But how visible are we to aliens that are farther away? In the early
nineteenth century, the Austrian physicist Joseph von Littrow is said
to have suggested digging giant geometric shapes in the Sahara Desert
as signaling devices. The excavations would be filled with water and
kerosene, and set afire at night to get the attention of our Martian
brethren. The desert figures were to be roughly 20 miles across. So to
make out these patterns from the Red Planet would require a 10-meter
Keck-size telescope perched on top of, say, Olympus Mons (where the
effects of atmospheric "seeing" would be minimal). If sophisticated
Martians existed, they could presumably build such an instrument and
admire von Littrow's flaming trench work.

hehe why bother
the amount of noise this planet makes from radio emissions (tv, radio, etc)
should get the attention of anyone passing by if we like it or not ??