Asteroid the size of a New York skyscraper to skim past Earth in hours, no immediate threat

An asteroid the size of a New York City skyscraper will pass within about 520,000 miles of Earth in the early hours of Thursday, a close approach that poses no immediate danger. The object, designated 2025 FA22, is set to drift by at about 3:40 a.m. ET on Sept. 18. That distance is roughly twice the space between Earth and the Moon, a separation far enough to avoid a collision but close enough to be studied in detail with Earth-based telescopes. Scientists first spotted 2025 FA22 with the Pan-STARRS 2 telescope in Hawaii, and early assessments warned that the rock might strike Earth when it travels through this region of the solar system again in 2089. Since then, observations have refined its path and trajectory. The rock is hurtling through space at about 24,000 miles per hour, a pace that would allow it to cross the continental United States in under 15 minutes if a direct collision were possible. It will not be visible to the naked eye, but a backyard telescope with an eight-inch aperture or strong stargazing binoculars should detect it as a faint, moving point of light during its closest approach.

The close approach occurs as astronomers prepare for more precise measurements of its orbit and physical properties. The asteroid measures between about 427 and 951 feet across, making it roughly as large as the Chrysler Building. Based on current orbital data, 2025 FA22 will make additional near-Earth passes in 2089 and again in 2173. In 2173, it is predicted to come within roughly 200,000 miles of Earth, a distance still considered a close approach in space terms but not a threat to the planet this year. The European Space Agency has noted the current trajectory does not pose a danger for Thursday morning, even as researchers view the event as an opportunity to refine tracking techniques and improve risk assessments for future objects.

The 2025 FA22 flyby offers a practical test for ongoing monitoring networks. Astronomers will measure the asteroid's position, motion, and brightness to better understand its shape, surface features, and composition. In particular, a team led by ESA researcher Maxime Devogele is studying how sunlight reflects off the asteroid to infer whether it is rocky or metallic, how rough or smooth the surface is, and how reflective it may be. Such measurements help scientists gauge how an object interacts with sunlight, which in turn informs any potential mitigation strategies for a future threat. The data gathered this month are expected to feed models that could guide deflection or disruption plans should a similarly sized object be on an impact trajectory with Earth in the future.

Public observers can tune in to a livestream of the flyby. The Virtual Telescope Project has arranged a free broadcast starting Wednesday night at 11 p.m. ET that will cover the entire pass of 2025 FA22. While the ESA has concluded that there is no current threat from this asteroid, researchers emphasize that Thursday's close approach is valuable as a rehearsal for a more dangerous scenario. In the end, the event underscores the ongoing work of international space agencies to detect, characterize, and, if necessary, mitigate near-Earth objects before they pose a risk to the planet.