Earth's Energy Output Compared to the Sun | Ast HW Help

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The discussion revolves around calculating Earth's energy output if it produced energy at the same rate per kilogram as the Sun. Participants clarify how absolute magnitude relates to total energy output, emphasizing that absolute magnitude is logarithmic. The user calculates the luminosity of Earth based on its mass compared to the Sun's luminosity, arriving at a value of 1.42E21 W. Further calculations lead to determining the absolute magnitude of Earth, resulting in M1=18.6. The conversation highlights the importance of understanding luminosity and absolute magnitude in astrophysics.
Kiwithepike
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Hey guys, I am new here so i hope this is in the right place. I just need help with a problem.

Suppose the Earth produced as much energy per kilogram each second as the sun does. what would be the total energy output of Earth be? how would the absolute magnitudes compare between the sun and earth
 
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Welcome to PF!

Hi Kiwithepike ! Welcome to PF! :wink:

Tell us what you think, and we'll comment.

How does absolute magnitude depend on total energy? :smile:
 
Its the measure of the absolute magnitude of luminosity at 10pc.
 
ok, and how does that depend on total energy?

eg, if you double the energy, what does that do to the absolute magnitude? :smile:
 
ok think I got it, so if mass(s)= 2.0E30kg L(s)= 3.8E26W, and Mass(E)= 6.0E24kg
then, L(s)/(s)= x/m(e) yields
1.42E21 W?
 
it doubles as well
 
Kiwithepike said:
it doubles as well

No, absolute magnitude is logarithmic … see http://en.wikipedia.org/wiki/Luminosity" for details. :wink:
 
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so i think i finally got it after some much needed rest,
is this correct. M1-M2=2.5log(L1/L2) =>
4.8-M1=2.5log(3E-6) =>
4.8-M1=-13.8 =>
M1=18.6?

And thank you so much for the help and patience with me!
 

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