Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery.
Approximately 47% of the more than 1,100,000 known minor planets[2] remain provisionally designated, as hundreds of thousands have been discovered in the last two decades.
[3] The current system of provisional designation of minor planets (asteroids, centaurs and trans-Neptunian objects) has been in place since 1925.
It superseded several previous conventions, each of which was in turn rendered obsolete by the increasing numbers of minor planet discoveries.
A modern or new-style provisional designation consists of the year of discovery, followed by two letters and, possibly, a suffixed number.
[4] For example, the provisional designation 1992 QB1(15760 Albion) stands for the 27th body identified during 16-31 Aug 1992: This scheme is now also used retrospectively for pre-1925 discoveries.
It soon became apparent, though, that continuing to assign symbols was impractical and provided no assistance when the number of known minor planets was in the dozens.
Johann Franz Encke introduced a new system in the Berliner Astronomisches Jahrbuch (BAJ) for 1854, published in 1851, in which he used encircled numbers instead of symbols.
The new system found popularity among astronomers, and since then, the final designation of a minor planet is a number indicating its order of discovery followed by a name.
Even after the adoption of this system, though, several more minor planets received symbols, including 28 Bellona the morning star and lance of Mars's martial sister,[9] 35 Leukothea an ancient lighthouse[10] and 37 Fides a Latin cross ().
[11] According to Webster's A Dictionary of the English Language, four more minor planets were also given symbols: 16 Psyche, 17 Thetis, 26 Proserpina, and 29 Amphitrite.
Three centaurs – 2060 Chiron, 5145 Pholus, and 7066 Nessus – and the largest trans-Neptunian objects – 50000 Quaoar, 90377 Sedna, 90482 Orcus, 136108 Haumea, 136199 Eris, 136472 Makemake, and 225088 Gonggong – have relatively standard symbols among astrologers: the symbols for Haumea, Makemake, and Eris have even been occasionally used in astronomy.
[14] Several different notation and symbolic schemes were used during the latter half of the nineteenth century, but the present form first appeared in the journal Astronomische Nachrichten (AN) in 1892.
In 1893, though, increasing numbers of discoveries forced the revision of the system to use double letters instead, in the sequence AA, AB... AZ, BA and so on.
If a comet splits, its segments are given the same provisional designation with a suffixed letter A, B, C, ..., Z, AA, AB, AC...
They receive a permanent number prefix after their second observed perihelion passage (see List of periodic comets).
The Roman numbering system arose with the very first discovery of natural satellites other than Earth's Moon: Galileo referred to the Galilean moons as I through IV (counting from Jupiter outward), in part to spite his rival Simon Marius, who had proposed the names now adopted.
[21] The idiosyncrasy found in the new-style provisional designations, no longer exists in this packed-notation system, as the second letter is now listed after the subscript number, or its equivalent 2-digit code.
The seventh character is usually 0, unless it is a component of a split comet, in which case it encodes in lowercase the letter of the fragment.
A packed form for permanent designations also exists (these are numbered minor planets, with or without a name).
The subsequent 4 characters encoded in Base62 (using 0–9, then A–Z, and a–z, in this specific order) are used to store the difference of the object's number minus 620,000.
[22] For natural satellites, permanent packed designations take the form of the planet letter, then three digits containing the converted Roman numeral (left-padded with zeroes), and finally an "S".