NASA’s TESS mission began the first all-sky survey dedicated to finding transiting exoplanets.
The Transiting Exoplanet Survey Satellite, or TESS, launched on April 18, 2018. It searches for planets when they pass in front of their host stars and cause tiny, regular drops in measured brightness. Unlike Kepler, which observed selected fields for long periods, TESS was designed to survey nearly the entire sky.
TESS divides the sky into sectors and uses four wide-field cameras to monitor bright nearby stars. Its observations are especially valuable because planets around bright stars are easier for later ground- and space-based instruments to study in detail.
TESS has found thousands of candidate planets, many requiring follow-up observations to confirm them. The mission was not designed to photograph exoplanets directly, and a transit alone does not prove that every signal is a planet. Scientists compare repeated signals with other measurements to rule out eclipsing stars and instrumental effects.