I don’t think any of us were driven by particular scientific questions. We were driven by the fact that there was this new technology, that we could use to probe all kinds of questions. Harold Johnson deserves special mention, though. He really started infrared astronomy – was Frank Low’s mentor. His approach was a little different. I guess it’s fair to say he had a vision of some scientific questions he was going to work on, and working in the infrared would help him with that. Probably that is because he was the only person involved at that early stage with a degree in astronomy instead of physics. Progress in infrared astronomy thus came from blending different approaches.

We, on the other hand, just realized there were a lot of neat things we could find. The most outstanding example, way before I started, was with Kuiper’s 61-inch telescope. By the time it got commissioned, Harold Johnson and then Frank Low had joined Kuiper’s staff. One month after the telescope had seen first light, Frank hauled a very crude infrared light-measuring instrument to the telescope. He took measurements of Jupiter and discovered a fundamental thing about the way giant planets work: Jupiter emits more light by a factor of two than it absorbs from the Sun, implying that there is an internal source of heat not realized previously.

Our group later found that galaxies emit a lot of energy in the infrared that’s an indication of hidden, sometimes very dominant, amounts of star formation. In these galaxies starlight is heating up the dust and making it glow in the infrared. Often, there was little hint from the visible that anything was going on in the galaxies. We also found that active galactic nuclei are, again, strong infrared emitters due to the discs of heated gas and dust that are spinning around their black holes. We know a lot about these black holes now; but we didn’t know it then, so some rather fanciful ideas sprang up to explain this.