[ sid-er-uh-stat ]
/ ˈsɪd ər əˌstæt /


a telescopic device for reflecting the light of a star in a constant direction, the chief component of which is a plane mirror turned by a clock mechanism to correct for the rotation of the earth.

Origin of siderostat

First recorded in 1875–80; sidero-2 + -stat


sid·er·o·stat·ic, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for siderostat

  • The movable portion of the roof of the building had been slid back, and the mirror of the siderostat stood bared to the sky.

  • The siderostat, twenty-seven feet high, and as many in length, weighed forty-five tons.

  • The telescope was housed at the Exhibition in a long gallery pointing due north and south, the siderostat at the north end.

British Dictionary definitions for siderostat

/ (ˈsaɪdərəʊˌstæt) /


an astronomical instrument consisting essentially of a plane mirror driven about two axes so that light from a celestial body, esp the sun, is reflected along a constant direction for a long period of timeSee also heliostat Compare coelostat

Derived forms of siderostat

siderostatic, adjective

Word Origin for siderostat

C19: from sidero-, from Latin sidus a star + -stat, on the model of heliostat
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012