Could You See a House on the Moon from Earth?

[NickJohnson22]

Hi guys! My team and I did some research into what it would take to build a house on the moon and someone wondered how big the house would have to be to see it from the earth. So we got out our calculators and Googled around and came up with a fascinating answer: http://www.movoto.com/blog/novelty-real-estate/house-on-moon/

What do you guys think. Is our math okay? Any other input?

Thanks in advance!

Nick

 

[Urwumpe]

Well, Hubble could detect a 85 meter object on the moon... you would still need a big house...

But using the accuracy of the human eye as reference, I would say you are almost right. It should of course also be of enough contrast to the lunar soil to be noticed.

 

[statickid]

if it had windows or other shiny bits it could probably be relatively small (relatively to your current numbers) and reflect flashes of sunlight making it visible to the naked eye.

on a side note it looks like a scalene triangle in the diagram. Not to be overly picky, but it could be misleading to audience.

This question can be answered by inspecting the opposite situation, couldn't it? For example, can an astronaut on the moon see the Hawaiian Islands?

 

[BruceJohnJennerLawso]

if it had windows or other shiny bits it could probably be relatively small (relatively to your current numbers) and reflect flashes of sunlight making it visible to the naked eye.

on a side note it looks like a scalene triangle in the diagram. Not to be overly picky, but it could be misleading to audience.

This question can be answered by inspecting the opposite situation, couldn't it? For example, can an astronaut on the moon see the Hawaiian Islands?

Well that doesnt take into account atmospheric haze, weather, or how well the colours contrast. I would think he could though, assuming he (or she) has reasonably good eyesight & some patience. I think one of the most amazing things to do in life would be to sit on the moon and watch a full earth rotation.

 

[statickid]

maybe as a proof of applied concept, you could get someone with excellent vision to identify a distinct feature on the moon. then just identify the feature and see how big it is. the outcome would no doubt reflect the lower limit of house size visible on the moon

---------- Post added at 07:23 PM ---------- Previous post was at 07:16 PM ----------

http://www.radford.edu/brockway/lab_angular-resolution.pdf

a similar experiment to yours

 

[RisingFury]

if it had windows or other shiny bits it could probably be relatively small (relatively to your current numbers) and reflect flashes of sunlight making it visible to the naked eye.

There are already mirrors on the Moon placed there by one of the Apollo missions. They're used to measure the distance to the Moon by shooting a laser at it and watching for the reflection. They shoot a very powerful laser at it and only get some 10 - 100 photons back, so don't count on any flashes from windows...

 

[Artlav]

How about a mirror?
Not the tiny Apollo retroreflectors, but a nice, big, polished mirror to reflect the sun back at Earth.
How big should it be for the flashes to be visible on the ground, on the background of the full moon?

 

[statickid]

There are already mirrors on the Moon placed there by one of the Apollo missions. They're used to measure the distance to the Moon by shooting a laser at it and watching for the reflection. They shoot a very powerful laser at it and only get some 10 - 100 photons back, so don't count on any flashes from windows...

I meant smaller than two New York cities. Also, I don't feel the Apollo reflectors give a very good comparison because they are very specifically designed to reflect our own light back at us, not sunlight from a different angle.

I was thinking they said you would need a house over a mile wide to see it in the ISS orbit, but when the ISS is passing in a certain way, it's the brightest thing in the sky and it's not a mile wide. I once saw the ISS go by followed by the shuttle, and actually, the shuttle was REALLY bright too, despite not being "shiny" at all. I think a big mirror would have a good chance of being seen on the moon, especially if you could control it to give the best angle

It would probably have to be bigger than anyone wants to build though... :lol:

 

[kamaz]

What do you guys think. Is our math okay? Any other input?

You're assuming that the house must be larger than the resolution limit of the eye to be noticeable.

This is not necessarily the case. For example, stars are smaller than the resolution limit of the eye, yet they are visible, because they are sources of light against a black background.

Likewise, your orange house may be visible against white lunar terrain, even if it's below the resolution limit -- it just has to emit/reflect enough light to become noticeable. It's more about the number of photons and contrast, than size.

 

[Cairan]

Indeed, Iridium flashes come from antenna panels on the satellites which are way smaller than the resolution limit ...

 

[FADEC]

Well, Hubble could detect a 85 meter object on the moon... you would still need a big house...

But is it possible to point Hubble to the Moon at all without damaging the instruments? I mean, hasn't the pointing software certain safeguards to prevent pointing Hubble to the moon (and especially the sun)?

---------- Post added at 01:05 AM ---------- Previous post was at 12:52 AM ----------

Hi guys! My team and I did some research into what it would take to build a house on the moon and someone wondered how big the house would have to be to see it from the earth. So we got out our calculators and Googled around and came up with a fascinating answer: http://www.movoto.com/blog/novelty-real-estate/house-on-moon/

What do you guys think. Is our math okay? Any other input?

Thanks in advance!

Nick

Well, I'm a terrible mathematician. But I can't imagine that one could see that house with the naked eye. Even if it reflects light. Because the moon is rather bright. And there are lots of other bright parts on the surface which I think will make it very hard to distinguish.

Imagine the apposite: you are standing on the surface of the moon and try to see big objects on earth. I think one could not even see big solar collector panels in a desert with the naked eye. You will possibly only be able to see bigger reflections from the oceans instead. It is often reported that one can see the Chinese wall with the naked eye from earth orbit, which already is a myth as far as I know.

I think one will still need a good telescope.

 

[Quick_Nick]

Orange soil? That's my house!

 

[FADEC]

Orange soil? That's my house!

Nope. Someone else has got that house before! :lol:



[ame="http://www.youtube.com/watch?v=kQ-7212_idA"]APOLLO 17 Orange Soil - YouTube[/ame]

 

[statickid]

You're assuming that the house must be larger than the resolution limit of the eye to be noticeable.

This is not necessarily the case. For example, stars are smaller than the resolution limit of the eye, yet they are visible, because they are sources of light against a black background.

Likewise, your orange house may be visible against white lunar terrain, even if it's below the resolution limit -- it just has to emit/reflect enough light to become noticeable. It's more about the number of photons and contrast, than size.

Yeah, how many star discs have we resolved? Two? Stars aren't even within the resolution limits of the most powerful telescopes.

If the mirror were near the terminator of the moon, it could catch sunlight without being against a bright moon surface