comet, broom
彗 centers on a comet, with its sweeping tail visually evoking a broom. The broom sense is a natural extension of that sweeping, celestial shape.
彗 is thought to combine 丰 (possibly representing a hand holding a broom) with 彐 (a hand), together suggesting sweeping. The comet meaning likely arose from the broom-like tail of a comet.
The two 丰 shapes look like bristles of a broom, and the bottom 彐 is like a hand holding it. Imagine sweeping the sky with a broom and leaving a comet's tail.
For スイ, picture a comet sweeping across the sky, leaving a trail that looks like a long, thin 'sui' sound: sui -> スイ, like the whoosh of a broom.
comet
Halley's comet
Comet NEOWISE
Comet Hale-Bopp
periodic comet
great comet
to become famous overnight; to burst into fame
Comet Ikeya-Seki
Comet Hyakutake
short-period comet; periodic comet
long-period comet