Castor

Castor is a name used for several related subjects in biology and astronomy. The most familiar is the castor bean plant, Ricinus communis, a flowering shrub native to tropical regions of Africa and Asia. It produces large, lobed leaves and a spiny fruit containing seeds that carry the toxin ricin. The seeds are also the source of castor oil, a pale-yellow oil used in a wide range of products.

Castor oil is obtained by pressing castor seeds. In industrial and pharmaceutical contexts, the refining process removes or inactivates ricin, though handling raw seeds remains hazardous. Castor oil has diverse applications, including as a lubricant in machinery, an ingredient in cosmetics and soaps, and historically as a laxative in medicine. Its properties depend on the composition of the oil and the quality of processing.

In astronomy, Castor refers to a bright star in the constellation Gemini. It is part of a multiple star system, typically described as Castor A and Castor B, with additional distant companions. Castor lies opposite Pollux (Beta Geminorum) in the Gemini sky and has played a role in various cultural traditions that reference the twins from which the constellation takes its name.

The term castor therefore encompasses both a plant and its derived oil as well as a celestial object. In all uses, the word carries distinct meanings tied to botany, chemistry, and astronomy, with safety considerations primarily linked to handling the plant’s seeds.