After all the hoopla associated with Jupiter’s publicity stunt died down, planetary scientists got down to the business of analyzing their data. Simulations of the aftermath of a comet or asteroid impact had been available for years and in July 1994 many of the predictions were confirmed, albeit some more dramatically than expected. The timing of the event was almost as if to remind us to take more seriously what we have been thinking and talking about for some time. Putting aside for a moment the implications for life on earth had something similar happened here, let’s look at some of the things that were learned. Argument continues as to what actually hit Jupiter, a comet or asteroid. When the Space Telescope Science Institute sent out a press release on September 29, 1994, entitled “Hubble Observations Shed New Light on Jupiter Collision,” we were led to expect an answer. The introduction gave us further hope: “Was it a comet or an asteroid?” But the institute didn’t have the answer. Its observations slightly favored a cometary origin, but the asteroid possibility still could not be ruled out. Comets are mostly icy, or so we like to think, and asteroids are mostly rocky or metallic, or so we like to think. When you really get down to it, this business of the difference between comets and asteroids has launched a new cottage industry within astronomical circles. A more recent hint that a comet was involved came from observations made from on board the Kuiper Airborne Observatory, an airplane that carries a beautiful infrared telescope high above most of the water vapor in the atmosphere where it can then see more clearly. Ann Sprague and Donald Huntern from the University of Arizona and their colleagues found evidence for water minutes after two of the fragments smashed into Jupiter. The water signature, a spectral line, indicated it was at a temperature of 500 kelvins (degrees above absolute zero, or about 230 Celcius), much hotter than Jupiter’s usual 200 kelvins (-73 Celcius). Although they could not rule out that the water originated deep in Jupiter’s clouds, the way it came and went over a period of 20 minutes suggested that it was liberated by the impact and was part of a cometlike object.
The impact of optical comb stability on waveforms generated via spectral line-by-line pulse shaping