Near-Earth Objects Today

What are near-Earth objects and how are they tracked?

A near-Earth object (NEO) is an asteroid or comet whose orbit brings it within 1.3 astronomical units of the Sun — close enough to Earth's orbit to be of interest for tracking. NASA's Center for Near-Earth Object Studies (CNEOS) maintains a catalogue of more than 35,000 known NEOs, with new discoveries added every week by surveys like Catalina, Pan-STARRS, and NEOWISE.

Astronomers measure how close an asteroid passes in lunar distances (LD) — the distance from Earth to the Moon, about 384,000 km. An object passing within 0.05 AU (roughly 19.5 LD) that is also larger than 140 metres is classified as a potentially hazardous asteroid (PHA). This classification flags objects worth long-term monitoring — it does not mean an impact is expected.

Ground-based telescopes scan the sky each night, discovering new objects and measuring their positions. NASA JPL's Small-Body Database uses these observations to compute precise orbits and predict close approaches decades into the future. Flarient pulls this data directly from JPL's CNEOS feed and displays the nearest upcoming approaches in real time.

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