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Special Topic: Life in Martian Meteorites?

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Special Topic: Terrestrial Impact Craters

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Special Topic: Discoveries and Surveys

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Special Topic: Pluto

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“Ice and Stone 2020” participants have undoubtedly noticed that I have often discussed how this-or-that comet or asteroid will be returning to the inner solar system or passing by Earth at some point in the future, and perhaps have wondered how such things are determined. In principle, the processes by which such events are calculated …

Ever since the Italian astronomer Galileo Galilei turned his primitive telescope towards the moon on November 30, 1609 and saw them for the first time, we’ve known that the moon is covered with craters. These come in all sizes, from very large ones several hundred km across down to meter-size and smaller. For a long …

Although they may not be as big a presence in our overall human culture and literature as the moon and the other planets of our solar system are, the “small bodies” of our solar system are nevertheless present. There a number of misperceptions about them, perhaps more so than there are for the planets.  Consider, …

For many people, one of the most fascinating periods of Earth’s natural history is the Mesozoic Era, which spanned from roughly 252 million years ago to 66 million years ago. This period of time is often called the “Age of Dinosaurs,” and indeed these large reptiles were the dominant animals on Earth for well over …

The general topic of meteorites was discussed as a “Special Topics” presentation four weeks ago. The large majority of meteorites that are known are not especially large, being of the order of a few kg in mass; with only a handful of exceptions, even the larger ones tend to have a mass of no more …

One of the most spectacular and awe-inspiring celestial sights is that of a bright, long-tailed comet – a “Great Comet,” the subject of a previous “Special Topics” presentation. On average, these appear about once a decade, and I have been privileged to have witnessed four of them during the half-century I have been observing comets …