0:00:02 > 0:00:07Last October, astronomers made a spectacular discovery.
0:00:07 > 0:00:08For the very first time,
0:00:08 > 0:00:13they spotted an object visiting our solar system from outer space.
0:00:15 > 0:00:18It set off a hurricane of press speculation.
0:00:23 > 0:00:26Tonight, we have new, exclusive revelations
0:00:26 > 0:00:30and reveal the complete story of this mysterious visitor,
0:00:30 > 0:00:34which now goes by a suitably exotic name -
0:00:34 > 0:00:35'Oumuamua.
0:01:09 > 0:01:12To tell this detective story, I've come here to Belfast,
0:01:12 > 0:01:15which has become the centre of research into
0:01:15 > 0:01:16this cosmic visitor -
0:01:16 > 0:01:20an object called 'Oumuamua.
0:01:20 > 0:01:23When we first saw it, all we knew was that it was small
0:01:23 > 0:01:27and moving fast. The first object from deep space ever to be seen
0:01:27 > 0:01:30passing through our solar system.
0:01:30 > 0:01:33And its sudden appearance raised a whole host of questions.
0:01:34 > 0:01:38What did it look like? How had it formed?
0:01:38 > 0:01:42What was it made of? And where had it come from?
0:01:42 > 0:01:44To answer these questions,
0:01:44 > 0:01:48I'm going to piece together all the clues that scientists were able
0:01:48 > 0:01:52to extract from the small amount of data that they gathered as 'Oumuamua
0:01:52 > 0:01:55flashed through the solar system.
0:01:55 > 0:01:59This forensic analysis, including new, exclusive revelations,
0:01:59 > 0:02:02will give us the most comprehensive picture yet
0:02:02 > 0:02:04of this extraordinary object.
0:02:07 > 0:02:11Our story starts in Hawaii in mid-October last year,
0:02:11 > 0:02:14when one of the biggest telescopes in the world
0:02:14 > 0:02:15spotted something unusual.
0:02:19 > 0:02:20Now, this is the first picture taken
0:02:20 > 0:02:24of 'Oumuamua from the telescope in Hawaii.
0:02:24 > 0:02:26Looking at it, it's quite hard to spot
0:02:26 > 0:02:29but it's actually this splodge here.
0:02:29 > 0:02:32Now, you can tell it's moving really fast
0:02:32 > 0:02:34because the stars appear as points,
0:02:34 > 0:02:36whereas this is a blur across the screen.
0:02:42 > 0:02:46I called Karen Meech in Hawaii, who led the team that night,
0:02:46 > 0:02:48to find out how the discovery was made.
0:02:50 > 0:02:52Hi, Karen. Nice to meet you and thank you for waking up so early.
0:02:52 > 0:02:54- No problem.- Now, can you take us
0:02:54 > 0:02:57through the night of the first observation?
0:02:57 > 0:03:01Well, this was discovered by the Pan-STARRS telescope in Hawaii,
0:03:01 > 0:03:04which is conducting a Nasa-funded search
0:03:04 > 0:03:06for near-Earth objects.
0:03:06 > 0:03:10And this particular night, on the 19th of October,
0:03:10 > 0:03:12one of the objects that was flagged
0:03:12 > 0:03:17had a very long streak, which meant it was moving quite fast.
0:03:17 > 0:03:20So, what had you effectively discovered by then?
0:03:20 > 0:03:22Well, at that point, people weren't sure.
0:03:22 > 0:03:27But as soon as some follow-up observations came in,
0:03:27 > 0:03:33one of the groups at the European Space Agency ground station reported
0:03:33 > 0:03:35that the orbit looked interesting.
0:03:35 > 0:03:39Namely, they said its shape didn't look circular.
0:03:39 > 0:03:43And it wasn't until a few more nights of data came in
0:03:43 > 0:03:46that we decided that this was definitively
0:03:46 > 0:03:48something from outside the solar system.
0:03:48 > 0:03:52How did you feel when you found out that it was an extrasolar object
0:03:52 > 0:03:54coming from another solar system?
0:03:54 > 0:03:58I actually sat there for a while just thinking about
0:03:58 > 0:04:01what it meant and getting more and more excited
0:04:01 > 0:04:03that this really is the first time we have
0:04:03 > 0:04:07something so close that's delivered from outside.
0:04:07 > 0:04:11The frustrating thing was that it was moving so fast.
0:04:11 > 0:04:12We only had a little over a week
0:04:12 > 0:04:15during which time it was bright enough to
0:04:15 > 0:04:17actually do the experiments we'd like to do.
