A mysterious radio signal from a distant planet has sparked excitement among astronomers, hinting at the tantalizing possibility of extraterrestrial life.

disc signals, dwarf signals, lower- and upper-quadrant semaphores, motor-car signals, position-light signals, searchlight signals, and smashboards. Check out "Railroad signals 101", "Train signals ...

A red dwarf star, paired with a white dwarf ... The discovery adds to an enigmatic group of stars emitting long-period signals, raising questions about their frequency in the Milky Way.