Make a Wall Mirror Observatory for Backyard Astronomy




You're an erstwhile astronomer, but the most advanced equipment you have is a pair of binoculars?  Tired of craning your neck to make observations?  Well, worry no longer! Here's a nifty trick that is also a fun and easy way to show people the stars and planets.  In this Instructable, I will show you a simple way to make observing the skies easier.

Items you will need:
-a large flat mirror, at least 1 ft square. A couple feet on a side would be perfect.
-binoculars or spyglass
-some kind of support. A 2x4 works great.
-some clean dry rags (optional, but recommended)
-an outdoor table, but a level patch of ground should work too

Step 1: Take Your Mirror Off the Wall, and Put It Outside.

This step is pretty self-explanatory.  Put the mirror on a large stable table or on the ground.  Make sure the shiny side of the mirror faces up!  Clean any dust or gunk off, and remove any condensation that may form.

Step 2: You Don't Need a Tripod.

If you're a frequent visitor to this site, I'm going to go ahead and assume that you either have some scrap lumber around or have it readily available. You'll want a 2x4 about 5 feet in length, or a similar board.  

To make your observations and keep them fairly steady, prop the board against the table.  Use one of your feet like a chock on the bottom of the board and you till be able to lean against the board and the table, provided you have a sturdy enough table.  

Place your binoculars (or whatever) on the top of the board. You will find that the flat edge of the board allows a good contact area to hold your optics still, but allows you to pivot easily to sweep across the sky.

Tip: practice controlling your breathing to hold still while trying to look at faint objects.  Exhale slowly and in a controlled manner while adjusting your focus for best results.  If you have done any low light photography w/o flash using point-and-shoot cameras, you are probably already familiar with this idea.

Step 3: Observe

As Yogi Berra said "You can observe a lot just by watching"

So, get out your star chart, gather round your mirror table and see the sights!  When the mirror starts to get condensation on it, buff it off well with your soft cloth. Depending on your climate, this may be frequent.

I took the below picture of the moon with a point and shoot digital, not even using my monopod/board.  It's not great and I'm sure you'll do much better, but it's 100 times better than the result of pointing the camera up at the moon with my head tilted back.

That's it! Have fun!



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    6 Discussions


    4 years ago on Introduction

    Rear projection tvs have huge first surface mirrors and people are junking them. Help yourself!


    8 years ago on Introduction

    I like this idea. But it would take me a long time to get used to seeing the stars backwards. Good work!


    8 years ago on Introduction

    It is a nice idea and it works! I was thinking about this for some time but decided not to do it. From my personal search on this here are two suggestions:
    1. Make it smaller and portable. Check out this patent to see how US4278320
    2. If you can afford it buy a good quality mirror without a glass cover to avoid aberrations. Check Edmund company for optics (they are expensive).

    1 reply

    Thanks for comment! I thought a large mirror would be useful for allowing a group of people to gather around and look at the same objects. I think it would be great for viewing meteor showers since you can see such a large section of sky. I was trying to view the Leonid meteor shower last night, but I didn't see a single meteor, I think I missed the peak and the moon was really bright.


    8 years ago on Introduction

    Overhead projectors and old 8mm film viewers also have first surface mirrors. Surplus shed might have a nice first surface mirror for little...


    8 years ago on Introduction

    One more thing: 8x21 binoculars are useful but a pair of 10x50 will allow you to see much more (more luminous by a factor of 6.25) like the satellites of jupiter.