My first astronomy job came when I left high school and worked for six months at the Royal Greenwich Observatory, at that time located at Herstmonceux Castle in Sussex. After a math degree at Churchill College, Cambridge and a summer job at Royal Observatory, Edinburgh, I began a Ph.D. at the Institute of Astronomy at Cambridge (the real Cambridge, I mean). This turned out to be a work of fiction about stars that never existed and predicted a submillimeter background radiation that was later discovered and shortly thereafter retracted. I decided it was time to work on things one could really observe, and went to do a postdoc at Jodrell Bank. After a brief flirtation with the microwave background I got interested in the physics of quasars and have been stuck trying to figure them out ever since. I came to CfA in 1988 as a postdoc, escaped to Huntsville, Alabama in 1991 but the lure of Harvard Square was too strong and I've been back here since 1992. Most recently I've been studying quasars and nearby galaxies with the Chandra X-ray Observatory and helping the development of Chandra's CIAO data analysis system.
My Erdos number is 5
You can also read a more formal bio.