Near-Earth Asteroid Tracker

Live close approach data from NASA · Updated hourly

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Asteroid: 138971 (2001 CB21)

Potentially hazardous 2026-Sep-29 07:18 UTC

Potentially hazardous by NASA classification — Classified hazardous by NASA due to its size — passing safely. No known asteroid poses an impact risk in the next 100+ years.

Historical context

This object passes within 21.05 LD of Earth. Approaches this close (within 22 LD) are recorded several times per month across all tracked near-Earth objects.

Size comparison

Estimated diameter: 521–1164m — the width of a small town.

If it were to strike Earth (it won't), the estimated impact energy would be approximately 7,828 megatons of TNT.

Closest distance
21.05 LD
8.1 million km
Relative velocity
10.23 km/s
36,822 km/h
Diameter estimate
~842m
521–1164m range
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