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

Of great weight; of great amount, quantity.

M.E. hevi; O.E. hefig, from P.Gmc. *khabigas (cf. O.N. hebig).

Sangin "heavy, weighty; stony, like stone, hard," from sang "stone, rock" (Mid.Pers. sang; O.Pers. aθanga-; Av. asenga- "stone" (related to Mod.Pers. âsmân "sky" → heaven); PIE *aken-) + -in adj. suffix.

In astrophysics, any → chemical element heavier than → helium. Such elements are also inappropriately referred to as "→ metals."

→ heavy; → element.

→ deuterium.

→ heavy; → hydrogen.

Water in which the hydrogen is replaced by → deuterium. Deuterium Oxide (D₂O).

→ heavy; → water.

A → lunisolar calendar used by Jews for religious purposes. The year consists of 12 months alternating between 29 and 30 days, making a year of 354 days. In order to conform to the → solar year, a → leap month is included every third year. A month begins the day the new moon is first seen. The years are counted from the time of "creation," believed by Jewish theologians to have occurred in the year 3761 B.C. Also called → Jewish calendar.

Hebrew, from O.E., from O.Fr. Ebreu, from L. Hebraeus, from Gk. Hebraios, from Aramaic 'ebhrai, corresponding to Heb. 'ibhri "an Israelite," literally "one from the other side," in reference to the River Euphrates, or perhaps simply denoting "immigrant;" from 'ebher "region on the other or opposite side;" → calendar.

Gâhšomâr, → calendar; yahud→ Jewish calendar.

A prefix meaning hundred (10²) used in the formation of compound words.

From Fr., from Gk. hekaton "hundred."

Hekto-, loanword from Fr., as above.

Distance upward from a given level to a fixed point.

M.E., from O.E. hiehthu; → high + -th a suffix forming nouns of action (e.g., birth) or abstract nouns denoting quality or condition (depth; length; warmth).

Bolandi, bolandâ "height," noun forms from boland "high," variants bâlâ "up, above, high, elevated, height," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Lori dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. & E. force); O.E. burg, burh "castle, fortified place," from P.Gmc. *burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city," E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg); PIE base *bhergh- "high."
Farâzâ, noun of farâz "above, up, upon, on the top, aloft," from Mid.Pers. farâz, farâc "forward, prominent, distinguished;" Av. frānk- (adj.) "turned toward the front," fraca (adv.) "forward, forth," fraš (adv.) "forward, forth; before;" Proto-Iranian *frānk-.

A diffuse bright region surrounding the shadow that an observer's head casts on an irregular surface. It can be best observed on dewy reeds or grass. This phenomenon is reminiscent of the → glory, but without its color and regular structure.

Heiligenschein, Ger., literally "saint's shining light," from heiligen, from heilig "holy, sacred" (P.Gmc. *khailagas; M.H.G. heilec; O.H.G. heilag; Goth. hailag; O.N. heilagr; O.E. halig; E. holy) + Schein "glow, shine" (M.H.G. schinen, O.H.G. skinan, P.Gmc. *skinanan; E. shine; cf. Mod.Pers. sâyé "shadow;" Mid.Pers. sâyak "shadow;" Av. a-saya- "throwing no shadow;" Skt. chāya- "shadow;" Gk. skia "shade;" Rus. sijat' "to shine;" PIE base *skai- "bright").

Sepant foruq, from sepant "holy" (Mid.Pers. spand "holy," Spandarmat "Holy Thought; 5-th day of the month; 12-th month of the year;" from Av. spənta- "holy; beneficent," spəntô.mainyav- "coming from or belonging to the holy spirit," spəntô.təma- "holiest") + foruq "light, brightness" (related to rôšan "light; bright, luminous;" ruz "day," afruxtan "to light, kindle;" Mid.Pers. payrog "light, brightness," rošn light; bright," rôc "day;" O.Pers. raucah-; Av. raocana- "bright, shining, radiant," raocah- "light, luminous; daylight;" cf. Skt. rocaná- "bright, shining, roka- "brightness, light;" Gk. leukos "white, clear;" L. lux "light" (also lumen, luna; E. light, Ger. Licht, and Fr. lumière; PIE base *leuk- "light, brightness").

