he·​lio·​stat ˈhē-lē-ə-ˌstat How to pronounce heliostat (audio)
: an instrument consisting of a mirror mounted on an axis moved by clockwork by which a sunbeam is steadily reflected in one direction

Examples of heliostat in a Sentence

Recent Examples on the Web On the roof of the Swiss Federal Institute of Technology, this heliostat array focuses sunlight on a reactor that can turn carbon dioxide from the air into fuel. Frank Swain, Discover Magazine, 13 June 2020 The furnace’s heliostat, a 40-foot-wide panel of 36 mirrors (not visible here), tracks the sun across the sky, reflecting light into the attenuator (1), a grate that can be opened or closed like a window blind. Danielle Egan, Discover Magazine, 16 Dec. 2010 Placing three heliostats, spaced every 120 degrees along a crater rim would ensure steady illumination to the mine, and two more would beam light at the vapor capture tent and fuel processing plant, according to Sowers. Joe Pappalardo, Popular Mechanics, 27 Apr. 2020 But those peak around 1,000 degrees, because each heliostat has to be individually calibrated and can fall out of alignment over time. Laura Mallonee, Wired, 21 Jan. 2020 The researchers found that for a solar plant with a central tower, the efficiency of the heliostats closest to the tower was higher. Shweta Narayan, Smithsonian, 31 Aug. 2019 The plant, operated by Torresol Energy, consists of 2,650 heliostats — mirrors that turn to track the motion of the sun, fanning out around, and reflecting sunlight toward, a 150-meter (490-foot)-high tower. Shweta Narayan, Smithsonian, 31 Aug. 2019 Molten Salt Thermal Storage Molten salt can retain heat for a long time, so it's generally found in solar thermal plants, where dozens or hundreds of heliostats (large mirrors) use the heat from sunlight to create energy. Megan Geuss, Ars Technica, 28 Oct. 2017 The facility consists of an array of heliostats—or panels that reflect sunlight onto a thermal tower—and a molten salt tank. Megan Geuss, Ars Technica, 13 Oct. 2017 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'heliostat.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


New Latin heliostata, from heli- entry 1 + Greek -statēs -stat

First Known Use

1747, in the meaning defined above

Time Traveler
The first known use of heliostat was in 1747

Dictionary Entries Near heliostat

Cite this Entry

“Heliostat.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heliostat. Accessed 4 Dec. 2023.

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