The animation illustrates the observation of TRAPPIST-1 c. It starts with a top view of the planetary system of TRAPPIST-1 and then rotates to the perspective as observed from Earth. We see the primary and secondary eclipses as the planet passes in front of the star and then disappears behind it, respectively. Finally, the signature of the illuminated day side before and after it is eclipsed by the star becomes clear as time progresses. The brightness shift during and outside the eclipse encodes the infrared radiation produced by the planet and its possible atmosphere.
More information in the press release “Searching for an atmosphere on the rocky exoplanet TRAPPIST-1 c”.