0:04:17 > 0:04:20So, what that really meant was a team of people
0:04:20 > 0:04:24were working around the clock and I ended up sleeping in the office
0:04:24 > 0:04:27for most of the week, because we were putting in 18-hour workdays.
0:04:27 > 0:04:29How do you go about naming these objects?
0:04:29 > 0:04:32We thought it might be nice to have a Hawaiian name.
0:04:32 > 0:04:36And so the director suggested that we talk to
0:04:36 > 0:04:40a Hawaiian navigator and a Hawaiian linguistics expert
0:04:40 > 0:04:44on the Big Island. And they suggested a very nice name to us.
0:04:44 > 0:04:50It was 'Oumuamua, where the O means "to reach out for",
0:04:50 > 0:04:52and "mua" means "first" or "in advance of",
0:04:52 > 0:04:57and by duplicating that piece, it gives it emphasis in Hawaiian.
0:04:57 > 0:04:59So, the intent of their definition was that
0:04:59 > 0:05:02this is a scout or distant messenger
0:05:02 > 0:05:05sent out from our beginnings to reach out to us
0:05:05 > 0:05:06or build connections with us,
0:05:06 > 0:05:08so we thought it was a very appropriate name.
0:05:08 > 0:05:10Thank you so much, Karen.
0:05:10 > 0:05:14It's a fascinating story and I'm looking forward to finding out more.
0:05:14 > 0:05:15Well, thank you.
0:05:18 > 0:05:21Karen's discovery caught the imagination of scientists
0:05:21 > 0:05:22around the world.
0:05:25 > 0:05:27First indications were that 'Oumuamua
0:05:27 > 0:05:30was just a few hundred metres across
0:05:30 > 0:05:33and was travelling at over 50km per second.
0:05:36 > 0:05:39But the big story was about its origins.
0:05:41 > 0:05:45Within days, scientists had gathered enough data to start working out
0:05:45 > 0:05:48the trajectory of 'Oumuamua.
0:05:48 > 0:05:51Now, initially they assumed that it was an elliptical orbit.
0:05:52 > 0:05:56But just days later, they realised it wasn't an orbit at all.
0:05:56 > 0:05:58It was actually open.
0:05:58 > 0:06:01Now, this flagged up all sorts of questions,
0:06:01 > 0:06:04because it meant that 'Oumuamua didn't originate
0:06:04 > 0:06:05from within our solar system.
0:06:05 > 0:06:07More importantly,
0:06:07 > 0:06:10they'd only spotted it as it made its journey outward
0:06:10 > 0:06:13from the solar system. That meant they had a limited time
0:06:13 > 0:06:17to gather more data to find out what it was like, how it was made,
0:06:17 > 0:06:18and where it had come from.
0:06:23 > 0:06:25By late October, astronomers in Belfast
0:06:25 > 0:06:28and around the world were getting excited.
0:06:28 > 0:06:31Michele Bannister's team were among the first to take on the quest
0:06:31 > 0:06:34to understand 'Oumuamua.
0:06:35 > 0:06:37They focused on what it looked like,
0:06:37 > 0:06:40what shape it was, and - crucially - what colour.
0:06:42 > 0:06:44So, you did what astronomers have always done,
0:06:44 > 0:06:48which is ask simple questions like, "What colour is it?"
0:06:48 > 0:06:49That can often tell us a lot.
0:06:49 > 0:06:51Yeah. So, we're seeing this object
0:06:51 > 0:06:53entirely with reflected sunlight.
0:06:53 > 0:06:55And so the colour that you get
0:06:55 > 0:06:58of the reflected surface tells you about
0:06:58 > 0:07:00potentially what the composition is.
0:07:00 > 0:07:02And, so, what colour is it?
0:07:02 > 0:07:05It's a touch redder than sunlight, but kind of pinky.
0:07:05 > 0:07:08However, you wouldn't see that if you were to look at 'Oumuamua
0:07:08 > 0:07:11with your naked eye, rather than with one of the world's biggest
0:07:11 > 0:07:15telescopes, because when it reflects the sun's light,
0:07:15 > 0:07:18it's reflecting it back at almost the same colour as the sun.
0:07:18 > 0:07:21Just a bit redder in the infrared part of the spectrum.
0:07:25 > 0:07:27This colour, a hint of pink or red
0:07:27 > 0:07:30especially noticeable in the infrared,
0:07:30 > 0:07:33is reminiscent of some objects in our own solar system.
0:07:36 > 0:07:41It could actually be a little cousin of one of the objects that you see
0:07:41 > 0:07:44in the populations known as Jupiter Trojans,
0:07:44 > 0:07:45which orbit out near Jupiter.
