Asteroid 2025 YK4 flew past Earth at 0.93 LD on December 20, 2025

Asteroid 2025 YK4, a near-Earth object in the Apollo class, flew past Earth at a minimum distance of 0.93 lunar distances (LD) or 0.00238 astronomical units (AU), equivalent to approximately 356 500 km (221 600 miles), at 16:34 UTC on December 20, 2025. The relative velocity at the moment of closest approach was measured at 13.53 km/s.

Based on its absolute magnitude (H) of 25.923, the estimated diameter of 2025 YK4 ranges from roughly 18 to 40 m (60 to 130 feet), depending on albedo assumptions commonly used for small near-Earth asteroids.

2025 YK4 is classified within the Apollo group, exhibiting an orbital eccentricity of 0.373 and a semi-major axis of 1.34 AU. Its perihelion distance is 0.841 AU, and the inclination of its orbit is 17.5 degrees. This reflects a moderately eccentric and inclined orbit typical of Apollo-type near-Earth asteroids.

As of now, no direct albedo measurement is reported, and the asteroid is not classified as potentially hazardous (PHA) based on available criteria.

The asteroid was first observed on December 22, 2025, and last observed on December 24, suggesting a very short observational arc. Its current orbit solution carries a condition code of 7, indicating an uncertain or preliminary trajectory that may be refined with further observations.

Several other recent close approaches of objects within 1 lunar distance include asteroid 2025 YQ2, which passed at 0.68 LD at 06:14 UTC on December 19, 2025, with an estimated size of approximately 4–9 m (13–30 feet), and 2025 YE2, which flew past at 0.24 LD at 15:21 UTC on December 18, 2025, with an estimated diameter of around 7–15 m (23–49 feet).