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History


AUGUST 3, 1963: U.S. Government sensors detect an airburst explosion near the Prince Edward Islands off the southern coast of South Africa. At first it was thought that this was caused by a clandestine nuclear device tested by that nation, but later study revealed that it was caused by an incoming small stony asteroid. Airburst …

JULY 28, 2014: The Pan-STARRS program in Hawaii discovers the centaur designated as 2014 OG392; it has an orbital period of 42.8 years and will pass perihelion in November 2021 at a heliocentric distance of 10.0 AU. An observational analysis published earlier this year indicates sustained cometary activity, however, this report was published too late …

JULY 19, 2009: An unknown object, most likely an asteroid a few hundred meters across, impacts Jupiter, leaving a black “scar” in Jupiter’s atmosphere that persists for the next one to two weeks; the “scar” was first noticed by amateur astronomer Anthony Wesley in New South Wales. The “scar” was reminiscent of those produced by …

JULY 12, 2001: American astronomer Gary Melnick and his colleagues publish their discovery of water vapor around the old, evolved star CW Leonis, suggesting the presence of exocomets around that star. The subject of exocomets, including the importance of this discovery, is discussed in a previous “Special Topics” presentation.  JULY 12, 2126: Comet 109P/Swift-Tuttle, the …

JULY 5, 1687: British physicist Isaac Newton publishes his Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), usually known as the Principia, wherein he lays out what is now known as his Law of Universal Gravitation. Part of Newton’s work in the Principia was based upon his calculations of the Great Comet of 1680 …

JUNE 28, 1911: A meteorite falls to the ground near the village of El Nakhla El Bahariya, Egypt. The Nakhla meteorite was one of the first-known meteorites determined to have come from Mars. A fragment of the Nakhla meteorite supposedly struck and killed a dog, although there has been no independent confirmation of this. “Martian …