Revisiting the Past
This week Mark and I are releasing a fulldome show version of the very first Loch Ness Productions planetarium show I ever wrote, called Light Years from Andromeda. It tells one of the most important stories in astronomy and cosmology — that of cosmic distance, and humanity’s quest to understand the universe. It is, as we say on the show’s Web page touting the show, “a journey of epic proportions across space and time.”
It seems particularly appropriate to talk about it today, with the release of a new, more precise value for the Hubble Constant. That constant is one of the numbers astronomers use to determine the expansion rate of the universe. Knowing that expansion rate helps us also determine other factors like the size of the universe and just how old the universe really is. But, the root of all this knowledge is cosmic distance.
Distance in the universe is important to understand, and it is measured by using “standard candles” in the darkness. The standard candles are usually specific types of supernova explosions and, in particular, a type of pulsating star called a Cepheid variable. These pulsate with a regular rhythm and they are found in every galaxy we’ve seen so far. You can use the observations of those candles to derive distances across the cosmos.
In Light Years from Andromeda, we focus on a distance that most people have heard of, even if they aren’t up on the latest in cosmology: the light-year. It’s the distance that light travels in a year at a speed of roughly 300,000 kilometers per second. We wanted to bring that figure into some kind of reality for people, so I decided to take them out to the Andromeda Galaxy, which lies some 2.5 million light-years away. We begin the show there, some 2.5 million years ago, and we bring people back home to the Milky Way, across all that time and space at the speed of light. Along the way we discuss human history set against that travel time. And, when we arrive at Earth, we learn about light-speed and the way that we can use light to measure cosmic distances. It’s really a simple concept and a simple story to tell. And, it’s been very satisfying to see the show come to life in the new fulldome medium, where we really CAN fly from one galaxy to another and take in the breathtaking beauty of the cosmos. And, to have it come out now, when the precision of the Hubble Constant is even better than before — well, it just sends chills up my spine. These are the times that make my day as a science writer!
(Check out the trailer for the show below.)