The area of Canada where I grew up used to be covered by the Laurentide ice sheet and when it retreated starting more than ten thousand years ago, it left behind tens of thousands (maybe hundreds of thousands) of lakes, especially in the Canadian shield, but also further south. When I was a child I used to look at maps of Canada and marvel at the ingenuity and perseverance of the people who mapped and named thousands of these lakes. Most are probably still unnamed and some even unmapped.
When I got a bit older, I read the Lord of the Rings and became fascinated by the Sea of Rhûn. It seemed unfair that such a large and important body of water in the far east of Christopher Tolkien's maps was barely mentioned in any of JRR Tolkien's writings and nothing at all said about the mysterious large island in the midst of the sea or the forest and mountain range adjacent to it.
A little later, I acquired a 4 and a quarter inch reflector and some basic star charts and I wondered what a map of the Milky Way would look like. I could find nothing however, beyond the usual speculative schematic of a spiral galaxy. I wanted to know where the stars I was seeing through my telescope actually were. I was disappointed to learn that some of the most impressive stars I could see, such as Sirius, were bright only because they were near. I felt like a resident of a remote mountain village, staring longingly at the surrounding peaks and wondering what wonders lay beyond.
I took a survey course on astronomy in university, and I learned the rudiments of astrophysics, including spectral classifications and some of the basic tricks that astronomers use to estimate distances, such as parallax and Cepheid variables. However, I remember no mapping beyond the most general schematic diagram of the Milky Way, including the disk, the bulge and the halo. I wanted something more like the vast and detailed maps of the Canadian wilderness I first saw when I was a child.
It was only in the late nineties that I learned that this kind of detail was possible. On a news site somewhere, I read that parallax data from the Hipparcos satellite had been released and was available for download. I had missed hearing about the Hipparcos project before and was even unaware of the existence of the European Space Agency. But I knew what parallax was from my university course and eagerly downloaded the data. I quickly found the mapping algorithms I needed and soon had an interactive Java mapping program.
At first I was disappointed - it seemed that the stars just went on and on like grains of sand on the beach. I decided to colour them by spectral type and size them by absolute magnitude. Even then I saw no pattern in my first map. I zoomed out to show most of the Hipparcos data. And then I saw them - like a great string of bright pearls. There was a huge clustering of bright class O and B stars a little over 100 parsecs away, in the direction of the constellation Scorpius.
I searched on the Internet for information about this mysterious clustering and found a website run by Leiden University with the answer. (I remember wondering why a university in the cloudy Netherlands would have an astronomy department, not realising that this department was the alma mater of many of the greatest astronomers of the 20th century.)
Having finally heard about OB associations, I searched further on the Internet to learn more about them. The Hipparcos data did not even encompass all of the immediate solar neighbourhood, the Gould belt, and I wanted information far beyond this. It was then that I discovered the Astrophysics Data System (ADS).
And that changed everything.