Your English is bad, too.
 
> the mass of the Sun as approximately m_sun = 2E+10^30 kg.

The correct value is M☉ ≈ 1.988435 × 10³⁰ kg.  You must be more careful with 
your numbers: A difference of 0.02 × 10³⁰ = 2 × 10²⁸ already equals 20 
octillion kilograms here (short scale).

If you do not know the correct value, you can calculate it approximately by 
plugging the data of Terra’s (approximately circular) orbit into

   a_r = g

  v²∕r = G M☉∕r²,

where v is Terra’s average orbital speed (you get that from the average 
orbital radius r and the period).
 
> the power of sunlight near Earth as 13677 watts/m^2. <- [oops sloppy typo]

Power is measured in W, not W∕m².

The value is irrelevant unless you use it properly.
 
> [should be '1367' not '13677' the typo does not affect the result].

Yes, your result is *still* wrong.
 
> the radius of orbit as approximately 150E+10^9 m.

The radius of Terra’s orbit only matters if you actually use it.  So far 
there is no indication that you do.  Your calculation lacks all marks of
the required scientific rigor.  GIGO.

AISB, it is easier and better to use Sol’s luminosity (as *measured* by
e.g. NASA and subsequently *defined* as a unit [L☉] by the IAU).
 
> the equation E = mc^2 (different 'E').
> 
> W == watt == (kg)m^2 / sec^3 = (joules / sec).
> 
> result.

*After* I told you already.
 
> neglecting all else the Sun is losing approximately

Which is another reason why this is all wrong.
 
> 1 part in 15E+10^12 PER YEAR of its mass, m_sun.

Wrong, it is approximately 6.795 × 10⁻¹⁴ M☉/a due to stellar nuclear fusion.

<http://www.wolframalpha.com/input/?i=3.848%C3%9710%5E26+J%2Fc%5E2+*+86400+*+365.25%2F(mass+of+Sol)>
 
But note that this is an *approximation*: As Sol loses mass, she does not 
require as much radiation pressure to sustain herself against her self-
gravity, so the energy output decreases as well.

> 1  : 15, 000, 000, 000, 000 [in 365 days].
> 
> 1 : 15E+12 translated to
> 
> a change of ( - 130 E+15 kg / year ) approximately but close in magnitude.
> 
> not to shabby.

The correct value is 1.351 × 10¹⁷ kg/a.  You are off by ca. 5 quadrillion 
kg/a (short scale; ca. 3.7 %).
 
<http://www.wolframalpha.com/input/?i=3.848%C3%9710%5E26+J%2Fc%5E2+*+86400+*+365.25>

(In scientific notation, the base is always less than 10.)


PointedEars
-- 
A neutron walks into a bar and inquires how much a drink costs.
The bartender replies, "For you? No charge."

(from: WolframAlpha)

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Thread

Is the Sun losing mass? Simon Roberts <retenshun@gmail.com> - 2018-03-14 00:21 -0700
  Re: Is the Sun losing mass? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-03-14 21:47 +0100
    Re: Is the Sun losing mass? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-03-14 23:50 +0100
  Re: Is the Sun losing mass? Simon Roberts <retenshun@gmail.com> - 2018-03-14 15:51 -0700
    Re: Is the Sun losing mass? Simon Roberts <retenshun@gmail.com> - 2018-03-14 17:15 -0700
      Re: Is the Sun losing mass? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-03-19 03:34 +0100
        Re: Is the Sun losing mass? Volney <volney@volney.invalid> - 2018-03-19 00:04 -0400

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