Ultra‑fast large asteroids imply monoliths

Rubin Observatory found asteroid 2025 MN45 (~0.5 mile) spinning every 1.88 minutes — far faster than expected for a >500 m 'rubble‑pile' body. Such extreme rotation in a large object implies a cohesive, monolithic fragment (likely from a differentiated parent) and forces a rethink of collisional and thermal processing in the early solar system. — This changes scientific narratives about asteroid formation and internal structure, affects impact‑risk assessments for large bodies, and showcases Rubin Observatory’s rapid discovery and characterization power—an infrastructure story with policy and funding implications.