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

A suffix used to form abstract action nouns corresponding to nouns with stems ending in → -scope.

From Gk. -skopia, → -scope + -ia.

-bini, from -bin, → -scope, + -i noun suffix.

A combining form used in the names of devices that stabilize or make constant what is specified by the initial element, e.g. → cryostat; → thermostat.

From Gk. -states, from sta- stem of histanai "to make stand," histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Pers. ist "to stand; to be standing, "from istâdan "to stand;" Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" PIE base *sta- "to stand."

Suffix -pâ, -pây present stem of pâyidan "to stand firm, to be constant, steady," from Mid.Pers. pattây-, pattutan "to last, endure, stay."

A suffix used to form abstract nouns from verbs to express action, state, or associated meanings.

From L. -tionem, accusative of noun suffix -tio (genitive -tionis).

-eš, from Mid.Pers. -išn.

A suffix forming personal agent nouns mainly from verbs, as in dictator, genitor, orator.

From L. -tor (examples), cf. Gk. -tor (examples), Av. -tar (astar "thrower," dātar- "giver," varštar- "producer"), Skt. -tr (datr- "giver," dartr- "breaker")

Agent suffix -gar, variant -gâr, from kar-, kardan "to do, to make" (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "makes;" cf. Skt. kr- "to do, to make;" krnoti "makes," karma "act, deed;" PIE base k^wer- "to do, to make"). Suffix -âr, as in parastâr, xaridâr, virâstâr. Agent suffix -andé, used with verbs.

A suffix used principally in the names of various devices and instruments (klystron; magnetron; cyclotron; synchrotron).

Perhaps a shortening of electron with accidental allusion to the Gk. instrumental suffix -tron, as in arotron "plough;" akin to O.E. -thor, suffix denoting an instrument; L. -trum; Skt. -tra.

A suffix denoting "turned toward" that specified by the initial element; → barotropic, → isotropic, → polytropic.

From Gk. -tropos "a turn, way, manner," from tropein "to turn," from PIE base *trep- "to turn" (cf. L. trepit "he turns").

Gard "turning, changing," from gardidan "to turn, to change," Mid.Pers. vartitan, Av. varət- "to turn, revolve," Skt. vartati, L. vertere, O.H.G. werden "to become;" PIE *werto, *wer-.

A suffix denoting the state of turning in a specified way.

From Gk. -tropia, from tropos "turn," trope "a turning."

Suffix form -gardi, from gardidan, gaštan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend").

A suffix meaning "small, little," as in → formula, → globule, → module, capsule, nodule.

From Fr. -ule, from L. diminutive suffix -ulus (feminine -ula, neuter -ulum).

Pers. diminutive suffix -ul, ulé, as in:
zangulé, zangul "small bell;"
kutulé, kutul "dwarf;"
golulé, gullé "small ball; bullet;"
maškulé (Torbat Heydariye-yi) "small water-skin;"
kandulé "a small jar for holding grain;"
jâšulé = small donkey (Kurd.);
Ahmadulé = little Ahmad (Kurd.);
rulé = "little child" (Kurd., Tâleši, Borujerdi, Malâyeri, and other Western dialects of Iran) probably from *ruduleh, cf. rud "child" (in zâd-o-rud) and Gilaki rey "boy;"
digul (Šuštari), digulé (Qomi) "small casserole, little pot;"
This suffix occurs also as -ulu, -âlé, and -élé as, e.g., in kuculu, cangul, panjul, bozqâlé, dâsqâlé, kâselé (Farâhâni) "small bowl," and barfelé (Farâhâni) "little snow."
Examples of use in this dictionary: disul → formula; karpul → corpuscle. See also -al → -al

A suffix denoting spatial or temporal direction, as specified by the initial element. Also -wards (Dictionary.com).

M.E., from O.E. -weard "toward," literally "turned toward;" PIE *wert- "to turn, wind," from *wer- "to turn, bend;" cf. Pers. gard-, gardidan "to turn, change," → revolve, → evolve.

-su, → direction.

The fourth largest → main belt asteroid and the only known → asteroid whose surface composition appears similar to that of the dwarf planet Ceres, suggesting a similar origin for these two objects. Hygiea suffered a giant impact more than 2 Gyr ago that is at the origin of one of the largest asteroid families. High angular resolution imaging observations of Hygiea with the VLT/SPHERE instrument (~20 mas at 600 nm) reveal a basin-free nearly spherical shape with semi-axes of 225 ± 5 km, 215 ± 5 km, and 212 ± 10 km and a volume equivalent radius of 217 ± 7 km. The shape and the best estimate of Hygiea's mass, (8.32 ± 0.80) × 10¹⁹ kg, yield a density of 1944 ± 250 kg m^-3. Such density is compatible, within errors, with Ceres' density (2161.6 ± 2.5 kg m^-3). These observations moreover, yield a new rotation period of ~ 13.8h for Hygiea, that is half of the currently accepted value. Numerical simulations of the family forming event show that Hygiea's spherical shape and family can be explained by a collision with a large projectile (Diameter ~ 75-150 km). By comparing Hygiea's sphericity with that of other solar system objects, it appears that Hygiea is nearly as spherical as Ceres, opening a possibility for this object to be reclassified as a dwarf planet (Vernazza et al., 2019, Nature Astronomy, 28 October).

