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

A compact format for writing very large or very small numbers. Numbers are made up of three parts: the coefficient, the base and the exponent. For example 3.58 x 10⁴ is the scientific notation for 35,800.

→ scientific; → notation.

The quality of the practices and theories that aim at establishing reproducible regularities in phenomena by using experimental method and providing a clearly formulated description.

→ scientific + → -ity.

A pioneering work in → spectral classification conducted in the 1860s. Secchi divided stars into four main groups based on the visual observation of spectra. Class I: The white and bluish stars with a continuous spectrum crossed by hydrogen bands, the metallic bands being absent or weak. Examples, → Sirius, → Vega. Class II: Yellow stars, with spectra in which the hydrogen bands were less prominent and the metallic lines more strong. Examples, Sun, → Capella. Class III: Red or orange stars, showing bands or flutings. Examples, → Antares, → Betelgeuse. Class IV: Red stars, showing bands similar to Class III, but with the sharp edge of the flutings toward the other end of the spectrum. Secchi's scheme was superseded by the photographic → Harvard classification system.

Pietro Angelo Secchi (1818-1878), Italian astronomer and Jesuit priest; → classification.

A change in place or position, in particular a change in wavelength, causing a movement of a spectral band or line. → redshift; → blueshift.

Shift, M.E., from O.E. sciftan "to divide, arrange"; akin to O.N. skipa "to arrange, assign."

Kib "shift" from kibidan "to shift, displace, turn on one side," kibidé "displaced, turned on one side."

1) The state or quality of being significant; → meaning; importance.
2) Statistics: An estimated measure of the degree to which a result is not merely a matter of chance. See also → significance level, → significance testing.

From L. significantia "meaning, force, energy," from significans, present participle of significare, → signify.

Nešânâri, noun from nešânâr, → significant.

The level of → Type I error which one is willing to risk in a → test of significance. Also called level of significance.

→ significance; → level.

Statistics: A procedure that is used to decide whether to accept or reject the → null hypothesis or to determine whether observed samples differ significantly from expected results. Also called → test of significance and → rule of decision.

→ significance; → test.

1) Having a special or suggestive → meaning.
2) Statistics: Of or pertaining to a result that is not plausible to occur by chance.

From L. significant-, stem of significans, from significare, "to → signify."

Nešânâr, from nešân, → sign, + âr short form of âvar present stem of âvardan "to bring, adduce, cause, produce."

The number of digits used to express a measured or calculated quantity. Rules for deciding the number of significant digits:
The leftmost digit which is not a zero is the most significant digit.
If the number does not have a decimal point, the rightmost digit which is not a zero is the least significant digit.
If the number does have a decimal point, the rightmost significant digit is the least significant digit, even if it's a zero.
Every digit between the least and most significant digits should be counted as a significant digit.

→ significant; → digit.

1) Something that is signified, → meaning, sense.
2) The act of signifying. → significance, → significant, → level of significance.

Verbal noun of → signify.

To make known; to be a sign of; to → mean. → significance, → significant, → signification.

M.E. signifien, from O.Fr. signifier, from L. significare "to make a sign, indicate, mention, denote."

Nešânâridan, from nešânâr, → significant, + -dan suffix of infinitives.

The act of simplifying, or the fact of being simplified.

Verbal noun of → simplify.

1) To make less complex or complicated.
2) Math.: Reduce an → expression by → algebraic manipulations.

→ simple + epenthesis -i- + → -fy.

An asteroid taxonomy built on the → Tholen classification but based on the presence or absence of → absorption features in the visible part of the spectrum. In many cases the two classifications are the same, but the Tholen C and S classes are subdivided in the SMASS classification.

SMASS stands for the Small Main-belt Asteroid Spectroscopic Survey, → small; → main belt; → asteroid; → spectroscopic; → survey; → classification.

A mound or bank of snow deposited as sloping surfaces and peaks, often behind obstacles and irregularities, due to eddies in the wind field.

→ snow; → drift.

Barf-rând "snowdrift, drfited snow" from barf, → snow, + rând "driving, drfit; drifted," from rândan "to push, drive, cause to go," causative of raftan "to go, walk, proceed" (present tense stem row-, Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack"); barf-e bâd âvard "snow brought by wind," from barf + bâd→ wind + âvard, short for âvardé "brought," p.p. of âvardan "to bring; to cause, produce" (Mid.Pers. âwurtan, âvaritan; Av. ābar- "to bring; to possess," from prefix ā- + Av./O.Pers. bar- "to bear, carry," bareθre "to bear (infinitive)," bareθri "a female that bears (children), a mother;" Mod.Pers. bordan "to carry;" Skt. bharati "he carries;" Gk. pherein; L. fero "to carry").

1) To become or make solid, hard, or firm.

→ solid; → -fy.

1) To become or make solid, hard, or firm.

→ solid; → -fy.

1) Clearly defined or identified; precise; particular.
2) Belonging or relating uniquely to a particular subject; not general.
3) Biology: Relating to species or a species.
4) Physics: Of or denoting a physical quantity expressed in terms of a unit mass, volume, or other measure, in order to give a value independent of the properties or scale of the particular system studied. → specific angular momentum; → specific charge; → specific density; → specific gravity; → specific heat; → specific humidity; → specific intensity; → specific volume.

From Fr. spécifique and directly from L.L. specificus "constituting a kind or sort," from L. species "kind, sort," → species.

Âbizé, from Mid.Pers. apēcak "pure, sacred" (older form of vižé, → special), from *apa-vēcak "set apart," from prefix apa- + vēcak, from vēxtan (Mod.Pers. bixtan) "to detach, separate, sift, remove," Av. vaēk- "to select, sort out, sift," pr. vaēca-, Skt. vic-, vinakti "to sift, winnow, separate; to inquire."

→ Angular momentum per unit mass.

→ specific; → angular; → momentum.

The electric charge to mass ratio of an elementary particle.

→ specific; → charge.