Seeing is Believing

My nomadic telescope installation during a cool early spring evening in central California awaiting nightfall for some bortle 2-3 skies.

What is your view to the east, south, north, and west? If you are in the northern hemisphere, can you see Polaris? Are there any light domes along the horizon that you need to consider? What about atmospheric conditions? What I can I do to mitigate air turbulence?

Whether you are traveling to a remote dark site or selecting a location for you permanent observatory building, there are many viewing considerations to take into account. Sight lines, seeing, light pollution, all contribute to what will ultimately be your enjoyment of the observing or photographing the night sky. In the northern hemisphere, selecting a site that has a view toward Polaris seems like the obvious choice, but sometimes it may not be. With software polar-alignment routines, there is no longer a need to see Polaris. Other factors such as light pollution or your overall view of the sky may have a larger impact on where you locate your telescope or observatory. It may seem obvious however, if in one location, you can see polaris but you can’t see a vast majority of the eastern sky or southern sky because there are tall trees or your neighbor’s roof is in the way, you may want to consider a different location in order to gain a view to those areas of the sky.

Another factor is seeing. In his book The Astrophotography Manual, Chris Woodhouse describes astronomical seeing as, “an empirical measure of the optical stability of our atmosphere.” He goes on with his thought indicating, “ Turbulence causes rapid, localized changes in air density and parallel beams are deviated through refraction.” Essentially, it is this air turbulence that makes stars twinkle. Aside from selecting an observatory site as a whole, one of the most important factors that you can control in order to obtain the best possible seeing is by understanding how the treatment of the ground surfaces immediately around your telescope and observatory building. Materials and surfaces such as concrete, gravel, bare dirt or soil, pavers, and other similar hard and low conduction type of materials, etc, all act as heat syncs - they absorb and slowly radiate heat. It is this slow radiation of heat that causes localized turbulence around your telescope. Therefore when selecting a site or choosing surface materials to place around your observatory building you should avoid areas with large expanses of hard low conduction materials which absorb and radiate very slowly. Instead try to use ground cover materials that are naturally exhibit higher conductivity, that is ones that radiate heat quickly. These are materials that when left sitting out in the light of the hot sun for many hours during the day do not feel hot to the touch such as native grasses (these tend to be more drought tolerant as well).

Finally, the astronomer’s worst enemy - light pollution - may have the greatest impact on selecting a location for your observatory or traveling telescope installation. It is no coincidence that LED lights have made a huge impact on our night sky as a whole. Just compare David Lorenz’s latest light pollution map with his previous maps and you can see their impact. Much of the developed world is now blanketed in the soft glow of light at night. And sadly this isn’t going away. But David’s map can be useful to those looking for a place to observe. Seek out those places that exhibit the least amount of pollution, understand where there may be a light dome in the desired direction of your view and most importantly, don’t contribute to this alarming problem, turn off lights you are not using at night. As an architect, I try to limit the amount of light that my building designs contribute.

Many architects, and lighting designers alike, have no concern about adding another light to their particular design as they are mostly ignorant of the impact. If you are going to select a professional architect to help you with your dreams of building the ultimate observatory, consider downloading our STELLARSPACES™ Planning Pack to learn how we may be able to help you.