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2d ago

Rubin Observatory Finds Fastest-Spinning Large Asteroid in First Commissioning Data

The peer-reviewed result validates Rubin's LSST Camera as a powerful engine for rapid small-body discovery.

This artist’s illustration depicts 2025 MN45 — the fastest-rotating asteroid with a diameter over 500 meters that scientists have ever found. The asteroid is shown surrounded by many other asteroids, depicting its location within the main asteroid belt. The Sun and Jupiter are shown in the distance. 2025 MN45 is 710 meters (0.44 miles) in diameter, and it completes a full rotation every 1.88 minutes. The discovery was made using data from NSF–DOE Vera C. Rubin Observatory, jointly funded by the U.S. National Science Foundation and the U.S. Department of Energy's Office of Science.
Image
This lightcurve shows how the asteroid’s brightness (x-axis) changes as it rotates (y-axis). Analyzing the curve allowed the team to calculate the asteroid's rotation speed, which sets a new record among asteroids of its size.

Overview

  • Asteroid 2025 MN45, about 710 meters wide, completes a rotation every 1.88 minutes, the fastest known spin for any asteroid larger than 500 meters.
  • Such a rapid spin exceeds the 2.2-hour breakup threshold for rubble piles, implying cohesive strength comparable to solid rock.
  • Early commissioning images revealed roughly 1,900 previously unknown asteroids and enabled reliable rotation measurements for 76, including 16 super-fast and three ultra-fast rotators.
  • All but one of the newly identified fast rotators are in the main asteroid belt, highlighting Rubin's ability to characterize faint, distant objects.
  • The study, published in The Astrophysical Journal Letters and presented at the AAS meeting, showcases the 3,200‑megapixel camera’s ~40‑second imaging cadence ahead of the decade-long LSST survey.