Solar Luminosity

[xmo1]

Are there momentary fluctuations in solar luminosity that would cause the sky to brighten or dim during the day or night? Why does the luminosity of the Moon seem to vary during full moon phases? Sometimes it is very bright, and sometimes it is not. URLs if you please. <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>

 

[doubletruncation]

In a sense, aurorae are brightenings in the sky caused by a fluctuation in the solar luminosity. But I presume that what you're asking is if the average surface brightness of the sky changes as a result of solar variability. The sun does actually vary at about a 1% level due to the presence of sunspots (this was measured by the solar maximum mission back in the 80s - see for example: http://solarscience.msfc.nasa.gov/SMM.shtm ). It is actually brightest when there are more spots, and most of the fluctuation in brightness comes in the UV/X-rays. In the optical the variability is much lower (much less than 0.1% IIRC - see for example: http://aanda.u-strasbg.fr:2002/articles/aa/full/2004/38/aa0028-04/aa0028-04.html ). 1% variations are too small to really detect by eye (the best visual variable star observers can detect variations on the order of a few percent, 1% is really too low), the actual variations that you would even be able to see in the optical are much smaller than that still.<br /><br />Re. the full moon brightness changes. There are a number of different factors contributing, solar variability is not one of them. See for example:<br />http://curious.astro.cornell.edu/question.php?number=529<br /><br />I'm not really sure that the variations are that big of an effect though, I think a lot of it could be what time of night you happen to go out and look at it, it doesn't look quite as bright when it's closer to the horizon. <div class="Discussion_UserSignature"> </div>

 

[xmo1]

What I have seen occured in the day time sky where the sky got brighter for about 1/2 second, but I have seen it happen more than once. This is not caused by the Sun from what you have described. Could be a local manufacturing process, heat lightening, a physiologically related cause, or any or a range of other possibilities. <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>

 

[xmo1]

"I've never heard of a solar flare that was so bright"<br /><br />Could be a daytime aurora I guess. I noticed the effect during this solar max. I have a hunch the Sun is causing global warming, but I don't know why except that my attention has been drawn to it as a cause.<br /><br />"when the moon is really at opposition"<br /><br />Thanks. That explains my observations. I'd bet Stonehedge was an academic center for the study of Astronomy. I seem to get more out of a weeks worth of outside observation than two months in the classroom. <div class="Discussion_UserSignature"> <p>DenniSys.com</p> </div>