What instrument is used to view the Sun during a solar eclipse?

The correct answer is the coronagraph. This instrument is specifically designed for observing the Sun's corona, which is the outer atmosphere of the Sun that becomes visible during a solar eclipse. A coronagraph creates an artificial eclipse by blocking out the direct light from the Sun's surface, allowing the fainter corona to be seen. This is essential for solar studies, as it enables scientists to observe the structure and dynamics of the corona without the overwhelming brightness of the Sun itself obstructing their view.

While telescopes can be used to view solar eclipses, they typically require solar filters to protect the observer's eyes and equipment from the Sun's brightness. A photoscope is another type of instrument designed for solar observation, but it is less commonly used than the coronagraph for scientific purposes in observing the corona specifically. A spectrometer analyzes the light spectrum but is not primarily used for visual observation during an eclipse. Thus, the coronagraph stands out as the most specialized tool for viewing the Sun during such an event.