Animation: The Bat Shadow’s “Flapping” Motion Explained

This animation depicts how the “flapping” motion of the shadow of the star HBC 672 has been observed by the NASA/ESA Hubble Space Telescope.

The star is believed to be surrounded by a warped, saddle-shaped disc with two peaks and two dips. A planet embedded in the disc, inclined to the disc’s plane, may be causing this warping. As the disc rotates around the young star, it blocks the light from that star and casts a varying, “flapping” shadow on a distant cloud.