An Etymological Dictionary of Astronomy and Astrophysics
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The angle between the light entering and exiting the prism when the light passing through the prism is parallel to the prism's base. Angle of minimum deviation (D) is used to measure the → index of refraction (n) of the prism glass, because: n = sin [(A + D)/2]/sin (A/2), where A is the → prism angle.

→ angle; → minimum; → deviation.

A 40-year period of unusually low → solar activity, from about 1790 to 1830. See also the → Maunder minimum.

Named after John Dalton (1766-1844), British meteorologist; → minimum.

The point x = c in an → interval where the value of the → function  f(y) is smaller than the value anywhere else in that interval. In other words, f(c) ≤ f(x) for all x in the interval.

→ local; → minimum.

A period from about 1645 to 1715 when the number of → sunspots was unusually low. This → solar activity minimum is attested also through the increased content of carbon 14 in tree rings in that period. The reason is that the cosmic rays which produce ¹⁴C reach the Earth in a greater number when there is weak solar activity (see also → radiocarbon dating). The Maunder minimum occurred during a period of cooling of the Earth, called the → Little Ice Age. The Maunder minimum is one of a number of periods of low solar activity, including the → Dalton minimum, the → Sporer minimum, the → Wolf minimum, and the → Oort minimum.

After the British astronomer Edward Walter Maunder (1851-1928) who, along with Gustav Spörer of Germany, first called attention to this phenomenon; → minimum.

The least value attained (or attainable) by a function; the opposite of maximum.

From L. minimum "smallest" (thing), neuter of minimus "smallest," superlative of → minor "smaller."

Kaminé, from kamin superlative of kam "little, few; deficient, wanting; scarce" (Mid.Pers. kam "little, small, few," O.Pers./Av. kamna- "small, few." Keh "small, little, slender" (related to kâstan, kâhidan "to decrease, lessen, diminish," from Mid.Pers. kâhitan, kâstan, kâhênitan "to decrease, diminish, lessen;" Av. kasu- "small, little;" Proto-Iranian *kas- "to be small, diminish, lessen") + -é nuance suffix.

Same as → angle of minimum deviation.

→ minimum; → deviation.

The minimum distance between the paths of two orbiting objects around a → primary. Such distance between an object and Earth is called Earth MOID.

→ minimum; → orbit; → intersection; → distance.

The amount of hydrogen necessary to form a star; more specifically the minimum mass to ignite → hydrogen fusion. → Hydrogen burning will start at a limit of about 0.08 Msun, or 75 → Jupiter masses. Below 0.08 Msun, the core never gets hot enough to trigger → hydrogen fusion. → Protostars less massive than this limit are known as → brown dwarfs or → planets if the mass is less than 13 Jupiter masses. Above 13 Jupiter masses, some minor nuclear reactions (→ deuterium burning) occur that do not provide much energy. The minimum mass for → star formation is a critical parameter with profound astrophysical, cosmological, and even anthropic consequences.

→ minimum; → stellar; → mass.

A 40-year period of unusually low → solar activity, from about 1010 to 1050. See also the → Maunder minimum.

→ Oort cloud; → minimum.

The month(s) during the 11 year → solar cycle when the number of → sunspots is lowest.

→ solar; → minimum.

A period of low → solar activity that lasted from about A.D. 1420 to 1570. It occurred before → sunspots had been studied, and was discovered by analysis of the proportion of carbon-14 in tree rings, which is strongly correlated with solar activity.

Named for the German astronomer Gustav Spörer (1822-1895); → minimum.

A period of low → solar activity that lasted from about A.D. 1420 to 1570. It occurred before → sunspots had been studied, and was discovered by analysis of the proportion of carbon-14 in tree rings, which is strongly correlated with solar activity.

Named for the German astronomer Gustav Spörer (1822-1895); → minimum.

Periods of time when the → relative sunspot number is low. These periods of time occur approximately every 11 years and represent the minimum in the → sunspot cycle.

→ sunspot; → minimum.

A 70-year period of unusually low → solar activity, from about 1280 to 1350. See also the → Maunder minimum.

→ Wolf number; → minimum.