An Etymological Dictionary of Astronomy and Astrophysics
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An extensive constellation, one of the 48 constellations known to Greeks, representing the ship of Argonauts. It was divided in 18th century into the constellations → Carina, → Puppis, and → Vela.

The ship in which Jason sailed in search of the Golden Fleece.

Kašti "ship," from Mid.Pers. kaštik.

1) The act, fact, or occupation of writing.
2) Source or origin, as of a book or idea.

→ author.

O.E. hype "hip," akin to Du. heup, O.H.G. huf, Ger. Hüfte, Swed. höft, Goth. hups "hip," of uncertain origin.

Šanj (Dehxodâ) "hip, buttock, thigh, haunch," of unknown origin.

A → European Space Agency satellite, which was launched in August 1989 and operated until March 1993. It was the first space mission devoted to → astrometry with an unprecedented degree of accuracy. The telescope on Hipparcos had a main mirror of diameter 29 cm. Calculations from observations by the main instrument generated the Hipparcos Catalogue of 118,218 stars charted with the highest precision (published in 1997) containing positions, distances, → parallaxes, and → proper motions. An auxiliary star mapper pinpointed many more stars with lesser but still unprecedented accuracy, in the Tycho Catalogue of 1,058,332 stars. The Tycho 2 Catalogue, completed in 2000, brings the total to 2,539,913 stars, and includes 99% of all stars down to magnitude 11. → Gaia.

Hipparcos, acronym for → High  → Precision  → Parallax  → Collecting → Satellite, chosen for its similarity to the name of the Greek astronomer Hipparchus of Nicaea (c. 190-125 BC), one of the most influential astronomers of antiquity, who compiled an extensive star catalogue in which he gave the positions of over 1,000 stars and also classified them according to their magnitude (on a scale of 1 to 6, brightest to faintest). Ptolemy later incorporated this information into his → Almagest. In addition, he discovered the → precession of the equinoxes.

The smallest known moon orbiting the planet → Neptune, discovered in 2013. Hippocamp has an estimated diameter of only about 34 km and orbits close to → Proteus, the outer and the second largest of Neptune's moons. The orbital → semi-major axes of the two moons differ by only 10%. Hippocamp is probably an ancient fragment of Proteus. Billions of years ago a comet collision would have chipped off a chunk of Proteus. Images from the Voyager 2 space probe from 1989 show a large → impact crater on Proteus, whose size compares with Hippocamp's (Showalter et al., 2019, Nature 566, 350).

Formerly known as S/2004 N 1, Hippocamp is named after the sea creatures in Greek and Roman mythology. The mythological Hippocampus possesses the upper body of a horse and the lower body of a fish. The Roman god Neptune would drive a sea-chariot pulled by Hippocampi.

A curve described by the → polar equation  r² = 4b (a - b sin²θ), where a and b are positive constants. For appropriate values of a and b, the curve looks like the infinity symbol, ∞. See also → spheres of Eudoxus.

Hippopede, literally "a horse's foot," denoting a "horse fetter (hobble)," from Gk. hippos, → horse, + -pede variant of -ped, combining form of pos,→ foot.

The state of being a member.

From → member + -ship a native E. suffix of nouns denoting condition, character, office, skill, etc., from M.E., O.E. -scipe; akin to shape.

hamvandi, from hamvand, → member, + -i condition, character suffix.

One of several functions used in the → fuzzification and → defuzzification steps of a → fuzzy logic system to map the → nonfuzzy input values to → fuzzy linguistic terms and vice versa. A membership function is used to quantify a linguistic term.

→ membership; → function.

A concept whereby properties of objects vary according to the energy with which they are probed. An atomic system in its → ground state tends to remain as it is if little energy is fed in, betraying no evidence of its internal structure. Only when it is excited into a higher state do complexities emerge. This is the essence of quantum censorship. Thus, below an energy threshold, atoms appear to be impenetrable. Above it, their components can be exposed (F. Wilczek, 2013, Nature 498, 31).

→ quantum; censorship, from censor, from M.Fr. censor and directly from L. censor "a Romain magistrate who kept the register or census of the citizens, and supervised morals," from censere "to appraise, value, judge," from PIE root *kens- "to speak solemnly, announce;" cf. Av. səngh- (sanh-) "to declare, explain;" Pers. soxan "word, speech;" Skt. śams- "to praise, recite."