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Field report · Asteroid 2024 YR4

Seven Years Out, YR4’s Moon Question Is Still Open

Exactly seven years before YR4’s close pass, its 4.3% lunar-impact estimate remains an unusual open question in the night sky.

Seven years from today, 2024 YR4 will sweep through the Earth–Moon neighborhood. The leading estimate still gives it a 4.3% chance of meeting the Moon—roughly 1 chance in 23—and a 95.7% chance of passing by.

That small possibility has stayed with us because YR4 has become extraordinarily faint. The asteroid is now too distant for ordinary ground-based follow-up, rather like a charcoal pebble vanishing down an unlit road. Astronomers expect it to become comfortably observable again in 2028, when a new set of positions should tighten the forecast.

Until then, the uncertainty is part of the story. A lunar impact would not threaten Earth or shove the Moon from its orbit. It would make a new crater while telescopes watched, giving planetary scientists a rare before-and-after experiment. A close miss would be compelling too: a building-sized asteroid threading the space around our nearest neighbor. Either way, December 22, 2032, has earned a small circle on the astronomy calendar.

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