Guwahati Planetarium is a useful change of pace from temples, riverfronts, and markets. Set near Dighalipukhuri, it has long served as Assam's main public astronomy centre, with dome shows and science programming aimed especially at students and families.
Check the current schedule before going, because shows and renovations can change the experience. When it is operating well, it is one of the better rainy-day stops in central Guwahati and a reminder that the city is a regional education hub as much as a gateway to the Brahmaputra valley.