Let’s Replicate the Sun… With Light Bulbs!

An image from the 2017 Great American Eclipse.

Well, the Great American Eclipse came and went. It was astonishing, amazing; everything I had ever hoped and dreamed it would be. I watched in awe as the sun was swallowed bite by bite by the encroaching black Moon, slowly devouring it until all that remained of the sun was a golden sliver. And then, it occurred.

I viewed the eclipse from south-eastern Nebraska. Here, totality lasted 2 minutes and 38 seconds. Take that time and multiply it by a million. This is how much time I spent hearing about ‘not looking at the sun with your naked eye’ in the time before the eclipse...

Yes, the sun is bright. So bright, in fact, that even at 739 million Trump towers away, it shines bright enough to burn the retinas of an unsuspecting sun gazer severely enough to cause permanent blindness.

The Sun, which is actually quite bright.

We need the sun to live. It provides warmth for our planet to maintain liquid water, light for resident life forms to perform their daily routines, and a deadly shower of ultraviolet radiation and charged particles that often afflict us with cancer. But we usually forgive the sun for that last one due to the vital importance of the first two things.

But could you duplicate the blinding luminescence of the sun… with light bulbs?

Your average, incandescent light bulb.

Okay, there are a lot of things that need to be addressed before we just start throwing numbers around. First of all, for the purpose of this article, we are only talking about reproducing the blinding light of the sun, not it’s heat nor it’s deadly array of charged particles and radiation (these delicacies would require numerous ‘space camp fires’ and several Large Hadron Colliders).

Secondly, we need to define what kind of light bulbs we are using. When dealing with light bulbs, you basically have 3 options; incandescent bulbs, those weird swirly ones, and LEDs. LEDs are the most efficient in terms of converting energy into light, with a conversion coefficient of around 80%. Plus they are largely unidirectional, which means they emit most of their light in one direction, in this case, the Earth. So, if you wanted to replicate the daunting power of the sun, you should probably use these.

An LED light bulb from Philips. (Disclaimer: I am not affiliated with Philips in any way.)

Finally, we need to define how we are configuring the lights. This basically entails deciding what shape to put these light bulbs in order to use the smallest number of them to duplicate the sun. Putting them in a sphere sounds like it would be the most volume efficient, and you’d be right. However, this would cause the inner light bulb’s light emissions to never actually reach the surface, and instead be converted into heat or kinetic energy by the outer layers of light bulbs. Therefore, the most efficient lighting formation to avoid this phenomenon is a circle.

Now the fun part. The power output of the sun in is 3.826*10²⁶ Watts. By using standard, 22 Watt LED bulbs (100 Watt incandescent bulb equivalent), and that 80% efficiency I quoted earlier, you end up having to use 2.17*10²⁵ (~22 septillion) bulbs. That’s a lot of light bulbs. This number is equivalent to a modest estimate of how many stars there are in the observable universe. If wishes were horses… If stars were light bulbs…

Some packing examples to show how to arrange circular objects.

So now, let’s arrange our light bulbs into a circle to see how big this thing really is! A standard, A-series light bulb is 60 mm in diameter. If we pack them with the best 2-D packing efficiency (hexagonal), each bulb takes up a surface area of 2700 mm², or 0.0027 m². Multiply that by our number of bulbs, and you get 5.87*10²² m². Form that area into a circle, and you end up with an abomination of light bulbs that is 2.73*10¹¹ meters in diameter. This size is ironically 83% larger than the distance from the Earth to the sun itself.

This structure would be enormous. At the same distance as the sun, this array of light bulbs would appear 45,000 times larger than the sun in area, taking up a swath of sky 85 degrees across. It’s so big, that daytime would actually last 47% longer due to the high angle of incidence of the very edges of the array, lengthening average daylight time by more than 5 hours.

Side view drawing showing the daylight elongation. *Not to scale.

The light from our structure wouldn’t be as intense as the sun, however. In fact, you could probably stare directly at it with little consequence to your frail retinas. But the truth is, this structure wouldn’t last long. The average light bulb weighs somewhere in the ballpark of 40 grams. This would award our full LED bulb array with a mass of 8.68*10²³ kg. This mass is a sizable fraction of the mass of the Earth itself (15%), and is in fact larger than the mass of the planet Mars. A structure this massive comprised of LED light bulbs would surely collapse under its own weight due to gravitational stresses.

Mars, less than 11% the mass of Earth

But that’s okay, because it probably could never be constructed in the first place. There isn’t enough silicon in the solid bodies of the solar system to manufacture enough glass to build the actual bulbs required for our array. Plus, most LEDs use gallium, an element that is already somewhat rare to begin with. Even if you could get past the manufacturing stage, the structure would be impossible to assemble. With modern rocket technology, it would take more than a billion-billion SLS launches just to get all of the light bulbs into space, and at the rate NASA launches, that could be upwards of a billion-billion years.

The point of this is that the sun is bright; brighter than we could ever hope to replicate with the power of modern day technology. Overall, I think the sun does a pretty good job doing what it does. It keeps us warm in the summertime, it turns off at night when we sleep, and it knows when it will be cloudy so it doesn’t have to come out. So, the next time someone tells you not to look directly at the sun for any reason, you can assure them that you would never stare into the fiery inferno of 22 septillion LED light bulbs.

This looks dangerous. Would not advise.