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The discovery of the planet Uranus by British astronomer William Herschel in 1781 essentially doubled the size of the then-known solar system. During the years after Uranus’ discovery astronomers began to notice small discrepancies in its orbital motion, and at least two individuals – a young British astronomer named John Adams, and a French mathematician, …

The majority of what we know about the various planets and many of the other objects in our solar system has come from spacecraft missions sent to those bodies. Even with the best telescopes here on Earth many of these objects are little more than points of light in the sky, and it was only …

During the early morning hours on Tuesday, June 30, 1908, at around 7:17 A.M. local time, “something” entered the earth’s atmosphere near the Pacific coast of Asia, traveling northwestward. A few km above the surface of a largely uninhabited region of central Siberia, near the Stony Tunguska River some 90 km north-northwest of the village …

“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, …