Bus-sized asteroid makes close approach to Earth Monday at quarter-lunar distance

An asteroid roughly the size of a school bus will slip past Earth on Monday, passing within 91,593 kilometers—about a quarter of the distance to the Moon. The object, designated 2026JH2, was discovered just eight days earlier by astronomers at Mount Lemmon Observatory in Tucson, Arizona, on May 10. It belongs to a class of asteroids called Apollo objects, whose orbits cross Earth's path around the Sun.

The closest approach will occur Monday evening at 6 p.m. Eastern time, or 8 p.m. in Brazil. At that moment, the asteroid will be roughly 24 percent of the Earth-Moon distance away—and more than two and a half times farther out than the geostationary satellites that handle telecommunications and weather forecasting for the planet. Despite the proximity in cosmic terms, there is no danger. Richard Binzel, a planetary scientist at MIT and inventor of the Torino Scale, a tool for assessing potential asteroid collisions, confirmed the passage will be entirely safe. He noted that such encounters are routine: car-sized objects pass between Earth and the Moon every week, and school-bus-sized asteroids drift through our neighborhood several times a year. Only recently have survey instruments become sensitive enough to detect them. Before these advances, such objects simply went unnoticed.

The asteroid originated in the belt between Mars and Jupiter, where occasional collisions combined with Jupiter's gravitational pull can send smaller asteroids toward Earth—a process well understood for decades and known to affect thousands of near-Earth objects. Yet the exact size of 2026JH2 remains uncertain. When an optical telescope observes a new object, it measures only the light the object reflects or emits in visible wavelengths. There is no way to know how much light the object absorbs versus reflects. Patrick Michel, an astrophysicist and research director at France's National Center for Scientific Research, explained that determining size would require infrared observations, since infrared brightness correlates directly with size. But such observations are difficult to conduct from Earth and are not used in the initial discovery process. Based on estimates of reflected light, 2026JH2 is thought to measure between 15 and 30 meters across. At the lower end of that range, it would be comparable to the fireball that exploded over Chelyabinsk, Russia, in 2013, shattering windows and injuring a thousand people. At the upper end, it would approach the size of the object that detonated near the Podkamennaya Tunguska river in Siberia in 1908, flattening vast stretches of forest. Unlike those two events, however, 2026JH2 will not enter the atmosphere, so there is no risk of explosion.

Michel emphasized that while the passing distance seems remarkably close, it remains "sufficiently far that there is absolutely nothing to worry about." He did note that predicting the asteroid's future trajectory is difficult and cannot rule out a collision at some point. The reassuring news, he added, is that no known asteroid poses a threat within the roughly century-long window of current predictive capability. A far more dramatic encounter awaits in 2029, when an asteroid called Apophis—at least ten times larger than 2026JH2—will pass just 32,000 kilometers from Earth. Michel expressed excitement rather than concern: such a close approach by an object so large occurs only once every few thousand years, and its light will be visible to the naked eye across Europe, Africa, and parts of the Middle East. By contrast, 2026JH2 will require small telescopes in dark-sky locations to observe, remaining one hundred times too faint for unaided vision.

Jean-Luc Margot, a professor of Earth, planetary, and space sciences at UCLA, pointed out that detailed information about the asteroid is limited partly because planetary radar capabilities are currently degraded. The Arecibo telescope collapsed in 2020, and NASA's Goldstone antenna has been offline for extensive repairs. Without radar data, scientists have less ability to assess impact risk and remain more vulnerable to the threat of collision. A partial live stream of the close approach will be provided by the Virtual Telescope Project using instruments in Italy, beginning at 3:45 p.m. Eastern time and continuing as long as the object remains visible from that location. Margot noted that astronomers have catalogued only about one percent of near-Earth asteroids the size of 2026JH2, so it is unsurprising that this object was discovered only days before its closest approach, when it became bright enough for asteroid surveys to detect. He acknowledged concern about the incomplete inventory of near-Earth objects, but noted that space agencies are now actively funding discovery research to improve our catalog of potentially hazardous asteroids.