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Did the apparent magnitude of the Sun change in the past 1000 years or so? If so, for what reasons?

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  • $\begingroup$ @Jan Dvorak. Absolutely correct. I assumed questioner was looking for a variation due to the sun itself. A bad assumption on my part. I will update my answer after I determine difference. $\endgroup$ – jmh Jun 19 '17 at 20:38
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No. The apparent magnitude of the sun is constant to within 0.2% How long it has been that way is only speculation since measurements aren't available. 1000 years is a very short time period in the life cycle of a star. Its safe to say yes its been constant for 1,000 years. There is a small variation based on the 11 year sun spot cycle but this variation is reported at less than 0.1%. There is also a larger variation due to the difference in Earth-to-Sun distance caused by the earths elliptical orbit. This effect is about 7%. This is no due to the sun but rather due to the eccentricity of Earths orbit. There are also minor effects with a cycle time or much greater than 1,000 years. These also due to variations in Earths orbit.

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    $\begingroup$ Don't discount the variation due to Earth's orbit eccentricity. $\endgroup$ – John Dvorak Jun 19 '17 at 20:33
  • $\begingroup$ @Jan Dvorak. Absolutely correct. I assumed questioner was looking for a variation due to the sun itself. A bad assumption on my part. I will update my answer after I determine difference. $\endgroup$ – jmh Jun 19 '17 at 20:39
  • $\begingroup$ Could you add how the brightness of the Sun 1000 years ago is known? $\endgroup$ – Rob Jeffries Jun 20 '17 at 6:39
  • $\begingroup$ I stated it was only speculation really. $\endgroup$ – jmh Jun 20 '17 at 11:09

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