Astronomers discovered 19 ultra-fast rotating asteroids, some of which rotated in less than 2 minutes!
Asteroids. We know this object as debris that failed to form a planet between Mars and Jupiter. But, asteroids are not only between Mars and Jupiter. These small objects also exist near Earth and we know them as near-Earth asteroids. The number is in the millions and it is even estimated that it could reach billions. Some have potential danger to the Earth, some don’t.
Of course, astronomers carry out routine monitoring through various survey projects, including ATLAS (Asteroid Terrestrial-impact Last Alert System) and the Catalina Sky Survey. The plan is that in early 2026, the Vera C. Rubin Observatory, which was established on a peak in Cerro Pachón, Chile, will also begin operating.
The 8.4 meter Simonyi Survey Telescope at the observatory is equipped with the largest digital camera. This telescope will photograph the sky repeatedly for 10 years and map the night sky. Inevitably, there will be many new discoveries and stories from the Rubin Observatory.
Discoveries from First Observations
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Before starting full operation in 2026, the Simonyi telescope at the Vera C. Rubin Observatory has made its first observations and released the results in June 2025.
In just 10 hours of observations, the Simonyi Telescope managed to photograph nearly 4000 asteroids, 1900 of which were asteroids that had never been detected before. Most of these asteroids are in the Main Asteroid Belt, between Mars and Jupiter. But some are in the area near Earth and there are also those in the outer edge of the Solar System.
The discovery of this asteroid came from 10 hours of observations carried out over 7 days in April/May. Because the shape of an asteroid is not a perfect ball or irregular, its brightness will appear to fluctuate or brighten and then dim as this object rotates. This happens because when rotating there are times when the observer sees a wide side that reflects a lot of light and then a narrower area that appears dimmer. From this change in brightness, astronomers can find out the rotation period or the time it takes for an asteroid to complete one rotation.
Among these new asteroids, there are asteroids that rotate very quickly. It only takes less than two minutes! The time is very fast, even too fast to brew coffee.
But that was a pleasant surprise from the results of the first observations from the Rubin Observatory. The results of direct observations produce accurate astronomical data in the time domain, of course in high resolution. Imagine what kind of data we will receive when the Simonyi Telescope begins its 10-year survey of scanning the southern sky. A series of stories that reveal the story of objects in the universe.
One thing is certain, the Simonyi Telescope equipped with an LSST camera will be a discovery machine that reveals objects in the Universe.
Fast Rotating Asteroids
Asteroids are not just chunks of rock that wander around the Sun. The asteroid’s rotation and orbit preserve records of its formation billions of years ago, of past collisions, composition, and how gravity and time reshaped the architecture of the Solar System over billions of years.
Fast rotating asteroids are thought to have accelerated due to collisions with other asteroids in the past. And it could be a fragment of a larger object. Apart from that, the effects of solar radiation can also slowly accelerate the rotation of asteroids over a period of millions of years.
Apart from that, such fast rotation indicates that the asteroid is very sturdy, that is, it has very strong attachments or glue so that fragmentation does not occur, or it does not fall apart.
Why is that?
Most asteroids are piles of debris formed from small rocks and dust that combine and are bound together by gravity. However, the small mass of the asteroid results in weak gravity, meaning that the attachment of the rock debris that makes it up is not strong or loose. Therefore, if this asteroid rotates too fast, with a loose density, the asteroid will easily be scattered.
Asteroids that spin quickly and complete one rotation in 2.2 hours will not be destroyed. And this is the fastest limit for asteroid rotation rates, especially in the Main Asteroid Belt region. If something rotates in less than 2.2 hours, aka even faster, then the asteroid has a stronger structure, with a larger size and stronger forming material.
Ultra Fast Asteroids
Of the 1900 new asteroids in the Vera Rubin Observatory’s inaugural observations, there were 76 asteroids with interesting rotation rates. Among them there are 16 asteroids rotating super fast between 13 minutes and 2.2 hours. These 19 asteroids with super fast rotation are longer than a football field.
What’s even more surprising is that there are three asteroids that rotate in less than five minutes! If we could set foot there, that would mean a day on this asteroid would have passed in less than 5 minutes!
But there is one asteroid that is unusually fast. Introducing, 2025 MN45. An ultra-fast asteroid that only takes less than two minutes to complete one rotation. More precisely, the 2025 MN45 only takes 1.8 minutes to rotate and is almost 7 times the size of a football field. This combination places 2025 MN45 as the asteroid with the fastest rotation rate for an asteroid with a diameter of more than 500 meters.
Astronomers suspect that 2025 MN45 has a rock composition that is dense and sturdy so that it does not crumble when it rotates that fast. This is certainly surprising because asteroids are usually composed of small rocks and dust that joined together due to gravitational interactions during the formation of the Solar System.
Some rapidly rotating asteroids are part of the Near Earth Objects. That’s not to say that objects like this don’t exist in the Main Asteroid Belt. The main belt’s distant location between Mars and Jupiter means these small objects are much fainter and more difficult to observe.
However, the presence of the Rubin Observatory sets a new frontier in the search for rapidly rotating asteroids.
Almost all of the rapidly rotating asteroids discovered this time are in the Main Asteroid Belt, with some of them being on the outer edge of the belt. Only one was identified as originating from a near-Earth object. Once again, the presence of the Rubi Observatory broke a new record.
Apart from 2025 MN45, other asteroids whose rotation rate is less than 5 minutes are: 2025 MJ71 with a rotation speed of 1.9 seconds, 2025 MK41 (3.8 minutes), 2025 MV71 (13 minutes), and 2025 MG56 (16 minutes). These 5 asteroids have a diameter of several hundred meters and are included in the group of sub-kilometer Near Earth Objects that rotate very quickly.
Achievements of the Rubin Observatory
These results clearly raise questions about these asteroids. How was it formed and what mechanism keeps this asteroid intact if its composition is a combination of small rocks.
The first observations from the Rubin Observatory succeeded in setting new limits for achievements in the world of astronomy, especially observations of the Earth’s shelf. The initial observation results demonstrate the Rubin Observatory’s ability to produce more data in the future. Better mapping of objects in the Solar System, collision history, as well as information on the formation of the Solar System and its evolution, could be a new story to complement the story we already know.
Asteroids that spin too fast are a valuable puzzle, because they force us to reexamine old assumptions. If many asteroids are rubble piles, why do some large ones remain intact under such rapid rotation? Are some asteroids more “rock solid” than we thought? Or is there another process that strengthens them? These kinds of questions are the reason why the “record” doesn’t stop at the numbers. Records are often spotlights that signal there’s a part of the Solar System’s story we don’t yet understand.