Lost minor planet

This happens if the orbital elements of a minor planet are not known accurately enough, typically because the observation arc for the object is too short, or too few observations were made before the object became unobservable (e.g. too faint due to increasing distance, or too close to the Sun to view at night).

[2] Some lost minor planets discovered in decades past cannot be found because the available observational data is insufficient for reliable orbit determination.

[6] The number of asteroids that were only observed once and not re-observed grew throughout the 19th and 20th centuries, but improved telescopes, searches, and detection techniques led to resolution of most of these cases between 1970 and 2000.

[7] Leif Kahl Kristensen at the University of Aarhus rediscovered 452 Hamiltonia and 1537 Transylvania, along with numerous other small objects, in 1981.

[16] At the time these results were published, only the nine numbered minor planets 330 Adalberta, 473 Nolli, 719 Albert, 724 Hapag, 843 Nicolaia, 878 Mildred, 1009 Sirene, 1026 Ingrid, and 1179 Mally (below) had remained unobserved since their discoveries:[16] Other notable recoveries Below are some notable asteroids that have been discovered during the 20th century but are still lost as of 2025[update].

More than 700,000 minor planets have been observed, many of which must be considered lost due to insufficient observational data. [ 1 ] [ 2 ]
The orbits of kilometre class NEAs are generally well known, though a few have been lost. However, large numbers of smaller NEAs have highly uncertain orbits [ 4 ]