A person who inherits or has a right of inheritance in the property of another following the latter's death (Dictionary.com).

→ heritage.

The uncertainty in the measurement of the position and momentum of an elementary particle. The more precisely one quantity is known, the less certain the precision of the other. A similarly linked pair of quantities is the time and energy content in a volume of space.

Named after Werner Heisenberg (1901-1976), the German physicist who in 1927 derived the uncertainty principle. In 1932 he was awarded the Nobel Prize in Physics; uncertainty, from → un- "not" + → certainty; → principle.

Of or near the → Sun, especially rising and setting with the Sun. → heliacal rising, → heliacal setting.

Heliacal "pertaining to the sun," from Gk. heliakos "of the sun," from helios, → sun; cognate with Pers. hur, as below.

Hurâné "sunlike," since the star rises in the morning like the Sun, from hur "sun", variant xor; Mid.Pers. xvar "sun;" Av. hû-, hvar- "sun;" Skt. surya-; L. sol; O.H.G. sunna; Ger. Sonne; E. sun; PIE *sawel- "sun" + -âné similarity suffix.

The first appearance of a star following a period of invisibility due to its conjunction with the Sun. → heliacal rising of Sirius.

→ heliacal; → rising.

The first rising of → Sirius at dawn shortly before → sunrise. The heliacal rising of Sirius played a significant role in ancient Egypt by heralding the annual flooding of the Nile. The event took place some 70 days after the star had been seen for the last time in the western horizon at sunset. The heliacal rising of Sirius and its association with the rebirth of the Nile was so important that it marked the start of the Egyptian calendar year. At the time, the heliacal rising occurred in early July, as seen from the ancient capital of Memphis. But due to the → precession of the equinoxes the star now reappears in early August in Egypt. The date depends on the latitude (assuming transparent skies), being later for higher latitudes. For latitude 48° it occurs on about August 19.

→ heliacal; → rising; → Sirius.

The last visible setting of a star below the western horizon just after sunset entering into a conjunction with the Sun.

→ heliacal; → setting.

1) In particle physics, the projection of the spin of an elementary particle on the direction of momentum.
2) In fluid mechanics, → kinetic helicity.
3) In magnetohydrodynamics, → magnetic helicity.

From → helix + → -ity.

A combining form of Gk. helios "sun."

Helio-, combining form of from Gk. helios "sun;" cognate with Persian hur "sun", variant xor and xoršid (Av. hvarə-xšaēta- "shining sun"); Mid.Pers. xvar "sun;" Av. hû-, hvar- "sun;" Skt. surya-; L. sol; O.H.G. sunna; Ger. Sonne; E. sun; PIE *sawel- "sun."

Having or representing the Sun as a center. → heliocentric cosmology, → heliocentric gravitational constant, → heliocentric Julian Day, → heliocentric parallax, → heliocentric system.

→ helio- + → center + → -ic.

A model of the Universe in which the Sun was centrally located.

→ heliocentric; → cosmology.

A parameter representing the product of the → gravitational constant by the → solar mass. It is 13.27 x 10¹⁹ m³ s^-2.

→ heliocentric; → gravitational; → constant.

The → Julian Date referenced to the center of the → Sun. Since the Earth revolves around the Sun, and since light travels at a finite speed, observations of a given object taken at different positions in the Earth's orbit are not equivalent, and so a correction for Earth's orbit around the Sun is required. Left uncorrected, the time of an observational event measured by Earth clocks will vary by 16.6 minute over the course of a year. If not properly accounted for, this can lead to a spurious signal in a → periodogram.

→ heliocentric; → Julian Date.