Updated 10 January 2003, 09.54
For the first Newsround Extra programme of 2003, Becky looked at whether life could exist outside Earth - and now we want to know what you think!
Do you believe there are already little green men living in outer space?
Or is it a load of rubbish made up by people with really good imaginations?
Or perhaps you agree with some scientists, and think there might be tiny living organisms floating about on other planets - aliens, but not as we know them?
Whatever your theories on life in outer space, let everyone know right now!
I think, out of the trillions of stars in our universe and hundreds of planets orbiting them, the chances of there being life elsewhere is extremely high. But our chances of finding them may be considerably lower. Some scientists say there must be water on land or below ground and oxygen in their atmosphere but I think it's more likely that they survive of a different gas such as nitrogen or hydrogen. Also they say conditions should be that of Earth's but they may be suited to a completely different temperature or pressure. But if other civilizations did need water and oxygen then Europa (one of Jupiter's moons) the huge ocean under the sheet of ice could be a perfect habitat. Also the phrase 'little green men' could be so wrong, they could look exactly like us.
Ben, 12, Kenfig Hill
You all are so stupid. For the person who spoke about the Milky Way, if your small brain could possibly comprehend how big the Milky Way is alone, youd understand that there has to be life in just this Galaxy. And as for spending money on other things besides space exploration, SCREW THAT, this world is so messed up and will be destroyed soon anyway so space exploration in a way is our ONLY thing we should be doing, it is where the future of this planet lies.
Chris, 16, Tampa
I think they do exist as I have seen a UFO but you have to see to believe truly in my view.
Michael, 14, Stroud
Believe that and you'll believe anything! i mean it's only now that there asking if Neil actually DID land on the moon, so come on!
When you consider the size of the universe I believe it's hard to imagine that we really are the only form of life around. I think there is definitely life on other planets, and perhaps in our own Solar System, it's just that it might take decades to find it.
Kathryn, 15, Dundalk
I think there is life on other planets, but people in this world shouldn't be spending ridiculous amounts of money on expeditions into space when the money could be going to help people in poverty in this world! What is the point in looking for life on other planets when we can't even get our own planet sorted out!!
Carmel, 15, Glossop
I don't believe in aliens but if somebody goes and brings one back then I would believe it.
Kacee, 11, Tebbets
Probably, it's really selfish to think that we're the only planet with living things. It's probably almost impossible for a planet to be able to support life, but ours can, and it's a BIG universe...
Cristina, 14, New York, USA
My dad and me saw a UFO on a road trip in Ohio. It was very bright and moved very fast. It was zigzagging in the sky for a long time until it shot off into space.
Chris, 14, Rochester
They are real. They are grey and skinny. Not too tall. They have big eyes and long fingers. There skin is like cardboard. They live in UFOs in our atmosphere but come from far off planets. They are our friends.
Anne, 13, Bedford
I definitely think aliens exist. I mean, out of all the planets and all the solar systems, how could only ONE planet have life on it? How self-centred is that? But, I don't think they look like little green men...I doubt they look like humans though!
Lauren, 13, USA
I think there probably is alien life in space somewhere, but not much and so few and far between that it's unlikely that we'll ever meet it.
Natalie, 15, Leicestershire
I think there is a chance that there is life on other planets. But I don't think they will be green and have millions of eyes and wobble like jelly. But there will a kind of creature on different planets.
Nadine, 10, Durham
I am VERY confident that aliens exist. We don't even know how big the universe is! There must be loads of other life forms out there. As for what they look like, I have no idea whatsoever!
Charlotte, 14, Wakefield
I hope there is!!! It would be so cool if there were educated beings just like us on another planet.
Rose, 12, Totton
Yes they do - I saw one the other day it was green with bulging eyes!
Nareen, 13, Bedford
I don't want the scientists to find aliens because they'll just cut them up to find out more about them !
Rochelle, 13, Newbridge
I think that even if there is life on another planet, we shouldn't be spending billions of pounds on finding out. There are more important things to spend the money on, like hospitals and the third world.
Hattie, 11, Ross-on-Wye
I think there could be other animal like creatures that have adapted to life on another planet as we have on ours. The universe is so vast that there must be other worlds similar to ours or different but with beings that can survive there.
Hermione, 15, Bucks
They are gorgeous and sexy! Oh no, that's Busted! I think that they are pink with blue dog ears! I don't know why I just do!
Laura, 13, Southampton
Jamie from Perth - We have found life on other planets. There is of life on Mars, but only small organisms. They are still living though!
Darren, 16, Carrickfergus
I don't believe in aliens. But I think that they will find different plants and traces of life around the universe.
Elycia, 11, Stevenage
I don't think there is life on any of the planets near Earth, like Mars, but somewhere out there, there might be. It's probably bacteria or something.
Katelyn, 13, London
I do not believe in aliens from another planet! I've seen ET but I don't believe in aliens at all.
Karen, 16, Wokingham
I can't see that with so many solar systems in so many galaxies that we can be the only planet with life, so I guess there must be some sort of other life out there. Obviously we won't have a clue what they look like because it would all depend on environment and certain things happening to what they evolved to be.
Isobel, 15, Kent
I think that there is life on another planet. What if they look like us?! That would be cool! I am not sure if there is such a thing as aliens but there is definitely something out there that we haven't found yet.
Hollie, 13, Aberdeen
It is naive to think we are the only living things in this huge universe, so yes I do believe in aliens. I have no idea what they look like. They might even look exactly like us! Who knows?
Jenny, 15, Derby
For all I know aliens could be really small and look like a butterfly. So really I don't know, but I'm sure they wouldn't look anything like the alien in ET.
I don't think there's alien life in the Milky Way but I think it's pretty arrogant of humans to think that in the whole universe we are the only intelligent life form.
Alexandra, 12, Horley
I've seen ET the movie, and I don't think that's what aliens are like. But I think it won't be long before we find out that life of some kind exists on other plants. But I have no idea what it will look like.
Jamie, 11, Perth
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.