in Greek mythology Hugieia / Hugeia was a daughter of the god of medicine, Asclepius, and Epione. She was the goddess, personification of health, cleanliness and sanitation. Her Roman name is Hygea/Hygia or Salus.

A → Near-Earth Object (NEO) which is a → B-type asteroid with a ~ 500 m diameter. Bennu completes an orbit around the Sun every 436.604 days (1.2 years) and every 6 years comes very close to Earth, within 0.002 → astronomical units. Bennu's composition (primitive and carbon-rich), size and proximity to Earth make it the ideal target for the → OSIRIS-REx project. Bennu is officially classified as a potentially dangerous asteroid. In fact, there's an 0.037 percent (or 1-in-2,700) chance that it will strike Earth in the last quarter of the 22nd century.

Named after the Egyptian mythological bird Bennu.

The largest → near-Earth asteroid, which is about 32 km in size. It belongs to the group of → Amor asteroids and has a → rotation period of about 10.31h. Ganymed was discovered by Walter Baade on October 23, 1924.

German rendering of → Ganymede. Note that Jupiter's moon Ganymede is named after the same, but uses a different spelling.

The largest → comet orbiting periodically around the → Sun. Its nucleus is about 26 km across and its orbital period 133 years. Comet Swift-Tuttle is the parent body of the → meteor shower called the → Perseids. The comet was discovered in July 1862, when it was apparently as bright as → Polaris in the night sky. The comet's reappearance was predictaed for 1992, when it was rediscovered by Japanese amateur astronomer Tsuruhiko Kiuchi. In 2126 it will be a bright naked-eye comet when it will come within about 23 million km of Earth, or about 60 times the distance from Earth to the Moon. Its nearest approach to Earth is expected in 3044, when the comet will come within 1.6 million kilometres of the Earth's surface.

Named after the American astronomers who independently discovered the comet in 1862, Lewis Swift (1820-1913) on July 16, and Horace Parnell Tuttle (1837-1923) on July 19.

The prototype of the → Amor asteroids discovered by the Belgian astronomer Eugène Joseph Delporte (1882-1955) on 12 March 1932. It is about 1 km across, has an → orbital period of 2.66 years, an → aphelion distance of 2.754 → astronomical units, and a → perihelion distance of 1.086 AU.

After the Roman god of love, better known as Cupid.

A → main belt asteroid comprised mostly of metallic iron and nickle (→ M-type asteroid). Psyche is a potato-shaped object with dimensions 279 × 232 × 189 km. Its average diameter, about 226 km, is about sixteenth the diameter of the → Moon. Psyche could be an exposed core of an early → planet that lost its rocky outer layers due to a number of violent collisions billions of years ago. The asteroid revolves around the Sun between the orbits of Mars and Jupiter at a distance ranging from 378 million to 497 million km from the Sun (2.5 to 3.3 Astronomical Units). Its revolution period is 4.99 Earth years and rotates about its axis every 4.196 h. This asteroid is the primary target of NASA's Psyche mission. Aimed to launch in August of 2022, the Psyche spacecraft would arrive at the asteroid in early 2026, following a Mars gravity assist in 2023. Over 21 months in orbit, the spacecraft will map and study Psyche's properties using a multi-spectral imager, a gamma-ray and neutron spectrometer, a magnetometer, and a radio instrument (for gravity measurement). The mission's goal is, among other things, to determine whether Psyche is indeed the core of a planet-sized object.

Psyche was discovered by Italian astronomer Annibale de Gasparis on March 17, 1852. He named the asteroid for Psyche, the Greek goddess of the soul who was born mortal and married Eros (Roman Cupid), the god of Love.

A → potentially hazardous asteroid of the → Apollo group. It is approximately 900 m across and displays the characteristics of → C-type asteroids. It was discovered by astronomers with the Lincoln Near-Earth Asteroid Research on May 10, 1999. Ryugu rotates every ~ 7.6 hours and revolves around the Sun in an elongated orbit with an → eccentricity of 0.1902 and a → semi-major axis of 1.1896 → astronomical units (au) in 1.30 years (474 days). Its → aphelion and → perihelion are at 1.4159 au and 0.9633 au, respectively. Ryugu was visited by the Japanese sample-return spacecraft → Hayabusa2 which arrived at the asteroid on June 27, 2018. It studied the asteroid with its several instruments and landers. It is expected to bring surface material to Earth in 2020.

