Astronomy Fundamentals: The Last Trillionth of the Journey

As stargazers, we look out across space at objects floating in what is mostly vast emptiness. The light we see travels at its breathtaking speed through a vacuum, only now and then perhaps encountering some wisps of gases and dusts. To an observer on our Moon, or to the Hubble or Webb space telescopes, a star that’s 5 light years away can be resolved as if it was much closer. But to reach us down on Earth’s surface, the light from celestial objects has to also traverse the disruptive chaos of our planet’s atmosphere. That last trillionth* of its trip can inflict a lot of damage on our ability to see the Universe. (*~50km to the top of the stratosphere is about a trillionth of 5.25ly; or an even smaller fraction of the distance to another galaxy!) For the Tuesday, February 18th Astronomy Fundamentals Program, long-time observing enthusiast Drew Carhart will lead us through a practical, observer-oriented look at what goes wrong in those last few kilometers; how do atmospheric conditions affect what you might see tonight? What parts of “weather” matter to the stargazer? How and why does skyglow (light pollution) vary from place to place, and hour to hour? How does one measure and predict these things? Come and learn that it isn’t just your imagination that the sky didn’t look quite as good last night as it did a week ago, or that you can’t judge the quality of an observing site from just one visit. And, hopefully, pick up some pointers that will help you see the Universe a little more sharply!