Translation guide
A helioscope is a specialized instrument for observing the sun safely. In Japanese, the most common term is a direct loanword, but there are also native compound words used in technical contexts.
The learner wants to refer to a device used for safely viewing the sun, especially in astronomy.
The most common and widely understood term, borrowed from English. Used in general and technical contexts.
He observed the sun with a helioscope.
Literally 'solar telescope'. A native compound often used in astronomical contexts. More descriptive than the loanword.
Means 'solar observation device'. A broader term that can include helioscopes but is less specific. Used in technical or scientific writing.
This solar telescope uses a special filter.
A new solar observation device was installed at the observatory.