Jump to content


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Underground Observatory

  • Please log in to reply
47 replies to this topic

#26 quantumac


    Viking 1

  • -----
  • Posts: 894
  • Joined: 17 Dec 2007

Posted 20 September 2009 - 09:16 PM

Many of the well-off observatory owners will actually build their facilities highly elevated, in order to get away from ground effects and humidity.

Alas, I'm not one of them. My observatory is elevated about three feet, but it's also located in a shallow valley. My seeing isn't the greatest in the world. But hey, I actually HAVE an observatory, which is way better than not.

#27 blueman


    Photon Catcher

  • *****
  • Posts: 6322
  • Joined: 20 Jul 2007
  • Loc: California

Posted 26 September 2009 - 11:29 PM

We at the LAAS site have a half underground observatory. We get snow and rain, but no real problems with moisture and we have a permanently mounted 16" in it.
There is a picture on this link.

#28 Rick Woods

Rick Woods


  • *****
  • Posts: 19121
  • Joined: 27 Jan 2005
  • Loc: Inner Solar System

Posted 28 September 2009 - 07:48 AM

Percival Lowell built an observatory recessed into the ground for his 42" Clark reflector. The results were terrible, and he never got any sort of decent seeing out of the telescope. The rusting hulk of the OTA now sits outside along a walkway at Lowell Observatory as a garden ornament.

I suspect that if you build underground, you'll regret it for a long time to come. Sorry to be a downer.

#29 Bowmoreman


    Clear enough skies

  • *****
  • Posts: 9385
  • Joined: 11 Sep 2006
  • Loc: Bolton, MA

Posted 29 September 2009 - 12:02 PM

Unless you have it in a really arid climate, you are going to have huge issues with humidity... There is no way to really avoid this.

the deeper your hole/walls, the colder it will naturally be (unless you simultaneously heat it)... this causes relative humidity to skyrocket. If you dehumidify, that heats it in the process...

Depending on how rapidly the air in the underground space is (or can be) exposed to outside airflows will determine if you will get so humid as to actually reach saturation and the resultant condensation - on every surface...

Even Super Insulating is not going to help you, because, unless you can super insulate AND also make it 100% airtight (versus outside air) - the outside air (warmer and therefore carrying higher moisture content) will get in and be exposed to the colder area below ground... and raise RH and/or condense...

And, you don't want to have a 100% airtight observatory anyways - defeats one of the main points - instant acclimation to ambient temp... You've got two conflicting requirements with such a design.

Here's a real world datapoint: I built a super insulated wine cellar in my 8' deep basement. It has R90+ insulation in the ceiling, and R68+ in the walls. Full vapor barrier. Exposed concrete floor inside (so has a heat "sink" at deep earth ambient temperature, which here in MA is around 55F).

In Winter, the air temperature stabilizes at a low of 57F, in Summer, it gradually peaks at a high of 63F; with gentle swings in fall and spring to/from those values...

The humidity varies from 80% in summer, to around 55% in winter. This is totally passive, and with COMPLETE vapor barrier (and double doors as well!).

Not a telescope friendly climate:

Too humid and NEVER at ambient to outside...

Sorry, I just don't think having the actual observatory be undergound makes any kind of sense...

It would only work if you had very highly regulated HVAC control of temperature and humidity, AND also had massive insulation...

Why bother??? Uber-expensive, fiddly, etc...

Sorry to "rain" on the idea parade...

Again, this only applies to areas that HAVE humidity and temperature swings... it might work out ok in Arizona, New Mexico, Nevada, Utah and other places similar...

clear enough skies

How do you handle the humidity in your cellar?

Humidity in a Wine cellar is a GOOD thing; the higher the better... what you do NOT want is condensation...

Pretty much the once a day ingress/egress to snag a bottle probably mixes enough air (even with dual air-locked doors 36" apart) to ensure that it would never get out of control.

