MARCH 1, 1705: British astronomer Edmond Halley publishes his calculations of the orbits of the comets of 1531, 1607, and 1682, concluding that they are individual returns of the same comet, and that that comet would return in 1758. His prediction turned out to be correct, and the comet has been named in his honor. The story of Halley’s Comet is the focus of next week’s “Special Topics” presentation, and the most recent return of the comet is next week’s “Comet of the Week.”
MARCH 1, 1744: The brilliant Comet de Cheseaux (new style designation C/1743 X1) passes through perihelion at a heliocentric distance of 0.222 AU. Later in the week its multiple tails rising above the horizon formed a dramatic sight in the dawn sky. An image of this comet appears in last week’s “Special Topics” presentation.
MARCH 1, 1950: Fred Whipple publishes his paper, “A Comet Model: The Acceleration of Comet Encke” in the Astrophysical Journal. In this paper Whipple presents his “icy conglomerate” model of a comet’s nucleus – now more commonly known as the “dirty snowball” model – which has now been verified by numerous observations including several spacecraft visits of comets. Whipple’s model, and its verification, is the subject of this week’s “Special Topics” presentation.
MARCH 1, 1984: JPL astronomer Hartmut Aumann and his colleagues publish their paper “Discovery of a Shell Around Alpha Lyrae” in the Astrophysical Journal. Aumann and his colleagues detected excess infrared radiation around the star Vega in data taken with the InfraRed Astronomical Satellite (IRAS) mission, one of the first clear signs of a protoplanetary disk, and first announced their discovery in October 1983. These disks are discussed in both previous and in future “Special Topics” presentations.
MARCH 1, 2020: The 6th-magnitude star HD 153890 in Scorpius (also known as V923 Scorpii) will be occulted by the main-belt asteroid (466) Tisiphone. Most of the predicted path of the occultation lies over open waters of the southeastern Indian Ocean, but the southwestern tip of Western Australia (just south of Perth) is in the path.
MARCH 2, 2004: The European Space Agency’s Rosetta mission is launched from Kourou, French Guiana. After flybys of the main-belt asteroids (2867) Steins in September 2008 and (21) Lutetia in July 2010, Rosetta arrived at Comet 67P/Churyumov-Gerasimenko in August 2014 and went into orbit around it, deployed the Philae lander, and then soft-landed on the comet’s surface at the end of its mission in September 2016. The Rosetta mission is discussed as part of a future “Special Topics” presentation, and Comet 67P is a future “Comet of the Week.”
MARCH 2, 2033: NASA’s Lucy mission is scheduled for arrival at the Jupiter Trojan asteroid (617) Patroclus and its moon Monoetius. The Lucy mission and Trojan asteroids are covered in future “Special Topics” presentations.
MARCH 3, 2021: NASA’s OSIRIS-REx mission is scheduled to depart the near-Earth asteroid (101955) Bennu, which it has been orbiting since late 2018, and begin its return to Earth with collected soil samples. The OSIRIS-REx mission is discussed as part of a future “Special Topics” presentation.
MARCH 6, 1961: Polish astronomer Kazimierz Kordylewski makes his first reported detection of the “Kordylewski clouds” located at the Earth-moon L4 and L5 Lagrangian points. Their existence would remain controversial for several decades but they appear to have been confirmed by a team of Hungarian researchers in 2018. They are discussed in a future “Special Topics” presentation.
MARCH 6, 1986: The Soviet Union’s Vega 1 spacecraft passes approximately 10,000 km from the nucleus of Comet 1P/Halley and returns some of the first direct images of a comet’s nucleus. The 1986 return of this comet is next week’s “Comet of the Week” and the discussion there will include results from the various spacecraft missions.
MARCH 6, 2003: The LONEOS program in Arizona discovers the near-Earth asteroid now known as (196256) 2003 EH1. This asteroid has an orbital period of 5.5 years and travels in an orbit very similar to that of the Quandrantid meteor shower that peaks in early January, and may be the Quadrantids’ parent object (and thus may be an extinct comet nucleus). It does not come within 1 AU of Earth again until 2041 and doesn’t make any close approaches until one of 0.33 AU in December 2052.
MARCH 6, 2009: NASA’s Kepler Space Telescope is launched from Cape Canaveral, Florida. For the next four years Kepler continuously surveyed a field of stars in the constellations Cygnus and Lyra looking for small brightness variations indicative of orbiting planets, detecting to date well over 2000 confirmed exoplanets with a similar number still awaiting confirmation. Kepler also detected significant brightness variations in the star KIC 8462852 (informally known as “Boyajian’s Star”) which are discussed in a previous “Special Topics” presentation.
MARCH 6, 2015: NASA’s Dawn spacecraft arrives at the largest main-belt asteroid, and “dwarf planet,” (1) Ceres and goes into orbit around it. Dawn spent the next 3 ½ years orbiting Ceres from a variety of distances and performed numerous scientific investigations, until the mission was terminated in late 2018 due to a lack of remaining fuel; Dawn remains in orbit around Ceres today. Ceres is discussed in Week 1’s “Special Topics” presentation, and the Dawn mission is among those discussed in a future “Special Topics” presentation.
MARCH 7, 1973: Czech astronomer Lubos Kohoutek discovers a comet, designated Comet Kohoutek 1973f at the time, from Hamburg Observatory in Germany. Comet Kohoutek would not pass perihelion until the following December at the very small heliocentric distance of 0.14 AU and was widely touted as being a potential “Comet of the Century” but, although becoming readily visible to the unaided eye, failed to live up to those projections. It was discussed in last week’s “Special Topics” presentation and is a future “Comet of the Week.”
MARCH 7, 2003: A team of Spanish astronomers led by Jose Luis Ortiz Moreno obtains the first discovery images of the large Kuiper Belt object, and “dwarf planet,” now known as (136108) Haumea, although these images were not noticed and reported until almost 2 ½ years later. Michael Brown’s team reported their discovery of Haumea very shortly thereafter, and there has been some unfortunate controversy as to which team deserves proper credit for its discovery. Haumea and the other “dwarf planets” in the Kuiper Belt are discussed in a future “Special Topics” presentation.