Venusian (The Astronauts)

The Venusians of Stanislaw Lem's Astronauci (known in English speaking circles as The Astronauts) are an extinct but highly advanced people. In 1908 they sent a spaceship to Earth whose mission was to irradiate the atmosphere of Earth (likely to spread sickness) in preparation for an Invasion which they referred to as 'The Great Moment'. However something happened and the ship crashed into northern Asia resulting in the Tunguska explosion. It would not be till an expedition to Venus by the communist government of Earth in 2003 that hints of what happened that day where discovered though electronic records and the ruins of the Venusian civilization. Around if not during 1908 the Venusians entered a Nuclear Civil War that destroyed their civilization- as a result Earth was never invaded.

Physiology
The Venusians only appear in the form of silhouettes burned into the side of their ruined cities. They are said to be Humanoid.

Technology
Venusians possessed electronic data storage devices in the form of spirals and also anti-gravity devices. Nuclear Missiles and other Atomic weapons where common on Venus.