Planetary defense scientists detected an asteroid crashing into Earth off the coast of Australia this week, and only had a 6-hour warning that it would impact. On Sunday, September 6, 2026, self-tracking telescopes at the Mount Lemmon Observatory in Arizona, USA, captured a faint object crossing the sky. The object turned out to be an asteroid measuring just 80 cm (2.6 feet) across, astonishingly small considering the Earth-based observatory spotted it among the background stars before crashing into the ocean. Credit: Puchan/Getty Images Mount Lemmon Observatory in Arizona, United States. Credit: John Davis/Stocktrek Images/Getty Images Six hours after its discovery, the asteroid, provisionally designated CERNQ52, burned up as it entered the Indian Ocean off the northwest coast of Australia at 16:07 UTC, according to preliminary results released by the European Space Agency. While the event produced no damage or craters, planetary defense experts will consider this detection a success. Now officially designated 2026 RW1, it is only the 13th known impacting asteroid ever detected before hitting Earth. A needle in a haystack of space rocks We’re all used to seeing infographics of huge asteroids that could wipe out entire neighborhoods on Earth in an instant. But finding one that measured just 80 centimeters in diameter before hitting Earth is truly extraordinary. Small asteroids enter Earth’s atmosphere all the time, but it’s rare to detect them before they collide. 2026 RW1 marks only the 13th time humanity has detected an asteroid prior to its entry into the atmosphere. The Catalina Survey at Mount Lemmon Observatory uses automated telescopes to scan areas of the night sky, looking for fast-moving objects that could indicate an asteroid, comet or other rocky body moving through space. It’s not a new technique: Astronomers have long compared images of the same patch of sky taken at different times to detect fast-moving foreground objects. Clyde Tombaugh photographed on a Zeiss Blink Comparator, a machine used in the discovery of Pluto. Credit: Lowell Observatory Archives The technique was used by Clyde Tombaugh to discover Pluto in 1930, for example, but back then astronomers had to carry out the painstaking work manually, using photographic plates and a “blink comparator” to identify objects that moved between exposures. Astronomers now have automated telescopes that often adopt machine learning and artificial intelligence to make the task of finding potentially dangerous space rocks much easier. Once 2026 RW1 was detected, the European Space Agency’s (ESA) Meerkat system, another automated warning system, went to work studying the asteroid, predicting its trajectory and the moment of impact. The asteroid CERNQ52 entered the Earth’s atmosphere today over the ocean south of Indonesia. It was discovered by the Mount Lemmon Survey in Arizona just hours before its disappearance. At 80cm wide it wouldn’t have caused any damage. I had to exaggerate the size here so you could see it. 🔭 pic.twitter.com/kJGBjqwI2d — Tony Dunn (@tony873004) September 6, 2026 A rare Aten asteroid Space rock experts such as Adrian Coffinet (as reported by EarthSky) have suggested that 2026 RW1 could be a rare type of asteroid known as the ‘Aten’ asteroid. Aten asteroids are a type of near-Earth asteroid whose orbit around the Sun takes them within the Earth’s orbit. However, they sometimes cross Earth’s orbital path, potentially bringing them closer to our home planet. While this may seem quite alarming, it’s worth remembering that asteroids crash into Earth’s atmosphere and burn up all the time. Furthermore, what the detection of 2026 RW1 shows is that humanity’s ability to detect tiny objects approaching Earth is improving all the time, meaning our automated systems are becoming reliable early warning systems. Summary A small asteroid, temporarily designated CERNQ52 and later named 2026 RW1, was detected by the Catalina Sky Survey on September 6, 2026, just hours before it entered Earth’s atmosphere. The asteroid, which measured 80 cm in diameter, disintegrated over the Indian Ocean off northwest Australia without causing damage or reaching the ocean surface. Its detection marks only the 13th known occasion that an asteroid has been detected before entering the atmosphere, making it a notable success for planetary defense. The event shows how automated systems like ESA’s Meerkat can help provide warnings about potentially dangerous space rocks.
