An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A comet that has lost its ability to emit dust and gas and no longer displays the classic cometary features of a nebulous coma and a tail, or a destroyed comet. Comet Pigott The asteroid (944) Hidalgo is considered by some to be a defunct comet because of its unusual orbit. Another case is the asteroid Phaethon.

→ defunct; → comet.

A faint comet with the shortest known period (about 3.30 years). Its semimajor axis is 2.21 AU and aphelion 4.1 AU. it is the parent body of the Taurids meteor shower. The comet was first observed in 1786 by the French astronomer Pierre Méchain.

Named after the German astronomer Johann Franz Encke (1791-1865), who in 1819 computed its orbit and proved that sightings of apparently different comets in 1786, 1795, 1805, and 1818 were in fact appearances of the same comet. → comet.

The most famous comet orbiting the Sun once about every 75 years. The last time it appeared was in 1986, and it is predicted to return in 2061. Its earliest recorded sighting is traced back to 240 BC in China. In 1705 Edmond Halley used Newton's new theory of gravitation to determine the orbits of comets from their recorded positions in the sky as a function of time. He found that the bright comets of 1531, 1607, and 1682 had almost the same orbits. He concluded that these appearances must belong to a single recurring comet, and predicted its return for 1758. Halley's comet is the first known → periodic comet, hence its → designation 1P/Halley.

Named after the English astronomer Edmond Halley (1656-1742), who first computed its orbit and predicted its return in 1758; → comet.

A comet with orbital period of more than 200 years. → short-period comet; → periodic comet.

→ long; → period; → comet.

A final product or end result; consequence; issue (Dictionary.com).

→ out; → come.

Borunšod "outcome," from borun, → out, + šod, šodan "to go, to pass, to change," → become.

A comet with a period of less than 200 years. Also called short-period comet.

→ periodic; → comet.

A comet with a period less than 200 years. Same as → periodic comet.

→ short; → period; → comet.

An instrument used to measure the → viscosity of a liquid. Same as viscosimeter.

→ viscosity; → -meter.