He figured the light could be flashed on and off to encode a message.A light-based "Morse code" was also considered by the British statistician Francis Galton in 1896.
With its 1,000-foot reflector dish, the Arecibo Observatory in Puerto Rico is the world's largest single-dish radio telescope and most powerful radar.
Frank Drake used it in 1974 to send the first CETI message.
The desire to contact intelligent life on other planets is much older than the UFO craze and the SETI movement.
Several 19th century scientists contemplated how we might communicate with possible Martians and Venusians."As early as the 19th century, inventors imagined "sky telegraph" equipment to communicate with the supposed inhabitants of the solar system's planets," Raulin-Cerceau recently wrote with her colleague in the French magazine Pour la Science.
It is now generally assumed that radio is a more suitable means of extraterrestrial communication.
Radio waves are less affected by cosmic dust than visible light, and there is less of a radio background to deal with in the sky.
Two of radio's pioneers showed interest in interplanetary radio communication.
The first of these inventors was Carl Friedrich Gauss, the German mathematician.
In the 1820s, he spoke of reflecting sunlight towards the planets with his land surveying invention, the heliotrope.
He is also credited with the idea of cutting a giant triangle in the Siberian forest and planting wheat inside.
In 1869, the French inventor and poet Charles Cros imagined using a parabolic mirror to focus the light from electric lamps towards Mars or Venus.