An international team of astronomers has detected a large asteroid with the fastest rotation ever measuredThis discovery is generating considerable discussion within the scientific community. The object, located thanks to the Vera C. Rubin Observatory, has become a veritable natural laboratory for studying the resistance of the materials that make up these rocky bodies.
This discovery represents a turning point in the study of asteroids and the early evolution of the Solar System. Although the discovery was made from an observatory located in Chile, its results are of enormous interest to the European and Spanish astronomical community, which is heavily involved in data analysis and projects related to planetary defense.
An observatory designed to revolutionize the study of the sky
The Vera C. Rubin Observatory, operated in the southern hemisphere, has been designed to to systematically monitor the night sky with unprecedented frequency and accuracyIts partial launch in 2025 has already been enough to demonstrate what it is capable of: during the first campaigns it has managed to catalog thousands of asteroids, many of them completely unknown until now.
In this early phase, the scientific team has identified thousands of moving objectsincluding more than 1.900 asteroids never before seen in previous observations. This avalanche of new data is key to better understanding the population of minor bodies that move between Mars and Jupiter. even between Mercury and Venus, near Earth and in other regions of the Solar System.
Much of this success is due to the observatory's main camera, associated with the Legacy Space and Time Study (LSST) project. This camera, considered the largest ever installed on an optical telescopeIt allows you to obtain images of the sky with a level of detail and speed that is hard to match.
Thanks to this technology, Rubin is able to take a new picture of the sky approximately every 40 secondsThis high cadence makes it easier to detect fast-moving bodies, accurately measure their brightness, and deduce their rotation period in very short time intervals, something essential for locating extremely spin asteroids like the protagonist of this story.
Project managers have emphasized that Rubin It will uncover phenomena that had not even been considered as possible search objectives.The first observations are already confirming this, positioning the observatory as a reference tool also for European institutions that collaborate in the scientific analysis of its data.
Asteroid 2025 MN45: a giant spinning at full speed
Among all the objects discovered in the initial campaigns, one very peculiar asteroid stands out, designated 2025 MN45It is a rocky body with a diameter greater than 500 meters, which, according to the most detailed estimates, would be around 700 meters wide, a considerable size within the family of near asteroids in this range.
What has perplexed astronomers is not only its size, but its extraordinary rotation speed: it completes a revolution on its axis in just 1,88 minutesIn practical terms, it is the fastest-spinning asteroid over half a kilometer in diameter ever recorded.
These measurements were obtained by studying the changes in the object's brightness over time, a method widely used for deduce the rotation period of asteroids and other minor bodiesIn this case, the variation in light was so rapid and marked that the photometric curves left little room for doubt.
The scientific team in charge of the research, headed by the astronomer Sarah Greenstreet of the National Science Foundation (NSF) NOIRLab, analyzed these observations in detail and confirmed that 2025 MN45 breaks all known records for an asteroid of its size.
The study, published in the specialized journal The Astrophysical Journal LettersIt notes that this object is included within a small group of extremely rotating asteroids, but it is currently the most striking case due to its combination of large size and extremely rapid rotation.
What does its rotation on the interior of the asteroid reveal to us?
The speed at which an asteroid rotates can provide very valuable clues about its internal structure and its formation historyMost of these bodies are not solid blocks, but piles of rubble formed by fragments of rock held together by relatively weak gravity.
In these types of "loose" structures, if the asteroid rotates too fast, centrifugal force eventually overcomes gravitational attraction that holds the fragments together and the object eventually breaks apart. That's why there's a rotation limit, sometimes called the "spin barrier," above which most asteroids of this type cannot remain intact.
In the case of 2025 MN45, the fact that be so large and yet manage to rotate in just 1,88 minutes without disintegrating This indicates that its interior cannot simply be a pile of poorly bonded rocks. To withstand these conditions, the asteroid must be composed of a much more compact and resistant material.
The researchers suggest it could be a body monolithic or with a highly reinforced internal structurePerhaps it's the remnant of a violent collision in which only the hardest fragments survived. This scenario would fit with the idea that past impacts can accelerate the spin of some asteroids to extreme values.
Furthermore, the behavior of 2025 MN45 helps to adjust the models that describe How asteroids respond to external forces such as impacts, thermal effects, or solar radiationIn particular, processes such as the YORP effect, which can slowly modify the rotation of an asteroid due to radiation, become even more interesting in light of these kinds of findings.
An observation campaign that marks a turning point
The discovery of 2025 MN45 took place during the test campaign known as “First Look”, carried out in June 2025. This initial phase was intended to test the instrumental performance, but ended up becoming a source of spectacular scientific data.
During that campaign, the Vera C. Rubin Observatory achieved to catalog some 1.900 completely new asteroidsIn addition to observing many other known asteroids, Greenstreet's team compiled a sample of 76 asteroids with well-defined rotation periods using the obtained light curves.
Of that set, the analyses show that 16 objects exhibit very rapid rotations, with periods ranging from about 13 minutes to 2,2 hoursThis group is often called "superfast" asteroids, as they are close to the physical limits that debris structures can withstand.
Within that sample, the following were also identified: three even more extreme asteroids, with periods of less than five minutesThese cases are considered "ultrafast" and are especially rare in the observational record. Among them, 2025 MN45 stands out for combining the largest size with the shortest spin.
Project managers, such as Aaron Roodman, Deputy Director of the LSSTThey have pointed out that the ability to take such frequent images has opened a completely new window into the study of the dynamics of these celestial bodies. What has been achieved in just a few test campaigns gives an idea of the volume of discoveries that could be made when the observatory is fully operational for a decade.
Scientific impact and relevance for Europe and Spain
Beyond the curiosity aroused by an object rotating at such a speed, 2025 MN45 has direct implications for the global understanding of asteroids and for protection against potential risksUnderstanding how these objects are constructed is essential for planning effective strategies in case, in the future, it becomes necessary to deflect an object that is potentially dangerous to Earth.
The European scientific community, including the Spanish one, is closely following these kinds of findings. Several research groups in Europe are working on asteroid interior models, impact simulations, and planetary defense studies, areas that are nourished by observational data such as that provided by Rubin.
European Space Agency (ESA) missions, such as Hera, which will visit an asteroid system to study the effects of a deflection test, need realistic parameters regarding densities, resistances, and behaviors of these bodiesAn object as extreme as 2025 MN45 provides a very useful upper limit for testing these simulations.
Furthermore, the continuous flow of data generated by Rubin offers a valuable collaboration opportunity for data centers and analysis groups at European universities and observatoriesSpain, with a very active astronomical community and experience in large sky surveys, is well positioned to participate in the scientific exploitation of this type of observation.
Also from an educational and outreach perspective, the story of a giant asteroid that rotates in less than two minutes is... a very powerful resource for bringing astronomy closer to the publicThis is something that many planetariums, science museums, and European media outlets are already taking advantage of.
This discovery of 2025 MN45, achieved in an early phase of the Vera C. Rubin Observatory, has become a clear preview of the revolution expected in the study of asteroids and other minor bodies over the next few years. Its unique combination of size and rotation speed is forcing a revision of models, reinforcing the idea that there are rocky structures far more resilient than previously thought, and underscoring the importance of having telescopes capable of monitoring the sky almost continuously. As the LSST mission progresses and new data is collected, more extreme objects are likely to appear, but for now, 2025 MN45 remains the benchmark when discussing the fastest-rotating asteroid ever recorded.
