Pale Blue Dot was written nearly 30 years ago but it still feels relevant, timely, and interesting. Perhaps this is because, on cosmic timescales, 30 years might as well be 0 years. Much of the planetary science in Pale Blue Dot is out of date (naturally, given the pace of scientific progress. For example, we have discovered thousands of brown dwarf stars now, while the existence of brown dwarf stars was still largely theoretical when Sagan was writing.
Despite the outdated science, the book felt fresh and engaging largely because of Sagan’s talent for imparting the unending joy and wonder the Universe contains — reading his descriptions of the Solar System and humanity’s potential future traveling the stars made me wish I hadn’t been too scared of math to pursue a degree in astronomy instead of political science.
While much of the book was a joy to read, some of the dangers we pose to ourselves (and the rest of life on Earth) that were obvious then are still there, with no real progress made. Global warming was an obvious, real threat in 1994, well known to the scientific community and to policy makers. 28 years later, we have made no appreciable progress towards stopping global warming. In the United States, corporate interests empowered by far right science deniers make it feel unlikely that we will make any real progress on this front until it is far too late. Sagan also assumed that future manned space flight would be a joint effort by governments around the world. Writing from 1994, he had no way of knowing that the richest men on Earth would fund space exploration from their own fortunes because they have nothing else to spend their money on. Sagan rightly noted that profit-seeking could fuel space exploration, but I suspect he did not imagine a world so unequal that a couple of rich guys would start their own space companies for bragging rights.
In the last few chapters, Sagan describes a potential future for humans, first settling other worlds in the Solar System and then, far into the future, becoming something like the hunter gatherers that we were thousands of years ago, moving from world to world, leaving the Solar System and migrating slowly through the Oort Cloud and, eventually, reaching new galaxies. As our descendents travel from world to world, they would, at some point, no longer be human in any meaningful sense of the world. They would build cultures and societies far more advanced than ours is, but, hopefully, Sagan imagines that those far future travelers would remember their origins on our humble, unremarkable world and keep the Earth in their cultural memories. Whether we will last long enough as a species to make it off the Earth permanently seems less likely by the day, but hoping for a better future can inspire folks to create a more just and thoughtful present.