In the main part of my basement, however, I run de-humidifiers from about March through October... else IT gets too humid, and there's lots of stuff down there that does NOT like high humidity!

clear enough skies

#30 starquake


    Viking 1

  • -----
  • Posts: 586
  • Joined: 02 Feb 2008
  • Loc: 47.114740, 18.241846

Posted 17 November 2011 - 01:05 AM

Just a little update on my slow-going underground observatory project. Meanwhile I've decided to build a little room next to the dome for a computer and some stuff to keep me warm. I've just finished with the concrete walls, and made a little video in timelapse style using hundred something pictures to celebrate this. Have a look, if you have some time:


Now all I have to do is to make the roof for the warm room and the dome for the observatory. That's the project for the winter.

About the condensation on the walls: I've added some large-diameter pipes with automated venting units to wipe humid air out of the room, and some other tricks to prevent humidity.

I don't have a pier, because I will use my custom horseshoe mount in the dome, so no need for a pier.

#31 seryddwr


    Innocent Bystander

  • *****
  • Posts: 3443
  • Joined: 19 Feb 2010
  • Loc: La-la land.

Posted 17 November 2011 - 03:41 AM

I can see why it's taking a while!

#32 Starhawk


    Space Ranger

  • *****
  • Posts: 6189
  • Joined: 16 Sep 2008
  • Loc: Tucson, Arizona

Posted 17 November 2011 - 09:37 AM

What you're talking about us called a Kiva in the southwest. Great for human comfort. It would be better as a basement under an observatory, though. But if it is here in AZ, it could solve a lot of problems. The rim needs to be above ground level to keep rainwater out. The roll off roof presents a thorny problem, with a permanent patch on the ground occupied with the roof roll space.

Very often the air responsible for bad seeing is close to the ground, so this would make that worse. Look up the Stellar Cellar- built because of an unreasonable HOA.


#33 csa/montana


    Den Mama

  • *****
  • Posts: 88459
  • Joined: 14 May 2005
  • Loc: montana

Posted 17 November 2011 - 10:59 AM

Wow! That's a lot of concrete! You are certainly making a sturdy, beautiful observatory!

Heck, you even wore your yellow lab out! :lol:

Thanks for the great update, we are anxious to keep following your progress! :)

#34 StarWrangler


    Viking 1

  • -----
  • Posts: 978
  • Joined: 03 Sep 2004
  • Loc: Three Rivers, MI U.S.A>

Posted 17 November 2011 - 12:14 PM

In a old ATM book showed a English yoke mount that was in a trench,


#35 starquake


    Viking 1

  • -----
  • Posts: 586
  • Joined: 02 Feb 2008
  • Loc: 47.114740, 18.241846

Posted 17 November 2011 - 03:18 PM

Thanks for the kind comments. :)

About the amount of concrete: I carried up the hill about 6.5 tons of concrete sofar, climbing about 20000 steps (and another 20000 on the way back), walked about 40 kilometers, and climbed a mountain about 5000m high (and back down).

The stats are also valid for my dog, because he was my only workmate (well okay, he carried no concrete at all), following me with every turn.

I'll start creating my pipe-bending machine next week, as I plan to have an all metal 4 meter dome.

Btw, the name of the observatory is Talpa Minor, because it sounds constellationish, but in latin it means "Little Mole", and comes from a Czech cartoon: http://en.wikipedia....iler_character)

#36 wormstar



  • *****
  • Posts: 1160
  • Joined: 23 Nov 2009
  • Loc: Usually Earth

Posted 18 November 2011 - 11:54 AM

Mr Starquake- you are one VERY determined individiual!!!
I consider myself to be ambitious, but your effort makes me feel lazy!!! You carried 6.5 tons of mix up a hill in a bucket??!!!
I really hope the end result is good for you.

#37 J_D_Metzger


    Surveyor 1

  • *****
  • Posts: 1859
  • Joined: 13 May 2004
  • Loc: Tucson, AZ

Posted 20 November 2011 - 12:20 PM

I built a sunken observatory last year:

The Stellar Cellar

To borrow a phrase from the real estate business, whether it will work depends entirely on three things: location, location, location.

I live in the desert southwest. I didn't have to worry about ground water or humidity. I did have to make sure there was adequate drainage (we can get heavy rains in our monsoon season), but that was really the only major consideration. BTW, the Stellar Cellar made it through the monsoon this summer completely dry.

#38 Project Galileo

Project Galileo

    Viking 1

  • *****
  • Posts: 843
  • Joined: 14 Nov 2007
  • Loc: Jefferson County, Colorado

Posted 24 November 2011 - 09:43 AM

Interesting thread. Good luck!

