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.

Photo

How much open space do I need?

  • Please log in to reply
25 replies to this topic

#1 joseph.gagnon

joseph.gagnon

    Sputnik

  • -----
  • topic starter
  • Posts: 37
  • Joined: 24 Aug 2017
  • Loc: Florida, USA

Posted 18 July 2021 - 02:07 PM

I never thought I'd need to ask a question such as this, but here we are.

 

I am contemplating purchasing some property for a future home that will hopefully also be useable for astronomy purposes. The lot is fairly good sized (about 2 acres - but it's not square, about 130x550 ft), but it's completely covered in trees, mostly pine, probably about 60 feet tall. Obviously some of this will be cleared out for building, etc.

 

I'm trying to get an idea of how much sky can I see from an open area of a certain size, or looking at it in a different way, how big an open area do I need to be able to see a "reasonable" amount of sky? This is in the Florida panhandle, a little under 30 degrees north latitude.

 

Has anyone dealt with this question? Any ideas are welcome.


Edited by joseph.gagnon, 18 July 2021 - 02:13 PM.


#2 matt_astro_tx

matt_astro_tx

    Apollo

  • -----
  • Posts: 1,493
  • Joined: 19 Jan 2021
  • Loc: Dallas, Texas

Posted 18 July 2021 - 02:16 PM

I have the opposite problem.  I have 2 acres of about the same dimension, and the original owner cleared the land of ALL the trees.  We're now having to plant some to gain some semblance of privacy.

 

Interested to see what folks have to say.


  • Dobs O Fun likes this

#3 Richard O'Neill

Richard O'Neill

    Mercury-Atlas

  • *****
  • Posts: 2,670
  • Joined: 19 Aug 2014

Posted 18 July 2021 - 02:22 PM

How do you define a "reasonable" amount of sky?

 

 I prefer an open 360 but will settle for nothing higher than 15 degrees from an azimuth of 40 to 320 degrees. Even with that I want a clear wide view to the south of at least a couple hours wide for summer views of the milky way. Otherwise, I might as well be living the burbs where straight up is often the only clear view, sometimes not even that!


  • Dave Mitsky likes this

#4 barbarosa

barbarosa

    Gemini

  • *****
  • Posts: 3,178
  • Joined: 11 Apr 2010
  • Loc: 139 miles W of the Awahnee Hotel

Posted 18 July 2021 - 02:29 PM

Find a triangle calculator on the net. Decide what altitude above the horizon you want to be clear, measure or estimate the current or future height of the trees. Solve the right triangle.

 

Here is an example using 20 degrees above the horizon and 60 foot trees.

 

Right Scalene Triangle
Right Scalene Triangle
Side a = 60 (tree height)
Side b = 175.42826
Side c = 164.84865 (base line to trees)

 

You would need to clear the trees out to 165"  from you scope.

 

20 degrees above the horizon is useful altitude but many people would want to go lower.

 

What you might do is download a copy of Stellarium (or other free planetarium software) and set up the location of your prospective site. You can then model the sky for any season and decide if you need a lower or can accept a higher view in particular directions. 

 

Personally I would like a hill top site with an unobstructed view to the horizon. But I foolishly have a home in the burbs, with trees, buildings, hills, various light domes, etc. So for me the best I can do is about 20 degrees, but in most directions 30 gets better results. I could top or remove a few trees and then get a good view directly into a major urban light dome.

 

But if I had a good lot in a darker area the chain saw would get a workout. After all a large clear zone around a house is a sensible defense against fire.


Edited by barbarosa, 18 July 2021 - 02:39 PM.

  • ShaulaB, Astrola72, Richard O'Neill and 1 other like this

#5 PNW

PNW

    Messenger

  • -----
  • Posts: 455
  • Joined: 07 Sep 2017
  • Loc: Lummi Island, WA

Posted 18 July 2021 - 02:40 PM

I used the 45* right triangle. Since the base equals the height, you would have to clear 60' from the tree to get an altitude of 45* above the horizon. I replaced most of my big tree's with 12' bushes.


Edited by PNW, 18 July 2021 - 02:42 PM.


#6 Simcal

Simcal

    Viking 1

  • *****
  • Posts: 607
  • Joined: 01 Oct 2018
  • Loc: Caledon, Ont.

Posted 18 July 2021 - 02:40 PM

I have 1.2 Acres, 150' wide. Backyard is about .4 acre / about 150' x 75'. In the country, so no hydro lines or such.The area is surrounded by 40' pines, 50' beech and the 30' house. While my observatory is centrally located, at 43.83° N. I can't reach NGP during the summer due to foliage.  Objects on the ecliptic are available for about half the night.  I find it a bit claustrophobic and not ideal.  The upside is that I'm well sheltered from the prevailing NW weather and don't feel exposed.

