ASTEROID FLYBY1.0× MOON

Asteroid 2026 RB39 flew past Earth

Closest approach
Map: Asteroid 2026 RB39 flew past Earth

Asteroid 2026 RB39 passed Earth on Thursday, September 17, 2026 at about 02:29 UTC, at 384,180 km (238,729 miles): 1.00 times the distance to the Moon, closer than the Moon itself. It was moving at 9.3 km/s (20,699 mph) relative to Earth and is about 5 to 11 meters (16 to 36 feet) across, judging by its brightness. NASA’s orbit puts it safely past: it posed no risk of hitting Earth on this pass.

Closest approachSep 17 02:29 UTC
Distance384,180 km · 238,729 mi
Lunar distances1.00
Speed9.3 km/s · 20,699 mph
Size (est.)5–11 m
Brightness (H)28.7
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Its orbit

It is an Apollo asteroid: its orbit is larger than Earth’s but crosses it. It circles the Sun once every 1.7 years. Astronomers first spotted it on September 15, 2026, just 2 days before its closest approach.

How often does this happen?

Small asteroids pass between Earth and the Moon every few weeks; most are only a few meters to tens of meters across and are found days before, or even after, they fly by. For scale, the rock that exploded over Chelyabinsk, Russia, in 2013 was about 18 meters across.

Did you know?

The Moon is leaving. The Moon drifts about 3.8 cm farther from Earth every year, measured with lasers bounced off mirrors left by Apollo astronauts.

Data: NASA JPL Small-Body Database and CNEOS close approaches. Size assumes a reflectivity between 5 and 25 percent.

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