0:07:45 > 0:07:48Another thing your observations showed was that the brightness of
0:07:48 > 0:07:50the object was changing over time.
0:07:50 > 0:07:53Yes, we observed for about two hours.
0:07:53 > 0:07:55So, if I show you here...
0:07:55 > 0:07:57So, this gives you some idea of how
0:07:57 > 0:07:58the brightness that we measured
0:07:58 > 0:08:00- changed over time.- You've got this
0:08:00 > 0:08:03really quite dramatic dip here. It faces quite dramatically,
0:08:03 > 0:08:05- and then recovers. - It changes in brightness
0:08:05 > 0:08:07over a remarkable amount of contrast
0:08:07 > 0:08:10and we weren't expecting that. That was great.
0:08:10 > 0:08:12What do we think causes that variation?
0:08:12 > 0:08:14Probably the shape of the object.
0:08:14 > 0:08:18So, I have a way of showing you what effect shape is going to have on
0:08:18 > 0:08:20- the brightness of an object over time.- OK.
0:08:20 > 0:08:22So, here I have a sun...
0:08:22 > 0:08:26- OK.- Here I have a turntable that is rotating an object over time.
0:08:26 > 0:08:29- OK.- So, the camera is watching this object and it can't see the shape of
0:08:29 > 0:08:32the object directly. It's just going to see its brightness.
0:08:32 > 0:08:37On the screen here, you see what the camera is measuring of how it sees
0:08:37 > 0:08:41this little object changing in brightness over time as it rotates.
0:08:41 > 0:08:43Now, the sphere - you can see you don't get much change
0:08:43 > 0:08:46- in brightness at all.- No.
0:08:46 > 0:08:49Let's try this with something a bit stranger in shape.
0:08:49 > 0:08:51OK, I'll remove the sphere. There we go.
0:08:51 > 0:08:55Instead, put on this delightful potato asteroid here.
0:08:55 > 0:08:59- Fine.- And you can see what the camera is seeing
0:08:59 > 0:09:02as this point of light changes in brightness
0:09:02 > 0:09:06as it turns, is when the short end is pointing towards the camera...
0:09:06 > 0:09:09- Like it is now.- ..you have minimum surface area being reflected,
0:09:09 > 0:09:12the light, so it's dimmest. And when it turns round
0:09:12 > 0:09:17and the whole side of this object is being illuminated,
0:09:17 > 0:09:20it's the brightest to the camera,
0:09:20 > 0:09:21and so you see this brightness peak.
0:09:23 > 0:09:26And what do you find? What shape is 'Oumuamua?
0:09:26 > 0:09:31It's actually got to be even more elongated than this little potato.
0:09:31 > 0:09:35This is 3:1. 'Oumuamua has to be at least 5:1,
0:09:35 > 0:09:37maybe even a bit longer.
0:09:37 > 0:09:39But this is the thing, when I saw this result
0:09:39 > 0:09:42from all this hard work of astronomers
0:09:42 > 0:09:45scrambling to telescopes, it seems to me very unlikely
0:09:45 > 0:09:50that the first interstellar visitor would be this unusual.
0:09:50 > 0:09:52Is that something that disturbs you,
0:09:52 > 0:09:55or does this make sense if you've been thinking about these things?
0:09:55 > 0:09:57The shape is a bit unusual,
0:09:57 > 0:10:01but the colour is so much like what we see in our own solar system.
0:10:01 > 0:10:03There's a kinship there. It tells you that something that formed
0:10:03 > 0:10:06around a different star and something that formed
0:10:06 > 0:10:09around our own star have a lot of similarity in their surface.
0:10:09 > 0:10:11It's a very deep thought, that.
0:10:11 > 0:10:14It's sort of a poetic... It's scientific, but it's poetic as well,
0:10:14 > 0:10:15that there is this relationship
0:10:15 > 0:10:17to something that came from so far away.
0:10:17 > 0:10:21Yeah, we're finally getting to touch something that's from
0:10:21 > 0:10:24another solar system that's larger than a grain of dust.
0:10:28 > 0:10:30Within days of being spotted,
0:10:30 > 0:10:34detailed information about 'Oumuamua was coming in.
0:10:34 > 0:10:37From Michele's light analysis, a shape was proposed.
0:10:37 > 0:10:41It was thought to be an elongated cigar shape,
0:10:41 > 0:10:43100 to 400 metres in length.
0:10:43 > 0:10:46The ratio of length to width was thought to lie
0:10:46 > 0:10:48between 10:1 and 5:1.
0:10:50 > 0:10:54And although it was dark, it seemed to have a touch of pink or red.
