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

A joint endeavor of → NASA, → ESA, and the Italian space agency that sent a spacecraft to study the planet → Saturn and its system, including → Saturn's rings and its natural satellites. The spacecraft was 6.70 m × 4 m × 4 m and weighed about 6 tons. Cassini drew its electric power from the heat generated by the decay of 33 kg of → plutonium-238. The spacecraft carried 12 sophisticated observation and measuring instruments. Cassini-Huygens was launched on 15 October 1997. It used several → gravity assist manoeuvres to boost itself toward Saturn. It flew past Venus two times (April 1998 and June 1999), made → flybys of Earth (August 1999), and f Jupiter (December 2000). After 6 years and 8 months, covering about 8 billion km it entered Saturn orbit on July 1, 2004. It stayed there for 13 years and made detailed observations of the planet, its rings, and its moons. A scientific probe called Huygens was released on December 25, 2004 from the main spacecraft to parachute through the atmosphere to the surface of Saturn's largest and most interesting moon, → Titan. The data that Huygens transmitted during its final descent and for 72 minutes from the surface included 350 pictures that showed a shoreline with erosion features and a river delta. Cassini continued to orbit Saturn and complete many flybys of Saturn's moons. A particularly exciting discovery during its mission was that of → geysers of water ice and organic molecules at the south pole of → Enceladus, which erupt from an underground global ocean that could be a possible environment for life. Cassini's radar mapped much of Titan's surface and found large lakes of liquid → methane. Cassini also discovered six new moons and two new rings of Saturn. The mission was ended on September 15, 2017 when the spacecraft was crashed into Saturn's body and destroyed. This was the best way to avoid contaminating Saturn's moons with possible Earth microbes, because the moons may have the potential to support life.

Named after two famous scientists. The Saturn orbiter is named after the Italian/french astronomer Jean-Domenique Cassini, who discovered the Saturnian satellites → Iapetus in 1671, → Rhea in 1672, and both → Tethys and → Dione in 1684. In 1675 he discovered what is known today as the → Cassini division, the narrow gap separating Saturn's rings into two parts. The Titan probe was named Huygens in honor of the Dutch scientist, Christiaan Huygens, who discovered Titan in 1655.

PIE prefix *ni- "down, below."

E. nether is from this PIE root; M.E. nethere, O.E. neothera, nithera "down, downward, below, beneath" (cf. O.S. nithar, O.N. niðr, O.Fris. nither, Du. neder, Ger. nieder); akin to Pers. ne-, ni-, as below.

Mod.Pers. ne-, ni- "down, below" (as in negâh "look, watch," nešastan "to sit down," nehoftan "to conceal," nehâdan "to place, put," nemudan "to display," nefrin "curse," etc.); Mid.Pers. ni-, O.Pers. preposition and verbal prefix ni- "down;" Av. nī- "down, in, into;" cf. Skt. ni- "down," nitaram "downward;" Gk. neiothen "from below" (from ne-[io]- "below" + -then "from, since;" other usage examples of -then: po-then "from where," paidio-then "since childhood," panta-ho-then "from everywhere."); E. nether, as above.

All, universally.

L. omni-, combining form of omnis "all, every," of unknown origin.

Visp-, from Mid.Pers. visp- "all;" O.Pers. visa-, vispa- "all;" Av. vīspa- "all, every, entire, universal" (vīspô.ayāra- "lasting all the days," vīspô.vīδvah- "knowing everything, omniscient"); cf. Skt. vīśva- "all, every; whole, universal."

Variant of → plano-, as in → planisphere.

→ plane.

A method for finding the value of a → polynomial given by a real number and deriving its → roots. It consists essentially of factoring the polynomial in a nested form. Also known as → nested multiplication.

Named after Paolo Ruffini (1765-1822) and William Horner (1786-1837), who independently elaborated the method; → method.

A prefix with the meaning of "one" occurring in loanwords from L., such as → uniform, → uniaxial, → universe, etc.

From uni- a combining form meaning "one," from L. uni-, from unus, → one;

Yek-, from yek, → one.