Scientists in the US have said it is time to try and contact intelligent life on other worlds.
Researchers involved in the search for extra-terrestrial life are considering what the message from Earth should be.
The call was made by the Search for Extra Terrestrial Intelligence institute who've been listening for space signals for over 30 years.
Scientists are now going work out what the message will be and what to do if there were ever an answer.
So far there has been no sign of ET.
What would you say to an alien?
We asked you what message you would send to aliens if they were discovered. This chat page is now closed but you can read a selection of your comments below.
I would tell them what people eat here on Earth.
I would ask them, what's it like where you live?
Henry, Gloucester, England
I will teach them how to play football and then say my name in English.
Ben, Feltham, England
Hi, what's your name? What's the colour of my pen? What is the opposite of on?
Kyle, Feltham, England
What's up? Don't invade Earth!
Felix, Falkirk, Scotland
Hello, I am a human and my name is Rosie. I wanted to see if aliens are real and if you are reading this then you are real. I want to ask a few questions. What do you do where you are? Would you ever want to come to a human country?
Rosie, Feltham, England
Dear aliens, hello! I am a human from planet Earth. Why are you sending messages to our scientists? Maybe you could visit earth one day (but only if you are friendly, and no bigger than a human, about 2m high) From Emily. If there was an alien in front of me right now I would say "AAAAAAHHH an alien!"
Emily, Feltham, England
I would say "Hi alien, do you have chocolate on your world?"
Grace, Hillingdon, England
How are you and how old are you? Promise not to be angry or try to take over the world! I hope the messages we humans sent you aren't troubling your world.
Adam, Feltham, England
I don't mean to scare you. I want to be your friend. How is it living in space and talking another language? Sorry if you don't understand. What's your favourite thing about space? Mine is the stars. They're beautiful. They just glisten in the sky and twinkle!
Bojana, Feltham, England
Hi, I come in peace.
Harry, Feltham, England
Hello, why are you green? In my world we have cars, helicopters and motorbikes but what do you have? Do you have homes? Do you sleep? Do you ever die? What food do you eat?
Chadli, Feltham, England
Hi, what language do you speak? How does your world work? Is there gravity in your world? Don't be scared of our world.
Elisha, Feltham, England