#39 starquake


    Viking 1

  • -----
  • Posts: 586
  • Joined: 02 Feb 2008
  • Loc: 47.114740, 18.241846

Posted 22 May 2012 - 11:49 AM

Hi again, I hope you don't mind another little update on my underground project, as finally I've started to work on the dome. On the bottom of the image you may notice how deep underground the main dome part is. One level of concrete bricks is about 10" high. Next to the dome you can find my even-deeper-underground shelter room still without a roof and door that will be heated and equipped with an automated air-ventilation unit to fight moisture and bad air. The room will also contain a small desk, chair, computer, maps, etc.

The dome structure (cca. 12.5 feet in diameter) is now about 2/3 part ready, but I had to stop welding because of heavy rains this week. The rusty bit of metal is only temporarily welded to the dome slit to maintain position until the structure is ready.

I've already had a rotating mechanism, but it is now removed as I plan to change it to a more sturdy one and waiting for parts to come in. The structure will be covered with 1.5mm thick metal sheets, and I still hesitate about the opening style of the dome slit.

So, this is my keyhole to the universe:

Posted Image

If I should post elsewhere, pls let me know.

#40 Mary B

Mary B

    Vendor - Echo Astronomy and Electronics

  • *****
  • Vendors
  • Posts: 3168
  • Joined: 21 May 2010
  • Loc: Minnesota

Posted 22 May 2012 - 07:28 PM


#41 StarmanDan



  • *****
  • Posts: 3839
  • Joined: 27 Aug 2007
  • Loc: Deep in the heart of Texas

Posted 23 May 2012 - 11:42 AM

Might take a look at this thread:


#42 TheThingy


    Lift Off

  • -----
  • Posts: 11
  • Joined: 11 Apr 2012
  • Loc: Ireland

Posted 23 May 2012 - 01:08 PM

That looks like the bees knees, look forward to seeing the finished article

#43 seeindoubles


    Vostok 1

  • -----
  • Posts: 111
  • Joined: 15 Jan 2012
  • Loc: Pacific Northwest-Oregon

Posted 24 May 2012 - 09:18 PM

As long as you have a method of ingress and egress and good drainage why not? Didn't the Mayan's do something similar?

#44 Starhawk


    Space Ranger

  • *****
  • Posts: 6189
  • Joined: 16 Sep 2008
  • Loc: Tucson, Arizona

Posted 25 May 2012 - 09:21 AM

No, the Mayans went UP. They built pyramids to raise their observatories.

I'm still not sure why there is the urge to go underground for observatories. I typically look for reasons difficult solutions are necessary.

Have a plan in your back pocket to make it into a basement.


#45 starquake


    Viking 1

  • -----
  • Posts: 586
  • Joined: 02 Feb 2008
  • Loc: 47.114740, 18.241846

Posted 21 June 2013 - 12:40 PM

Some more update on my never-ending progress with my underground observatory. Now the dome rolls and as it was like this for the whole winter (and winter just ended here in april), it now has a nice layer of rust. Actually I like this colour, so I was seriously thinking to paint it to something similar, instead of white. Anyhow, all left is making the openings two piece door, and the roof for the computer room. It should be finished now within a month including painting.

I was worried that the large metal will scoop heat from the Sun (and it really does), but it seems that the ground in fact does its job, and keeps the dome pretty cool.

Posted Image

Posted Image

#46 nicklane1


    Mariner 2

  • *****
  • Posts: 279
  • Joined: 04 Mar 2008

Posted 21 June 2013 - 03:53 PM


Impressive. Love the views too.

#47 csa/montana


    Den Mama

  • *****
  • Posts: 88459
  • Joined: 14 May 2005
  • Loc: montana

Posted 21 June 2013 - 04:56 PM

Very nice! :bow:

We'd love to see some pictures of the interior!

#48 rlandsboro


    Vostok 1

  • -----
  • Posts: 154
  • Joined: 23 Feb 2012
  • Loc: Scottsdale, AZ. USA

Posted 21 June 2013 - 06:01 PM

If you like the color you might just clear coat the rusted exterior. Around here we call that "rustic" :) and it is popular.

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics