The lighter side of real estate

Size Does Matter: How Big Would a Moon House Need to Be to See it from Earth?

The Movoto team often thinks about moon life and calling the planet home. Soon we were asking: How big would a moon house need to be to be seen from Earth?

Kristin Crosier


44 articles, 3 comments


Ever since Neil Armstrong first set foot on the Moon, Americans everywhere have often found themselves pondering the bright orb that is Earth’s natural satellite.

Children and adults alike dream of becoming astronauts and joining the list of those such as the Apollo 11 astronauts who have traveled to the Moon. At Movoto Real Estate, we practice moonwalking in our free time and find ourselves buying space food off the Internet just to see how it tastes.

With all of our daydreams about visiting the Moon, we couldn’t help but imagine what it would be like to become the actual man in the Moon. This brought us to thoughts of building a home on the lunar sphere and whether you could see it from Earth.

Then came the million-dollar question: How big would our Moon home need to be for someone standing on Earth to see it with the naked eye?

Our house would need to be approximately 24.56 miles wide, or the length of 437 football fields. Read on to find out how we came to that conclusion.

Word of warning: This article is somewhat more math heavy than usual, so you may want to skip the next part if large numbers tend to make you flustered.

The Math Behind the Mansion

How did we come up with this crazy number? First, we scoured the Internet for applicable mathematical equations, but were unsuccessful in our quest to answer the question.

We then called in reinforcements–our resident science whiz, to be exact. He turned us onto the Rayleigh criterion, which allowed us to create an imaginary triangle between someone on Earth and the edges of our Moon house.

The formula we used looks like this, where:

  • θ is the angular resolution, or the pupil’s angle of visibility
  • λ is the wavelength of light
  • D is the diameter of the aperture lens (in this case the diameter of the eye’s pupil)

We chose orange as our color of light–we needed a specific color to calculate wavelength–and used a pupil diameter of 7 millimeters (the average size for a dark-adjusted eye).

This led us to our missing angle size, which we then used in an equation for tangent to calculate the necessary width of our house. It turns out our house needs to be at least 24.56 miles wide to be seen with the human eye.

By the way, our calculations merely make the house large enough to be visible from Earth–the home would need to be even larger if you wanted see more detail, say to locate the windows and front door.

To keep things simple, we went with a square house, which means that our house would be approximately 603 square miles, or about 16,817,741,883 square feet.

That makes our house slightly larger than the city of Houston. Or, for those of you more familiar with New York, our home is about twice the size of New York City.

Larger Than Earth’s Largest House

Not surprisingly, our massive Moon house is quite a bit larger than the largest house in the world. That title currently belongs to the residence of the richest man in India, Mukesh Ambani.

In 2010, Ambani’s current residence was completed–at 27 stories high and 400,000 square feet, the home is easily the largest on Earth.

It’s also one of the most luxurious, costing $1 billion to build and including:

  • A gym and dance studio
  • Ballroom
  • 50-seat cinema
  • 3 helicopter pads
  • Staff of 600 people

Yet Ambani’s monstrosity is no match for our Moon house, which just happens to be more than 42,000 times larger.

On a roll, we couldn’t help but calculate the size of our house in other parts of space–both of which are also larger than Ambani’s massive estate.

To Low Earth Orbit and Beyond!

We now know the size of our brightly orange–colored Moon house, but what about how its size might change in the space between the Earth and the Moon?

In Low Earth Orbit, the atmosphere that extends from Earth’s surface to an altitude of 1,200 miles, our house would only need to be about 455,260 square feet, or 42,295 square meters.

Our Low Earth Orbit home would be five times larger than the International Space Station, which is approximately 85,024 square feet. That means you could house a lot more astronauts than the five bedrooms found in the ISS.

Geostationary Orbit, which exists above Low Earth Orbit, would require the width of our house to be about 2.3 miles to be visible from our planet. This would bring the size to 145,755,177 square feet, or 13,541,099 square meters.

In other words, that’s a pretty hefty house.

How you would get your building materials (and furniture!) there is another story altogether. Good thing we already made a handy calculator for you to shoot your house into space.

We’ll leave you to it on this note: The naked eye can see as far into space as the Andromeda Galaxy–2.5 million light-years away–because it’s so bright.

So if you really want your Moon house to stand out, cover it in outdoor lights. And yes, we are talking about more than even your extreme holiday lights display.

Editor’s Note: The Movoto blog team would like to extend a special thank you to fellow Movoto employee Kevin Prasad for coming up with the awesome idea behind this article.

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posted on: January 9, 2013
584 views, 3 comments


  1. David

    I live in San Fran, everything is bigger than mine… ;(

  2. Adam

    This isn’t right. The Rayleigh criterion assumes diffraction-limited optics. The human eyeball isn’t that good. Angular resolution for our eyes is a few arcminutes (give or take, depending on an individual’s eyesight), or about ten times worse than what you calculated. The angle is more like 0.05 degrees instead of the 0.00589 degrees that you used. The Moon-house would need to be about ten times larger to be visible with the naked eye from Earth.

    • Megan in response to Adam

      Does the shape of the eyeball play a factor in the angular resolution? For instance, I have “egg-shaped” eyeballs – would that change the number drastically?


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