Provisionally named 1999JU₃, Ryugu was officially adopted by the Minor Planet Center on September 28, 2015. The name relates to the Japanese folk tale of the fisherman Urashima Taro. He rescues a turtle from a group of children. The turtle takes him to an underwater palace known as "Ryugu" or "Dragon's Palace." He falls in love with a princess who begs him to stay, but after three days Urashima wishes to return home. As a parting gift, the princess gives the fisherman a box that she tells him never to open. Upon returning home, Urashima is stunned to find that 300 years have passed and everyone he knew has died. In confusion, he opens the box and is encased in a cloud of white fog. When the fog clears, he finds he is an old man, as the box contained his age.

A → near-Earth asteroid (NEA) that is the prototype of the → Apollo asteroids. It was discovered by the German astronomer Karl Reinmuth (1892-1979) in 1932, but was then lost until 1973. It has an estimated average diameter of 1.4 km, an → orbital period of 652 days, a → perihelion distance of 0.647 AU, and an → aphelion distance of 2.294 AU. It can come as close to Earth as 0.028 AU. Apollo has a small satellite of size less than one-tenth of the primary. Apollo was one of the two first asteroids in which the → YORP effect was detected.

Apollo or Apollon in Greek mythology the god of music and also of prophecy, medicine, archery, poetry, dance, intellectual inquiry and the carer of herds and flocks.

The first known → interstellar object coming from beyond → Solar System. Detected on October 19, 2017 by the → Pan-STARRS sky survey, it was initially classified as an interstellar → asteroid. 'Oumuamua has a strongly → hyperbolic orbit (→ eccentricity 1.191 ± 0.007), with a very high average velocity with respect to the Sun (v_∞ = 26.32 km s^-1), indicating that it likely originated from beyond our Solar System. Its → inclination with respect to the → ecliptic is 123°. 'Oumuamua would be approximately 160 m in diameter. This is the first known asteroid-like energetically unbound from the Sun. By comparison the → NASA Voyager 1 spacecraft travels about 17 km s^-1 through → interstellar medium. When first detected, 'Oumuamua was 0.2 → astronomical units (au) from the Earth (30 × 10⁶ km). Initially it was classified to be a → comet and was designated C/2017 U1. But further observations revealed no hint of → cometary activity. The object was therefore reclassified as an asteroid with designation A/2017 U1. According to orbit calculations, 'Oumuamua crossed under the → ecliptic plane just inside of Mercury's orbit and then went through → perihelion on September 9, 2017, at a distance of 0.25528 au (about 38 million km) from the Sun, speeding up to 87.71 km s^-1. Pulled by the Sun's gravity, the object made a U turn below the ecliptic, passing under Earth's orbit on October 14 at a distance of about 24 million km, that is about 60 times the distance to the Moon. It has now risen above the plane of the planets and is travelling at 44 km s^-1 with respect to the Sun. In 2197 it will be 1,000 au from the Sun. Recent → outgassing activity observed toward this object suggests that 'Oumuamua is most likely an interstellar comet and not an asteroid (Michelli et al., 2018, Nature 27 June).

The name 'Oumuamua approved by the IAU was submitted by the team at the Pan-STARRS telescope who discovered the object. It is a Hawaiian construct combining 'ou "to reach out" and mua "first" or "in advance of;" the second mua is for emphasis. 'Oumuamua is loosely translated as "scout" or "messenger." The 1I prefix indicates the interstellar nature of this first object.

The largest → asteroid and the second to be discovered, by Heinrich Olbers in 1802. Before the reclassification of → Ceres, Pallas was the second largest asteroid. Pallas is slightly irregular in shape with dimensions 570 x 525 x 482 km. It appears to have the same composition as → meteorites classed as low-grade → carbonaceous chondrites. Its → rotation period is 9 to 12 hours, and its → semi-major axis 2.773 → astronomical unints.

In Gk. mythology, Pallas was one of the Titans. The winged husband of Styx, he is the father of Nike and maybe Eos. Some legends claim that he is the father of Athena, possibly because of her nickname Pallas-Athena.

A new → dwarf planet found beyond Pluto's orbit, in the → Kuiper belt. It is roughly 700 km in size and has a highly elliptical orbit; it seems to come as close to the Sun as 34 → astronomical units (AU), and farther away than 120 AU. 2015 RR245 was discovered by an international team of astronomers using the Canada-France-Hawaii Telescope on Maunakea.

A provisional name.