Dangerous Space
This is the text version of the interactive 3D documentary. 한국어
Danger ranking › Impact threats
1979 XB
Impact threats #4 · Nobody has seen it since 1979 — very unlikely to hit, but big
View in 3D- Name
- 1979 XB
- Type
- Near-Earth asteroid (lost)
- Size
- About 660 m across (estimated)
- Distance
- 320 million km from Earth · light takes 18 min 4 s (Position on 2026-11-04 · JPL Horizons)
#4 of 2,230 on NASA/JPL’s Sentry risk table · as of 2026-11-04
The story in 1 scene
Missing for over 40 years
This asteroid was watched for a few days in December 1979 and never confirmed again. Its chance of hitting Earth is very small — about 1 in 1.2 million — but because it is about 660 m wide it ranks fourth on the Palermo scale. Its position on screen is calculated from the 1979 observations and may be far off.
Why?The Palermo scale looks at more than probability. It also counts how much energy an impact would release and how long we have, and compares that with the normal background risk for the same period.
What nextTelescopes that sweep large areas of sky quickly, like the Vera C. Rubin Observatory that started observing in 2025, could find it again.
See this scene in 3D →Sources
NASA/JPL CNEOS Sentry impact risk table · JPL Small-Body Database: 1979 XB
Impact-threat rankings and probabilities follow NASA/JPL’s Sentry risk table (as of 2026-11-04). The other categories are editorial rankings using the published criteria. Distances to stars can carry large uncertainties.