Taking astronomical images can be a very rewarding process—in part because of the gorgeous images you take, but also in part because of all the obstacles that can prevent you from observing the skies. We can protect our telescopes in buildings during the day to keep them clean and dry, but when night comes and we open the domes, the weather becomes our worst enemy. My most recent observing run was plagued by all of these problems, and it was a constant battle to try to collect data.
The most common obstacle is clouds. Optical telescopes, just like the human eye, cannot see through a cloud. It doesn’t matter how big the telescope is, all you see is gray static in your image. Sometimes you are lucky enough to observe at a telescope situated on top of a mountain that is above any clouds. However, the telescope most IU astronomers use–the WIYN telescope in Arizona–is not quite this high. So instead, while you wait for the clouds to clear, you can busy yourself with other work—for example, I recorded a video for a summer class I am teaching.
Similar to a shaky hand with a still camera, if your telescope moves in high wind, your images are blurred and sometimes have streaks across them. Occasionally the streaks look cool, but they aren’t good for data collection. Well built telescopes have a higher tolerance for wind, and if you are looking at a certain part of the sky, the telescope dome might block most of the wind. But sometimes the wind can be too fierce even for that trick, and you have to close down. Again, you work on something else—for me, writing a story while chatting to the telescope operator, both hoping the winds will die down.
Although it seems silly that humidity in the air could damage your instrument, the electronics are sensitive and must be kept in pristine conditions. High humidity can be like dumping them in a pool (generally not encouraged). Humidity can also lead to condensation on windows in the system, and then you end up taking images of the sky through water droplets, which ruins your image. This can be especially difficult when you are trying to measure many small bright spots on your image because they end up blurred together into one big blob. So again, you occupy yourself with yet another task—I marathon read a book in one night, while occasionally glancing up at the humidity chart and wishing it would dip below the humidity threshold.
The obstacle that plagued my most recent observing run was dust. Dust gets on your mirror and scatters the light you are trying to study. Once again, this leads to ugly images and poor science. I’d love to give a clever analogy here, but it’s really just like trying to take pictures in a dust storm. At one point, the dust was so thick that you could shine a flashlight into the sky and clearly see the beam of light illuminating all the dust in the air. Most telescopes are in dry locations to avoid high humidity, but if it’s too dry, wind during the day stirs up the dust and leads to closure. I’m sure you can guess what’s next—I watch random documentaries and stand-up comedy on Netflix in an effort to stay awake, even though I know it will likely not clear. Not this night and not the next….
There are very few perfect places on earth to put a telescope, and yet astronomers have already put our very best instruments there. The rest of us settle for slightly worse locations, and hope that luck is in our favor. Yet even the telescopes in perfect places like Hawaii pale in comparison to telescopes in space. Above our Earth’s atmosphere, there are no clouds, no wind, no humidity, and no dust—except for the dust that astronomers study.
Despite all of these obstacles, and nature itself fighting against us, we do have clear nights when everything works in our favor. And on those nights the glory of the universe is revealed. This is when we can conduct our science, making the late nights worth it. We might not get perfect weather every night, but over the course of a career it balances out. As long as the science gets done, and I am still able to travel to exciting locations, I’ll accept the few nights when the weather wins.
For additional insight into what remote observing is like, check out my video blog of this same observing trip: