# Total solar luminosity **URL:** \ **Category:** Factual Questions\ **Created:** [April 18, 2014, 1:23pm UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414 "2014-04-18T13:23:39Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![mandala](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mandala/32/95_2.png) [@mandala](https://boards.straightdope.com/u/mandala)\ **Post date:** [April 18, 2014, 1:23pm UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/1 "2014-04-18T13:23:39Z")
If I could see the entire electromagnetic spectrum - from radio to gamma radiation - how much brighter would the Sun appear to me? And what if I could ‘see’ the solar neutrino emission as well? Conversely, if I could see only the “invisible” portion of the EM spectrum, would the Sun be visible? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 18, 2014, 3:02pm UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/2 "2014-04-18T15:02:46Z")
> [@](#): > > Conversely, if I could see only the “invisible” portion of the EM spectrum, would the Sun be visible? Absolutely. [Here are some pictures](http://cumbriansky.files.wordpress.com/2010/08/sdo-all-pix.jpg). In almost every wavelength we’ve ever observed in, the Sun is still the brightest object in the sky (in radio, the center of our Galaxy is brighter, but the Sun is still second-brightest). ---
**Author:** ![mandala](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mandala/32/95_2.png) [@mandala](https://boards.straightdope.com/u/mandala)\ **Post date:** [April 19, 2014, 6:02am UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/3 "2014-04-19T06:02:47Z")
> [@Chronos](#): > > Absolutely. [Here are some pictures](http://cumbriansky.files.wordpress.com/2010/08/sdo-all-pix.jpg). In almost every wavelength we’ve ever observed in, the Sun is still the brightest object in the sky (in radio, the center of our Galaxy is brighter, but the Sun is still second-brightest). I find it difficult to believe that an object 27,000 lightyears away can outshine the Sun in _any_ wavelength. :eek: ---
**Author:** ![Carl\_Pham](https://avatars.discourse-cdn.com/v4/letter/c/e9a140/32.png) [@Carl\_Pham](https://boards.straightdope.com/u/Carl_Pham)\ **Post date:** [April 19, 2014, 6:50am UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/4 "2014-04-19T06:50:55Z")
Here’s a handy online calculator that will integrate the black-body spectrum for you: [http://www.spectralcalc.com/blackbody\_calculator/blackbody.php](http://www.spectralcalc.com/blackbody_calculator/blackbody.php) Putting in 5800K for the black-body temperature of the Sun, and setting the integration limits to 400 and 700nm, I find that the ratio of the visible radiance to total radiance is about 0.36. That is, what you see with your eye constitutes about 36% of the total energy radiated by the Sun. So if you could see all wavelengths I suppose it would look in some sense about 2.7 times brighter. ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [April 19, 2014, 3:52pm UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/5 "2014-04-19T15:52:49Z")
> [@mandala](#): > > And what if I could ‘see’ the solar neutrino emission as well? This is 3% of the energy output of the sun. ---
**Author:** ![drewtwo99](https://avatars.discourse-cdn.com/v4/letter/d/d07c76/32.png) [@drewtwo99](https://boards.straightdope.com/u/drewtwo99)\ **Post date:** [April 19, 2014, 4:02pm UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/6 "2014-04-19T16:02:46Z")
It would depend of course on how the receptors in your eyes worked, how sensitive they were to each wavelength, and that sort of thing. The intensity/brightness of radiation really depends as much on the biology of the eye as it does on the physics of the radiation. For example, the human eye can see very low intensities of certain wavelengths of light, but cannot see other wavelengths within the visible spectrum at the same intensities. So let’s say your eye could see radio and microwave and ultra violet and x ray and gamma ray radiation. But maybe you can only perceive the radio and microwave radiation at relatively high intensities, and anything below that looks invisible to you. If that were the case, that radiation might not make the sun look any brighter to you. Eyes are amazing, and weird things. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 19, 2014, 4:27pm UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/7 "2014-04-19T16:27:41Z")
> [@](#): > > Quoth **mandala** : > > I find it difficult to believe that an object 27,000 lightyears away can outshine the Sun in any wavelength. Funny story about that: The world’s first radio astronomer built a big antenna in his backyard, and discovered that he was getting radio waves from somewhere in the sky. It rose and set every day, and so he naturally assumed that the source was the Sun. But it just so happened that he was making his first observations in early December, and as the months passed, he realized that it was rising and setting every _sidereal_ day, not every solar day: In other words, the source was among the stars, not the Sun. Early December just happens to be the time of year when the Sun is in the same area of the sky as the galactic core. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [April 20, 2014, 6:50pm UTC](https://boards.straightdope.com/t/total-solar-luminosity/686414/8 "2014-04-20T18:50:15Z")
> [@Chronos](#): > > Funny story about that … Cool, thanks for sharing!