Glossary

Light curve

A graph of an astronomical object's brightness measured repeatedly over time, used to detect transits, flares or pulsation.

A light curve is a plot of an astronomical object's measured brightness against time, built from repeated observations of the same target rather than a single snapshot.

It is produced through photometry, repeatedly measuring a star's or object's flux, and analyzed for periodic dips that suggest a planet transiting its star, sudden brightening from a flare or supernova, or slow trends such as a variable star's pulsation cycle. This differs from a spectrum, which captures brightness across wavelengths at one moment, a light curve instead captures one brightness measure tracked continuously across time.

Light curves are the primary tool for detecting exoplanets through the transit method and for classifying variable stars and transient events, and large astronomical survey data programs now generate them automatically for millions of objects. The main pitfall is distinguishing a genuine astrophysical signal from instrumental noise or weather-driven variation, a task that borrows heavily from general signal processing; sparse or irregularly timed observations can also alias a true periodic signal into an apparent but incorrect period, so candidate detections need independent confirmation before being trusted.

Last reviewed September 22, 2026

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Related terms

Photometry Measuring the brightness or intensity of light from an object, most commonly a star or other astronomical source. Astronomical survey data The large, systematically collected datasets produced by telescopes that repeatedly scan wide areas of the sky. Signal processing Techniques for analyzing, filtering, and transforming time-varying signals, such as sensor readings or audio, to extract or clean up information. Anomaly detection Identifying data points or patterns that deviate significantly from expected or normal behavior. Time series forecasting Predicting future values of a metric using patterns found in its own historical sequence over time.