The Alanians are a race of intelligent beings on the Third Planet from Altair. They are gray, about four feet in height, and have perfectly round heads atop a squat body, supported by four legs. They have two spindly arms which they swing like antennae.
The Alanians were forced to mostly abandon their planet due to antimatter storms which threatened to annihilate their world. Some left in starships, while others remained on the planet protected by crystalline domes. The ones who left headed for a friendly planet in another star system -- Earth.
As they left, they sent out a message to Earth. The message was incomprehensible to the people of Earth but the meaning was "We are coming". ("The Third Planet from Altair")