 

Having been here now about 23 years, I'm finding I'm slowly loosing trees to damage or age.  Birch were the first to go, some pines are on the way out, and have lost a few locust.  I can think of 3-4 more that need to come down in the next year or so.  I don't plan to replace them as I feel the property needs to open up a bit.

 

An arborist would be able to provide an assessment of remaining tree growth, and any problem trees which could be culled.  Also consider where the urban light domes are, as you'll likely not be looking that way, much.


Edited by Simcal, 18 July 2021 - 02:42 PM.


#7 Richard O'Neill

Richard O'Neill

    Mercury-Atlas

  • *****
  • Posts: 2,670
  • Joined: 19 Aug 2014

Posted 18 July 2021 - 02:45 PM

BTW, clearing trees can get very expensive.


  • Dave Mitsky, barbarosa and airbleeder like this

#8 kathyastro

kathyastro

    Soyuz

  • *****
  • Posts: 3,529
  • Joined: 23 Dec 2016
  • Loc: Nova Scotia

Posted 18 July 2021 - 02:52 PM

You will want to see down to 30 degrees in the south.  Maybe 20 degrees.  North is less important, because objects in the north come around to the south six months later.  Similarly, east and west objects will be visible a few hours or months later or earlier.  Use a bit of trigonometry to calculate how tall a tree can be in the south, at what distance, to give you the view you want.


  • Jon Isaacs, justfred, sevenofnine and 1 other like this

#9 TOMDEY

TOMDEY

    Voyager 1

  • *****
  • Posts: 10,190
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 18 July 2021 - 03:03 PM

My case was extreme... absurdly so. We were almost solid woods when we moved here 40 years ago. But I ~imagined~ clearing trees for my observatories. So I built the grandiose 24-foot dome... literally in the middle of the woods, and then had the land cleared after the fact. Loggers, skidders, big bull dozer, rock hounding, grading, seeding grass... was not cheap. The cleared area and also some coarse clearing to the south... probably six acres or more of our 16 total. Came out nice!... and then I had to buy a "real tractor" to keep up with the mowing.    Tom

Attached Thumbnails

  • 15 90 Tom's 24-foot dome.jpg

Edited by TOMDEY, 18 July 2021 - 03:05 PM.

  • Dave Mitsky, BRCoz, epee and 3 others like this

#10 barbarosa

barbarosa

    Gemini

  • *****
  • Posts: 3,178
  • Joined: 11 Apr 2010
  • Loc: 139 miles W of the Awahnee Hotel

Posted 18 July 2021 - 03:21 PM

BTW, clearing trees can get very expensive.

It can indeed be expensive particularly when you use a licensed feller and want the waste chipped or hauled away. Things vary by state but I would not use an unlicensed tree service in part because of the liability I would assume in the case of an accident. My neighbor hired a contractor to remove and trim some large trees. I went out to the fence to watch. The safety gear for most of the crew was a green vest, no steel toed boots, no glasses, no bump hats. Some of the would walk directly under a tree that was being limbed. During a break I asked the lead guy for a card and an estimate for removing some sequoias. His card had a license number, his website had the number, the estimate had the number. Licensed and insured! But he wasn't. It was all fake. 

 

I told the neighbor and he shrugged, no worry the company had been recommended by people at church.

 

A year later I obtained three bids from legitimate companies, one sent an arborist and he did not want to remove or top healthy trees. I admire that. One was sky high, impossible. The third was made by the crew leader doing a job up the street. He came over later in the day walked the property, used a laser pointer to clarify where cuts should be made, and the price was only a bit painful. Then he offered plan B they would buck the trunks to shorter lengths and move them to the back of the lot. Deal.

 

They came in and did a safe fast and neat job, leaving me with cords of firewood should I chose to further cut and stack them or a lot of redwood rounds.

 

Then came the revelation. He was moonlighting, the whole crew was moonlighting. When you want more work he said, call this number, don't call the office. 


Edited by barbarosa, 18 July 2021 - 03:29 PM.


