Part 6/15:
Reflective telescopes offered advantages: they avoided chromatic aberration common in lens-based telescopes and could be built with larger apertures more practically and affordably. The advent of wide mirrors permitted astronomers to gather more light—crucial for observing distant stars and galaxies. They paved the way for larger telescopes in observatories worldwide, such as the Leviathan of Parsonstown, a massive 72-inch mirror telescope built in Ireland in 1845 that first revealed the spiral arm structures of galaxies.