noun
- astronomical instruments used to measure the angular diameter of celestial objects, especially the sun
Usage: astronomy; technical
Examples
- The observatory’s heliometers were used to study solar variations.
- Astronomers employed heliometers to measure the apparent size of distant stars.
- The precision of these heliometers allowed for accurate celestial measurements.
- Historical heliometers helped scientists understand stellar parallax.
- Modern telescopes have largely replaced traditional heliometers in astronomical research.