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

The first → asteroid found to have an orbital → semi-major axis of less than one → astronomical unit. Discovered by the American woman astronomer Eleanor F. Helin (1932-2009) in 1982, it is the prototype of the → Aten asteroids.

Named after Aten, the Egyptian god of the solar disk.

A member of a class of → near-Earth asteroids with → perihelion distances between 0.983 and 1.0 → astronomical units. It is estimated that 6% of the total number of NEAs are Atens.

→ Aten; → asteroid.

A measure of the extent to which mass has been shifted from the polar regions of a (spinning) body toward its equator (Ellis et al., 2007, Planetary Ring Systems, Springer).

→ dynamic; → oblateness.

Present but not visible, apparent, or actualized; existing as potential (Dictionary.com). → latent heat.

From L. latentem (nominative latens), pr.p. of latere "to lie hidden."

Nahân "concealed, hid; clandestine;" Mid.Pers. nihân "secrecy, a secret place, a hiding place," nihânik "concealed;" Av. niδāti- "deposing, deposit."

The amount of → thermal energy that is absorbed or released by a unit amount of a substance in the process of a phase change under conditions of constant pressure and temperature.

→ latent; → heat.

The property possessed by a round body that is flattened at the poles.

Noun from → oblate.

(polar flattening) The ratio of the difference between equatorial and polar diameters to the equatorial diameter. A sphere has an oblateness of 0; an infinitely thin disk has an oblateness of 1 (Ellis et al., 2007, Planetary Ring Systems, Springer).

→ optical; → oblateness.

1) To utter a threat against; menace.
2) To be a menace or source of danger to (Dictionary.com).

From M.E. thretnen, from O.E. thrêatnian, → threat

Infinitive from harš, → threat.