The Risk Index — Our Algorithm
Our Risk Index (0–100) is a proprietary score combining five factors from NASA and JPL data. It is not an official NASA metric — it's designed to give an intuitive, at-a-glance sense of how noteworthy each flyby is.
35 pts
Earth MOID
How close the asteroid's orbit comes to Earth's orbital path. The most critical factor — a low MOID means future encounters are geometrically possible.
25 pts
Estimated Diameter
Larger asteroids carry vastly more kinetic energy. A 1km object scores maximum points — it would cause global effects on impact.
20 pts
Relative Velocity
Faster objects are more destructive on impact. Velocity at closest approach ranges from ~5 km/s to 30+ km/s for typical NEOs.
15 pts
PHA Status
NASA's official Potentially Hazardous Asteroid designation — requires MOID <0.05 AU and diameter >140m. A flat bonus when met.
5 pts
Condition Code
How well JPL knows the orbit. Code 0 = precise, code 9 = uncertain. Higher uncertainty slightly reduces the score.
Risk Scale
0–49 · Safe
50–74 · Watch
75–100 · High Risk
Most of the ~35,000 known NEOs score below 30. Objects above 75 are rare and represent asteroids with genuinely close orbital paths combined with significant size or speed.
What is Earth MOID?
Minimum Orbit Intersection Distance (MOID) is the closest possible distance between an asteroid's orbit and Earth's orbit — measured geometrically, regardless of where the two bodies actually are. It's the single most important factor in assessing long-term impact risk.
A MOID of 0.01 AU (~3.8 LD) doesn't mean an impact is imminent — it means the orbital geometry allows for very close future encounters. Whether those encounters actually happen depends on timing, which requires precise long-arc orbital solutions.
NASA uses MOID <0.05 AU as one of two criteria for the PHA classification. Our algorithm scores MOID <0.01 AU at 35/35 points.
Frequently Asked Questions
Is a high Risk Index dangerous?
Not necessarily. The Risk Index reflects how noteworthy an asteroid's characteristics are — not a probability of impact. No known asteroid is currently on a collision course with Earth.
What does PHA mean exactly?
Potentially Hazardous Asteroid — an official NASA classification for objects larger than ~140m whose orbit comes within 0.05 AU of Earth's orbital path. There are about 2,400 known PHAs. None are currently threatening.
How often is the data updated?
Our system fetches fresh data from NASA CNEOS every hour via the NeoWs API. New asteroids detected by NASA appear on this tracker within the hour.
Is this the same as NASA's Torino Scale?
No. The Torino Scale is NASA's official impact hazard scale for specific impact scenarios. Our Risk Index is a general interest score for current flybys — not a prediction of future impacts.
See the Risk Index in action
Browse all current NEOs with their Risk Index scores, orbital data, and detailed analysis.
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