Eiffel Tower-sized asteroid 2021 MJ to pass by in 9 hours
Asteroid 2021 MJ will pass at roughly 49× the distance to the Moon around 2026-07-27 17:33 UTC. This is a routine close approach with no known impact risk.
How close is close?
Astronomers measure near-Earth passes in lunar distances (LD) — the ~384,000 km between Earth and the Moon. A pass inside 1 LD sounds alarming but still usually means a miss by tens or hundreds of thousands of kilometers; even the geostationary satellite belt sits only 0.09 LD up. "Close" in planetary terms is still very, very far in human terms — and every object listed here has a well-determined orbit that rules out impact on this pass.
How often does this happen?
Small asteroids pass inside the Moon’s orbit far more often than most people assume — car-sized objects do it many times a year, house-sized ones several times a year. What’s changed is not the sky but our ability to see it: modern survey telescopes now catch objects that would have passed unnoticed a generation ago. The headline-generating passes are usually discoveries of the ordinary, not omens of the extraordinary.
Who keeps watch?
Survey telescopes (Catalina Sky Survey, Pan-STARRS, ATLAS, and now Rubin Observatory) discover new near-Earth objects nightly. The Minor Planet Center collects the observations, and NASA JPL’s Sentry system continuously recomputes impact probabilities for every object that could conceivably pose a risk. When a close approach appears in this app, its trajectory has already been checked against decades of future orbits.
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