As part of its ongoing efforts to promote every single Pokémon out there, The Pokémon Company has shared special content dedicated to Ampharos:
Did you know? The light from its tail can be seen from space. This is why you can always tell exactly where it is, which is why it usually keeps the light off. Its tail shines bright and strong. It has been prized since long ago as a beacon for sailors.
Source: The Pokémon Company