This is the 50th known asteroid to fly past Earth within 1 lunar distance since the start of the year. It is also the 3rd closest so far this year and the 7th closest over the past 12 months.
2025 HH was first observed at Catalina Sky Survey, Arizona, on April 18 — about 9 hours after it made a close approach to our planet.
The object belongs to the Aten group of asteroids and has an estimated diameter between 1.9 and 4.2 m (6.2 – 13.8 feet).
The Aten asteroid group is a class of near-Earth asteroids characterized by orbits that bring them close to or across Earth’s path around the Sun. These asteroids have a semi-major axis of less than 1 AU, meaning their average distance from the Sun is shorter than Earth’s, but their aphelion extends beyond 0.983 AU, allowing them to cross Earth’s orbit.
This group includes objects that are often difficult to detect due to their position relative to the Sun, frequently remaining in the daylight sky from Earth’s perspective.
Their Earth-crossing trajectories and proximity to our planet categorize some members of the group as potentially hazardous.
References:
1 Asteroid 2025 HH – Minor Planet Center – Accessed on April 21, 2025
2 Asteroid 2025 HH – CNEOS – Accessed on April 21, 2025