He was a pioneer in astronomical spectroscopy , and was one of the first scientists to state authoritatively that the Sun is a star .
He was Director of the Observatory at the Pontifical Gregorian University ( then called the Roman College ) for 28 years .
Director was a pioneer in astronomical spectroscopy , and was one of the first scientists to state authoritatively that the Sun is a star .
He was Director of the Observatory at the Pontifical Gregorian University ( then called the Roman College ) for 28 years .