plural of psychological refractory period

plural of sidereal orbital period

plural of sidereal rotation period

plural of short-period comet

(astronomy) Any periodic comet with an orbital period of less than 200 years.

A time of warm climate in the North Atlantic region that may have been related to other climate events around the world during that time, and which lasted from about 950 to 1250.

plural of operational service period

plural of short period comet

(astronomy) The sidereal year of a planet. (I.e., in the definition for "sidereal year", replace "Earth" by the given planet.)

(astronomy) The sidereal day of a planet. (I.e., in the definition for "sidereal day", replace "Earth" by the given planet.)