A giant spaceship hovers over the horizon. A representative of mankind steps out of her home, raises her eyes to the ship, and says — exactly what? Recently, scientists have explored the options for responding to an extraterrestrial’s hello. Space.com reports that if aliens were to come knocking at our door, we would have a variety of ways to knock back.

Scientists have long played with the idea of extraterrestrial communication. One thing is certain — whoever they are, they probably won’t speak English, French, or the latest Valley Girl dialect coming out of Hollywood. Douglas Vakoch is director of Interstellar Message Composition at the SETI Institute. As he told Space.com, "It's very reasonable to think that we will know there's an extraterrestrial out there, that we will have a message that is distinctly artificial, but that we won't be able to decipher it." 

So what to say, and how to say it? The SETI Institute recently solicited ideas from the public on how to compose the best message for extraterrestrials. Some suggested a language based on mathematics, as experts feel that any alien race capable of communicating with us would be capable of deciphering our mathematical system. Others felt we should just send out all our images from Google and let the aliens figure out the common language. The idea is that aliens would have an idea of how we live on a day-to-day basis, and that they would find it intriguing.

But others feel we should put our best foot forward, citing the example of the Voyager spacecrafts. In 1977, a collection of sounds and images were put aboard the Voyager 1 and 2 spacecrafts and sent out into space. This was a compilation of sounds, images, music and culture from around the world. Vakoch points out that these images represent a more positive aspect of humanity. As he told Space.com, "I think the richest description of ourselves that has been sent into space is the Voyager interstellar records. They include greetings in 55 languages, over a hundred pictures describing life on Earth." Recently, both Voyagers crossed out of our solar systems and into deep space. 

For further reading: How should earth respond when aliens say hello?