Large Asteroid to Pass Earth, Visible in Small Telescopes Today

A 200-meter-wide asteroid will pass within 1.9 million miles of Earth on July 25, 2024, offering amateur astronomers a rare opportunity to observe it through small telescopes, according to EarthSky. The near-Earth object, designated 2024 MK, poses no collision risk but marks the closest approach of an asteroid of this size in years, astronomers say.

EarthSky reports that 2024 MK will reach peak brightness around magnitude 12.5—bright enough for telescopes with apertures as small as 6 inches under dark skies. The asteroid was discovered on June 16, 2024, by the Minor Planet Center, a clearinghouse for asteroid and comet observations, and has since been tracked by observatories worldwide. NASA’s Center for Near-Earth Object Studies (CNEOS) confirms the July 25 flyby, noting that while 1.9 million miles is well beyond the Moon’s orbit, it is unusually close for an object of this size.

Why does this flyby matter? Astronomers cite two key reasons. First, 2024 MK’s proximity provides a rare chance to study a potentially hazardous asteroid (PHA) up close without relying on spacecraft. Second, the event underscores the importance of global asteroid-tracking networks, which have identified thousands of near-Earth objects in recent decades. “This is a good reminder that our solar system is dynamic, and we’re getting better at detecting these objects early,” said Paul Chodas, director of CNEOS, in a statement to EarthSky.

Not all near-Earth asteroids are this accessible. For comparison, the much larger 3200 Phaethon—responsible for the annual Geminid meteor shower—passed within 6.4 million miles of Earth in December 2023, but its size (5.1 km wide) made it visible only to professional observatories. Meanwhile, smaller objects like 2024 MK (estimated at 200 meters) are more common but rarely approach so closely. The last similarly sized asteroid, 2019 OK, flew by at 41,000 miles in July 2019—a distance closer than many satellites—but was discovered just days before its closest approach, highlighting gaps in detection capabilities.

For amateur astronomers, the July 25 event offers a practical test of equipment and skills. EarthSky advises observers to use star charts from services like Stellarium or The Sky Live to locate the asteroid, which will move rapidly against the background stars. The Virtual Telescope Project, an online observatory, plans a live stream of the event, providing an alternative for those without telescopes.

What comes next? NASA’s DART mission, which successfully demonstrated asteroid deflection in 2022, remains a priority for planetary defense. Meanwhile, the NEO Surveyor spacecraft, set to launch in 2027, aims to improve early detection of smaller objects like 2024 MK. “This flyby is a low-risk but high-value opportunity to practice our response,” said Lindley Johnson, NASA’s planetary defense officer, in a 2023 interview with Space.com.

While 2024 MK’s visit is harmless, it serves as a case study in how quickly astronomers can characterize a newly discovered object. The Minor Planet Center logged over 100 observations of the asteroid within days of its discovery, a testament to the global network of observatories. For context, the European Space Agency’s Space Safety program tracks over 30,000 near-Earth objects, with roughly 1,000 new discoveries added annually.

Observers in the Northern Hemisphere will have the best view, as the asteroid will be visible in the constellation Pisces during its closest approach. Cloud cover or light pollution may limit visibility for some, but EarthSky notes that even urban areas with moderate light pollution could spot the object with larger telescopes. The next opportunity to observe an asteroid of this size won’t come until 2025, when 2006 QV89—a similarly sized object—makes a distant pass at 4.2 million miles.

For those unable to observe directly, NASA’s Asteroid Watch dashboard provides real-time tracking data, while the Asteroid Day organization offers educational resources on planetary defense. The event also coincides with the annual Asteroid Day on June 30, which raises awareness about asteroid impacts and mitigation efforts.