The rainbow, reportedly visible from 6:57 a.m. to 3:55 p.m. on Nov. 30, spanned the mountains near Taipei's Chinese Culture University for eight hours and 58 minutes.
Smithsonian Magazine, Tiny Fox Lab

On November 30, 2017, the world’s longest rainbow lasted for nearly 9 hours over the city of Taipei in Taiwan. – Tiny Fox Lab Facts

Preview photo credit: Smithsonian Magazine
Source: time.com/5049206/r…