This Week in History: May 31-June 6

Ice and Stone 2020: Week 23 Content

MAY 31, 2020: Comet ATLAS C/2019 Y4 will pass through perihelion at a heliocentric distance of 0.25 AU. A previous “Comet of the Week,” Comet ATLAS initially showed potential for becoming a bright object, but it now appears to have all but disintegrated as it has approached perihelion. It is traveling in the same orbit as the Great Comet of 1844 and is almost certainly a trailing component of that comet; this and other comet “pairs” and “groups” are discussed in a future “Special Topics” presentation. 

JUNE 1, 1995: The “Near-Earth Objects Survey Working Group,” a special commission chartered by the U.S. Congress and led by planetary geologist Eugene Shoemaker, issues its report to Congress and to NASA. Among its major recommendations is the establishment of comprehensive sky surveys to search for potentially threatening near-Earth objects and identify them well in advance. The results of these surveys are discussed in a previous “Special Topics” presentation, and the surveys themselves are discussed in a future “Special Topics” presentation. 

JUNE 2, 1822: German astronomer Carl Rumker, then residing at Parramatta, New South Wales, recovers the comet now known as 2P/Encke based upon a prediction made by German mathematician Johann Encke. This was only the second periodic comet to be recovered based on a prediction, and the comet was subsequently named after Encke. Comet 2P/Encke returns to perihelion later this month and is a future “Comet of the Week.” 

JUNE 2, 1858: Italian astronomer Giovanni Donati discovers a comet from Florence Observatory. Later that year Comet Donati became a spectacular naked-eye object, and it is a future “Comet of the Week.” 

JUNE 2, 2018: The Mount Lemmon survey based in Arizona discovers a tiny asteroid, no more than a few meters across, designated 2018 LA. Eight hours later 2018 LA entered the earth’s atmosphere above Botswana and disintegrated, creating a bright fireball in the process. A few meteorites have subsequently been identified in Botswana. 2018 LA and a few similar objects are discussed in a future “Special Topics” presentation. 

JUNE 3, 1861: Comet Thatcher 1861 I (new style: C/1861 G1), the parent comet of the Lyrid meteor shower, passes through perihelion at a heliocentric distance of 0.921 AU. 

JUNE 3, 1966: American geophysicist Henry Faul publishes his paper “Tektites are Terrestrial,” wherein he demonstrates that the rocks called “tektites,” despite their similar physical appearances to meteorites, are in fact terrestrial in origin, although they are created by soil and sediment heated up due to meteorite impacts. Tektites and their relationship to meteorites are discussed in a previous “Special Topics” presentation. 

JUNE 3, 2013: The centaur (10199) Chariklo occults a 13th-magnitude star in Scorpius. Before the actual occultation itself, the star briefly disappeared and reappeared twice, and did the same thing after the occultation, revealing that Chariklo possesses two very thin rings – the only centaur known to do so. Centaurs, and results like these obtained from observations of occultations, are both subjects of previous “Special Topics” presentations. 

Luis Walter Alvarez (left) and his son Walter Alvarez (right) at the K-T Boundary in Bottaccione Gorge, near Gubbio, Italy. Courtesy of Lawrence Berkeley Laboratory.

JUNE 6, 1980: The father-and-son team of Luis and Walter Alvarez publish a paper wherein they show that sediments from the end of the Cretaceous Period 66 million years ago are heavily enriched with the metal iridium, which is very rare on Earth but somewhat abundant in asteroids and comets. They then propose that the impact of such an object at the end of the Cretaceous Period was responsible for the mass biological extinction event at that time that killed, among many other species, the dinosaurs. The “K-T event,” as this has come to be called, is the subject of this week’s “Special Topics” presentation. 

More from Week 23:

Comet of the Week    Special Topic    Free PDF Download    Glossary

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Author

  • Alan Hale

    Alan Hale was born in Tachikawa, Japan (as the son of a U.S. Air Force officer) but moved with his family later soon after to Alamogordo, New Mexico, where he spent his childhood years. Hale entered the Navy and graduated from the U.S. Naval Academy with a Bachelor’s Degree in Physics After leaving the service, he began working at the Jet Propulsion Laboratory on the Deep Space Network. While at JPL he was involved with several spacecraft projects, most notably the Voyager 2 encounter with the planet Uranus. Following that encounter, Hale left JPL and enrolled at New Mexico State University. He earned his Master’s Degree and then his Ph.D.. His thesis paper has become one of the seminal papers in early exoplanet research, with over 200 citations to date. He worked at the New Mexico Museum of Space History as its Staff Astronomer and Outreach Education Coordinator, before founding the Southwest Institute for Space Research (now known as the Earthrise Institute). He has developed and taught astronomy-related educational activities at the university level. Hale’s research interests include the search for planets beyond the solar system; stars like the sun; minor bodies in the solar system, especially comets and near-Earth asteroids; and advocacy of spaceflight. He is primarily known for his work with comets, which has included his discovery of Comet Hale-Bopp in 1995. In recent years he has worked to increase scientific collaboration between the U.S. and other nations, including Iran, Zimbabwe, and Lebanon. Hale lives in the Sacramento Mountains outside of Cloudcroft, New Mexico with his partner Vickie Moseley. He has two sons, Zachary and Tyler, both of whom have graduated from college. On clear nights he can often be found making observations of the latest comets or other astronomical phenomena.

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