Once upon a time—four point six billion years ago—a thick atmosphere surrounded Mars, perhaps even coloring its sky blue. Once upon a time—three to four billion years ago—an ocean covered thirty percent of the Red Planet’s surface, and deltas formed as water rushed from the land to the sea. Once upon a time—as recently as 2 million years ago—Mars’ volcanoes, the largest in our Solar System, erupted, spilling lava down one hundred kilometer long slopes.

From the Hindenburg to the Goodyear Blimp, airships have for centuries captured our collective imagination and, in recent years, given lift to the popularity of the steampunk genre. But how much do we know, really, about their history and evolution? How did steerable, lighter-than-air craft progress from some crackpot inventor’s dream to the elegant, Victorian technology of literature?

Buddhist interpretations of personhood suggest that we have a misguided understanding of our own internal reality; we perceive ourselves as part of a continuous state of being, moving from day to day and year to year. You, my friend, are a constant. An individual. Self-awareness is self-evident, right?