#11 edwincjones

edwincjones

    Close Enough

  • *****
  • Posts: 13,895
  • Joined: 10 Apr 2004

Posted 18 July 2021 - 05:47 PM

it is not just your land, but the neighbors land and what they are/will do with it

 

edj



#12 sevenofnine

sevenofnine

    Apollo

  • -----
  • Posts: 1,444
  • Joined: 16 Apr 2016
  • Loc: Santa Rosa, California

Posted 18 July 2021 - 10:18 PM

+1 on kathyastro's recommendation. My tiny fenced backyard only has a view to the South and East from about 30 degrees up. It serves me quite well. Of course I'd like 360 degrees from horizon to horizon but I wouldn't want to live there. waytogo.gif



#13 Tony Flanders

Tony Flanders

    Hubble

  • *****
  • Posts: 19,961
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 19 July 2021 - 06:15 AM

BTW, clearing trees can get very expensive.

In my part of the world it can usually be done more or less for free. You get cleared land; the logger gets to sell the proceeds for firewood or lumber. The more expensive part is removing the stumps and getting the land leveled so that it can be mowed. If you don't do that, you will end up with an unholy mess 5 years later and a brand-new forest 20 years later.

 

As for how much land you need, that depends greatly on how tall trees grow in your part of the world. My impression is that trees in Florida tend to be pretty scrubby, so the Original Poster may be in luck. In my part of the world (New York/New England) the big hardwoods average around 80 feet, and the odd white pine or cottonwood sticks up well above that. The bad news is that they're still getting taller, having started to grow back about 80 years ago, when the Great Depression pretty much wiped out farming as a viable way of life in the hills around here.

 

Anyway, let's say that the trees average 50 feet tall around you. I figure that means you can get away with a square 1-acre clearing -- 210 by 210 feet on a side. You put your observing site 60 feet from the north edge, meaning that it's 150 feet from the trees on the south. You can now see down to arctan(50/60) = 40 degrees to the north, making Polaris just barely visible from my location but not from Florida. And you can see down to arctan(50/150) = 18 degrees to the south, which is just about as low as you can get before the atmosphere starts to degrade your views really badly.

 

If the trees average 100 feet, you need to scale that up to a 4-acre clearing to get the same sky views.

 

Obviously, there are other factors to take into account, such as where to put your house.



#14 alphatripleplus

alphatripleplus

    World Controller

  • *****
  • Moderators
  • Posts: 125,336
  • Joined: 09 Mar 2012
  • Loc: Georgia

Posted 19 July 2021 - 06:43 AM

Before I bought our current home, I was looking for obstructions no more than 20 degrees above the horizon, and less towards the south. I did a bit better than that, particularly towards the south. As others have mentioned, use simple trigonometry to determine the maximum acceptable height of trees at a specific distance from your observing location, and the area you need to clear. 



#15 matt_astro_tx

matt_astro_tx

    Apollo

  • -----
  • Posts: 1,493
  • Joined: 19 Jan 2021
  • Loc: Dallas, Texas

Posted 19 July 2021 - 09:29 AM

How are you guys polar aligning without some kind of view to the north?  I realize we don't need to see the NCP anymore with the tools at our disposal, but we still need some kind of northern view to align, do we not?  (Unless y'all are assuming a mount on a pier that's drift aligned once or something like that.)

 

Please enlighten me, because the property adjacent and to the north of me is owned by an arborist and is completely obscured, leaving me no choice but to image from my driveway, which blocks my view to the south.  I need to sort this out before winter.



#16 Tony Flanders

Tony Flanders

    Hubble

  • *****
  • Posts: 19,961
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 19 July 2021 - 09:36 AM

How are you guys polar aligning without some kind of view to the north?  I realize we don't need to see the NCP anymore with the tools at our disposal, but we still need some kind of northern view to align, do we not? (Unless y'all are assuming a mount on a pier that's drift aligned once or something like that.)


No, it's eminently possible to do a polar alignment without being able to view north of the zenith. Depending on your skill level and the compass quality a magnetic compass properly corrected for magnetic declination will get you within 0.5 to 3 degrees in azimuth, and a digital level will get you within about 0.2 degree in altitude. Then you can drift-align to improve that.

Some Go To mounts also have built-in polar-alignment procedures.

If you're using a tripod, a popular trick is to mark the spot where each foot goes, so that the tripod will be near-perfect as soon as you set it down on those spots.

