This Week in History: May 24-30

Ice and Stone 2020: Week 22 Content

MAY 24, 1981: American astronomer Harold Reitsema and his colleagues, observing from Arizona, detect a possible moon of Neptune during an apparent occultation of a background star. This object was confirmed by Voyager 2 during its flyby of Neptune in August 1989 and is now known as Larissa and designated as Neptune VII. 

Two views of Larissa, a dark, irregularly shaped moon of Neptune discovered in 1989 by Voyager 2. Courtesy of NASA/JPL.

MAY 24, 2001: Comet LINEAR C/2001 A2, the first relatively bright naked-eye comet of the 21st Century, passes through perihelion at a heliocentric distance of 0.779 AU. It is a future “Comet of the Week. 

MAY 25, 44 B.C.: According to approximate orbital calculations, the comet known as “Caesar’s Comet” (formally designated C/-43 K1) passes through perihelion at a heliocentric distance of 0.22 AU. It is this week’s “Comet of the Week.” 

MAY 27, 1894: Arctic explorer Robert Peary, together with Hugh Lee and an Inuit guide named Tallakoteah, locate what is now known as the Cape York meteorite on an island off the northwestern coast of Greenland. This meteorite is now on display at the American Museum of Natural History in New York, and it along with other large meteorites that have been found on Earth’s surface constitute the subject of this week’s “Special Topics” presentation. 

MAY 27, 2020: Comet SWAN C/2020 F8 will pass through perihelion at a heliocentric distance of 0.430 AU. This comet, which was discussed in a previous “Comet of the Week” presentation, was dimly visible to the unaided eye from the southern hemisphere late last month and early this month, and presently is detectable from the northern hemisphere albeit at a small elongation from the sun. Current information about it can be found at the Comet Resource Center. 

Mariner 9 was the first probe to enter orbit around another planet. Courtesy of NASA/JPL.

MAY 30, 1971: NASA’s Mariner 9 mission is launched from Cape Canaveral, Florida, towards Mars. Mariner 9 became the first spacecraft to orbit Mars, and in addition to discovering numerous important features on Mars’ surface also returned the first clear images of Mars’ moons Phobos and Deimos. 

The interplanetary spacecraft was launched onboard an Atlas-Centaur rocket on May 31, 1971. Courtesy of the US Air Force.

More from Week 22:

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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