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

1) A small hole such as a space especially in a rock, soil, etc. → porous dust grain, → porosity.
2) A minute orifice in an animal or plant, as in the skin or a leaf.
3) Sun: A small → sunspot that does not have a → penumbra. Pores are up to about 2,500 km across and are lighter than a sunspot's → umbra. They appear and disappear at the surface of the Sun where sunspots are rarely formed, e.g. at low latitudes. Their lifetimes can be as short as 1/2 hour and as long as several days.

From L. porus "a pore," from Gk. poros "a pore," literally "passage, way," from PIE root *per- "to lead, pass over."

Lik, from Gilaki lik "hole," variants luk, luke, liuk, luxa, Tabari luk, li, Sangesari, Semnâni lu, Aftari lo.

A reproductive body in flowerless plants corresponding to the seeds of flowering ones.

From Modern L. spora, from Gk. spora "a seed, a sowing, seed-time," related to speirein "to sow, scatter."

Hâg, variant of xâg, → egg.

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.

The empirical law that predicts the variation of → sunspot latitudes during a → solar cycle. At the start of a sunspot cycle, sunspots tend to appear around 30° to 45° latitude on the Sun's surface. As the cycle progresses, they appear at lower and lower latitudes, until 5° to 10°, at the end of the cycle. This tendency is revealed on a → butterfly diagram. Although named after Gustav Spörer, the "law" was first discovered by Richard Carrington.

→ Sporer minimum; → law.

The empirical law that predicts the variation of → sunspot latitudes during a → solar cycle. At the start of a sunspot cycle, sunspots tend to appear around 30° to 45° latitude on the Sun's surface. As the cycle progresses, they appear at lower and lower latitudes, until 5° to 10°, at the end of the cycle. This tendency is revealed on a → butterfly diagram. Although named after Gustav Spörer, the "law" was first discovered by Richard Carrington.

→ Sporer minimum; → law.