TLE (two-line element set)
A TLE (two-line element set) is a compact, standardized text format that encodes a satellite's orbit at a specific moment in two 69-character lines.
Published by US Space Force / NORAD and CelesTrak, TLEs feed the prediction models that compute where any tracked object will be.
Each set carries the orbit's inclination, eccentricity and other elements plus an epoch time, and it must be refreshed regularly because orbits drift.
See it live on Cosmik
Related terms
- SGP4 — SGP4 is the standard mathematical model that turns a satellite's TLE into a predicted position and velocity at any given time.
- Orbital period — The orbital period is the time a satellite takes to complete one full orbit, set almost entirely by its altitude.
- Ground track — A ground track is the path traced on Earth's surface directly beneath a satellite as it orbits.
