New Delhi: Astronomers have discovered the fastest-spinning asteroid ever observed with a diameter exceeding 500 metres using the Vera C Rubin observatory.
The object is designated as 2025 MN45, and measures about 710 metres across, roughly the length of eight American football fields, and completes a full rotation every 1.88 minutes. The discovery is detailed in the first peer-reviewed paper based on data by the observatory’s new Legacy Survey of Space and Time (LSST) camera and has been published in The Astrophysical Journal Letters. The research is based on observations collected over a period of around ten hours across seven nights in April and May 2025, during the early commissioning phase of the telescope.
The Vera C Rubin Observatory is located in Cerro Pachon in Chile and is equipped with the largest digital camera in the world that is purpose-built for the Legacy Survey of Space and Time (LSST), a decade-long project to repeatedly image the Southern Hemisphere sky. Although full operations are set to begin soon, the pre-survey ‘First Look’ data has already yielded science results, with the discovery of about 1,900 previously unknown asteroids. Among these, the team detected 19 super and ultra-fast rotating asteroids, with 76 having reliable rotation periods. The nineteen exceed typical spin limits, with 16 super-fast rotators, taking roughly between 13 minutes and 2.2 hours for a rotation, with three ultra-fast ones that complete rotations in under five minutes. All but one of these reside in the main asteroid belt between Mars and Jupiter, where the discovery of such faint, rapidly moving objects is challenging.
What the rotations reveal
Asteroid rotation rates provide insights into their formation, internal structure and history. Most asteroids are rubble piles, loose aggregates held together by gravity. The asteroids with faster spins risk fragmentation unless the body possesses significant cohesive strength. 2025 MN45 has to be made up entirely of solid rock to maintain the extreme rotation. Researchers suggest that it may be a fragment from an ancient collision involving a larger, differentiated parent body, or in other words, a long-long world. Scientists anticipate the discovery of many more such objects as the survey accumulates data.