#17 TOMDEY

TOMDEY

    Voyager 1

  • *****
  • Posts: 10,190
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 19 July 2021 - 11:05 AM

Southern "Bowling Alley" on the meridian... if able to do it on one one's own property. When I was felling trees, tallest one I measured was seventy feet ground to top! 70/tan(6o) = 666 feet (666?! yikes!).  They were growing faster than I could clear and burn them for fire wood. Eventually got loggers in who took the trees but still charged me. And yes, the stumps are by far the toughest part. The BIG bulldozer handles that. It looked like a WWII bomb field in the middle of all that activity.    Tom

Attached Thumbnails

  • 20 Toms 24-foot dome from west hill.jpg


#18 rhetfield

rhetfield

    Surveyor 1

  • *****
  • Posts: 1,901
  • Joined: 14 Aug 2019
  • Loc: Suburban Chicago, IL, USA

Posted 20 July 2021 - 10:23 AM

I never thought I'd need to ask a question such as this, but here we are.

 

I am contemplating purchasing some property for a future home that will hopefully also be useable for astronomy purposes. The lot is fairly good sized (about 2 acres - but it's not square, about 130x550 ft), but it's completely covered in trees, mostly pine, probably about 60 feet tall. Obviously some of this will be cleared out for building, etc.

 

I'm trying to get an idea of how much sky can I see from an open area of a certain size, or looking at it in a different way, how big an open area do I need to be able to see a "reasonable" amount of sky? This is in the Florida panhandle, a little under 30 degrees north latitude.

 

Has anyone dealt with this question? Any ideas are welcome.

Your best bet would be to build a rooftop observatory.  That will help see a bit more above the trees.  Remember that behind the trees is soupy atmosphere anyway.  Forests put out a lot of humidity and haze.


  • RiderRoy likes this

#19 csrlice12

csrlice12

    ISS

  • *****
  • Posts: 28,824
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 20 July 2021 - 10:51 AM

Your best bet would be to build a rooftop observatory.  That will help see a bit more above the trees.  Remember that behind the trees is soupy atmosphere anyway.  Forests put out a lot of humidity and haze.

Yeah, if it's weren't for all that living stuff and atmosphere, this would be a great observing spot...wink.gif


  • barbarosa likes this

#20 Keith Rivich

Keith Rivich

    Mercury-Atlas

  • *****
  • Posts: 2,976
  • Joined: 17 Jun 2011
  • Loc: Cypress, Tx

Posted 20 July 2021 - 11:47 AM

Find some property near J. Isaac's...all you need to do is move a few rocks around and you are all set smile.gif


  • Jon Isaacs likes this

#21 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 94,648
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 20 July 2021 - 03:38 PM

Find some property near J. Isaac's...all you need to do is move a few rocks around and you are all set smile.gif

 

The neighbors to the south have trees. At some points, I can only see down to about 3° above the horizon. There is one spot at about 190° where I can see slightly below the horizon...

 

Starsplitter 22 inch Evening in Boulevard.jpg

 

The 22 inch won't go lower than 5° elevation so use the 16 inch. I had to modify it's base to reach the horizon.

 

Trees mean water and Southern California could sure use some water. Out there, we have a well but mostly it's imported water..

 

Jon


  • Dave Mitsky likes this

#22 gwlee

gwlee

    Mercury-Atlas

  • *****
  • Posts: 2,991
  • Joined: 06 Sep 2015
  • Loc: 38N 120W

Posted 24 July 2021 - 05:05 PM

I am retired and living on an acre of heavily forested mountain ridge near Yosemite NP, so familiar with the various challenges trees can present.  It’s dark here, but the tree dodging problem is acute enough that I am doing most of my observing now with a handheld binocular and a small refractor. As others have said, and I have learned firsthand, clearing trees can be very expensive, and trees on neighboring property, which you can usually do nothing about, often contribute to the problem. 

 

Suggest making a scale drawing of the property to determine your existing and possible future sight lines. Ideally, you want a clear sight line to the horizon in 360*. I would be very happy if I could see above 25*, but I will never get close to that unless/until a major forest fire burns through here.
 


Edited by gwlee, 25 July 2021 - 11:26 AM.


#23 Migwan

Migwan

    Mercury-Atlas

  • *****
  • Posts: 2,792
  • Joined: 24 Jul 2017
  • Loc: Meeechigan

Posted 25 July 2021 - 09:43 AM

Get yourself a cheap angle gauge, attach it to a straight edge such as a ruler and use that to decide what trees have to go.   You can use that to help decide where the best spot on the property is and whether it will do.  Good luck. 



#24 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 98,928
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 26 July 2021 - 11:46 AM

BTW, clearing trees can get very expensive.

I'll say.  I had a dying tree removed from my front yard this morning.



#25 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 98,928
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 26 July 2021 - 11:54 AM

The best dark sky site within about an hour's drive of my home unfortunately has only a very small clearing.  ASH had hopes that it would be developed for astronomy but that has yet to happen.




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.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics