JANUARY 5, 2005: The Kuiper Belt object now known as (136199) Eris is discovered by Mike Brown, Chad Trujillo, and David Rabinowitz on images taken in October 2003. Eris travels around the sun in a moderately-inclined and moderately eccentric orbit with a period of 558 years; it has one known moon (Dysnomia) and turns out to be slightly smaller than, but slightly more massive than, Pluto. When Eris’ discovery was announced in August 2005 it brought to a head the matter of how to classify Pluto and other objects like it such as Eris; the following year these objects were assigned to the newly-created category of “dwarf planets.” These objects are discussed in future “Special Topics” presentations.
JANUARY 5, 2020: The main-belt asteroid (1203) Nanna will occult the 7th-magnitude star HD 222455 in Pisces. The predicted path of the occultation crosses northwestern Mexico and central Texas and Louisiana.
JANUARY 6, 1978: Paul Wild at the University of Bern in Switzerland discovers the comet now known as 81P/Wild 2. This comet, which was last week’s “Comet of the Week,” was found to have been perturbed into an inner-solar system orbit following a very close approach to Jupiter in 1974, and was the destination of NASA’s Stardust mission which successfully returned samples to Earth in 2006.
JANUARY 6, 2010: The LINEAR program in New Mexico discovers what initially appeared to be a comet and which received the preliminary designation of P/2010 A2 and which is now formally known as 354P/LINEAR. The object was found to be traveling in a near-circular orbit within the inner main asteroid belt and is now believed to be the result of a collision between two asteroids (with the “tail” being the trail of dust debris following the collision). “Active asteroids” are the subject of a future “Special Topics” presentation.
JANUARY 6, 2019: NASA’s OSIRIS-REx mission, in orbit around the near-Earth asteroid (101955) Bennu, detects the first of many “plume eruptions” of material off Bennu’s surface. These events make Bennu an “active asteroid” – the subject of a future “Special Topics” presentation – and are consistent with the presence of hydrated clays on Bennu’s surface, suggesting in turn that it might be a fragment of what had once been a comet.
JANUARY 6, 2020: The main-belt asteroid (1400) Tirela will occult the 6th-magnitude star HD 39051 in Orion. The predicted path of the occultation crosses the southern U.S. (Louisiana, Texas, New Mexico, Arizona, and southern California, including just north of Los Angeles), the northern Pacific Ocean, the northern part of the Japanese island of Honshu, North Korea (just north of Pyongyang), and northeastern China (just south of Beijing).
JANUARY 7, 1976: From Palomar Observatory in California, Eleanor Helin discovers a fast-moving asteroid now known as (2062) Aten. This was the first known asteroid to have an orbital period of less than one year, and is the prototype of what are now called the “Aten” asteroids. The Aten asteroids and the other classes of near-Earth asteroids constitute this week’s “Special Topics” presentation.
JANUARY 7, 1985: The National Space Development Agency – now the Japanese Aerospace Exploration Agency, or JAXA – launches the Sakigake mission from what was then called the Kagoshima Space Center on the island of Kyushu. On March 11, 1986 Sakigake made a distant flyby of Comet 1P/Halley (7.0 million km).
JANUARY 8, 2014: A 90-centimeter-wide object enters Earth’s atmosphere near a point above Manus Island in Papua New Guinea and disintegrates as a bright fireball. Analysis of the available data by Avi Loeb and Amir Siraj at Harvard University (and announced in April 2019) suggests that the object had an unusually high pre-entry orbital velocity (almost 60 km/sec) which in turn suggests that it was not gravitationally bound to the solar system and thus may be interstellar in origin. At this time these findings have not been confirmed.
JANUARY 8, 2025: The large near-Earth asteroid (887) Alinda will pass 0.082 AU from Earth – the closest approach it has made since its discovery in 1918 – and should reach 9th magnitude.
JANUARY 8, 2020: The discovery of asteroid 2020 AV2, found on January 4, 2020 by the Zwicky Transient Facility survey based in California, is announced by the Minor Planet Center. 2020 AV2 is tied for the shortest orbital period among known asteroids, and is the first-known asteroid with an orbit that lies entirely within the orbit of Venus. Its discovery is discussed within a Special Addendum to this week’s “Special Topics” presentation.
JANUARY 9, 1992: David Rabinowitz with the Spacewatch program in Arizona discovers a slow-moving asteroid, now known as (5145) Pholus; it was found to have an orbital period of 92 years and a perihelion distance of 8.8 AU. Pholus was only the second-known such object, following the discovery of (2060) Chiron in 1977, but many more such objects have been discovered since then. Collectively these objects are referred to as “Centaurs,” and they are covered in a future “Special Topics” presentation.
JANUARY 10, 2002: Comet 201P/LONEOS, discovered in September 2001 by the LONEOS program in Arizona, passes only 0.014 AU from Mars. This was the closest-known cometary approach to Mars at the time; that record has now been broken with the approach of Comet Siding Spring C/2013 A1 in October 2014 (and which is a future “Comet of the Week”).
JANUARY 10, 2020: The main-belt asteroid (16054) 1999 JP55 will occult the 6th-magnitude star 50 Leonis. The predicted path of the occultation crosses central Honshu in Japan, northeastern China, central Russia, northern Finland, and north-central Sweden.
JANUARY 11, 1972: Elizabeth Roemer and Larry Vaughn recover the long-lost periodic comet 9P/Tempel 1. The comet, discovered in 1867, had not been seen since 1879, with the exception of a tentative image obtained by Roemer in June 1967 which was confirmed by the 1972 recovery. It is now safely “on-board” and was the destination of NASA’s Deep Impact mission in 2005 and visited again by the Stardust mission in 2011; it is a future “Comet of the Week.”
JANUARY 11, 2018: The Arkyd-6 satellite, designed and built by the private company Planetary Resources – now a subsidiary of ConsenSys – is launched from the Satish Dhawan Space Centre in India. Arkyd-6 is a technology testbed for future missions that will hopefully begin to carry out Planetary Resources’ mission of resource extraction from asteroids. The subject of asteroid and comet mining is the topic of a future “Special Topics” presentation.
JANUARY 11, 2020: Comet 289P/Blanpain will pass 0.090 AU from Earth. The comet was lost from the time of its original discovery in 1819 until 2003 when it was re-discovered as an apparent asteroid, and even this identity wasn’t confirmed until 2013. It is traveling northeastward through Cassiopeia and may possibly become bright enough for visual observations; if it does the Comet Resource Center will carry updated information about it.