0:10:58 > 0:10:59By the end of November,
0:10:59 > 0:11:04the strange shape and exotic nature of 'Oumuamua had led to some
0:11:04 > 0:11:06extraordinary speculations.
0:11:13 > 0:11:15Was 'Oumuamua an alien artefact?
0:11:25 > 0:11:28It wasn't an entirely stupid question.
0:11:28 > 0:11:30'Oumuamua was so strange
0:11:30 > 0:11:33that at this stage almost anything seemed possible.
0:11:33 > 0:11:38So I met astrophysicist and expert in the search for extraterrestrials
0:11:38 > 0:11:43Duncan Forgan, to find out how scientists deal with the question of
0:11:43 > 0:11:46whether an object is natural or alien.
0:11:46 > 0:11:50So, Duncan, all this very interesting data was coming through,
0:11:50 > 0:11:52what was the press's response to it?
0:11:52 > 0:11:54It was a little bit frenzied, to be honest.
0:11:54 > 0:11:57There were a lot of stories about this idea that maybe this
0:11:57 > 0:11:59weird interstellar visitor was, in fact,
0:11:59 > 0:12:01an alien spacecraft coming to visit the Earth.
0:12:01 > 0:12:05But, unfortunately, a lot of that stuff was very overbaked.
0:12:05 > 0:12:08So, how should scientists treat these stories?
0:12:08 > 0:12:10I think it's important to make sure that when you're thinking about,
0:12:10 > 0:12:14"What is this new, interesting, weird thing?"
0:12:14 > 0:12:17you make your list of natural explanations,
0:12:17 > 0:12:20- and then right at the very bottom you put the aliens explanation.- OK.
0:12:20 > 0:12:23And you wait until you've exhausted all the natural explanations.
0:12:23 > 0:12:27And then, when nothing else is left, Sherlock Holmes-style,
0:12:27 > 0:12:29you come back to the aliens explanation.
0:12:29 > 0:12:31So, one of the things that we did was to basically check
0:12:31 > 0:12:33if 'Oumuamua was a transmitter.
0:12:33 > 0:12:36So, they wanted to see if it was emitting radio waves
0:12:36 > 0:12:38in the way that we'd expect a radio transmitter
0:12:38 > 0:12:40built by an intelligent being to work,
0:12:40 > 0:12:42so they pointed their radio telescopes at 'Oumuamua
0:12:42 > 0:12:44and checked and found nothing.
0:12:44 > 0:12:48So, what would you have done if it was found out that 'Oumuamua
0:12:48 > 0:12:50was an alien artefact?
0:12:50 > 0:12:53There are a list of protocols that people who are doing the search
0:12:53 > 0:12:56for intelligent life are supposed to follow -
0:12:56 > 0:12:59what they call a post-detection protocol, so what do you do next?
0:12:59 > 0:13:02And so one of the things you need to do is A - check your answer,
0:13:02 > 0:13:05- because if you get this wrong it could be very embarrassing.- Yes.
0:13:05 > 0:13:08So, ask your colleagues to use a different instrument and try and do
0:13:08 > 0:13:11the same experiment and if it comes out to be the same answer
0:13:11 > 0:13:14then, OK, you've got something there. And then get more and more
0:13:14 > 0:13:17people to check and make sure that your hypothesis has been validated.
0:13:17 > 0:13:19And then you go to United Nations and tell the Secretary General,
0:13:19 > 0:13:22"By the way, there's alien life and it's coming towards us."
0:13:22 > 0:13:24- An interesting e-mail!- Yeah.
0:13:24 > 0:13:26And then you're supposed to tell the public at large.
0:13:26 > 0:13:29- Well, thank you so much. It's been fascinating.- Thank you.
0:13:42 > 0:13:47In mid-December, the mysteries about 'Oumuamua were still mounting,
0:13:47 > 0:13:51and scientists were beginning to wonder just where it had come from.
0:13:53 > 0:13:55Michele Bannister picks up the story.
0:13:57 > 0:14:01So, this brings me to the next question I wanted to ask, which is -
0:14:01 > 0:14:04do we know where this asteroid, this body, came from?
0:14:04 > 0:14:09It seems to me you've seen it coming in, so can we trace it back?
0:14:09 > 0:14:11That will be a work in progress.
0:14:11 > 0:14:13What we can do is say the arc that it took as it came into
0:14:13 > 0:14:18the solar system, if we extend that back and back and back
0:14:18 > 0:14:20for 100 million years...
0:14:20 > 0:14:24You know, that's the better part of halfway round the galaxy
0:14:24 > 0:14:26- as the sun's travelling.- OK, so we've travelled a long way,
0:14:26 > 0:14:29- this thing's been moving, it's complicated.- Yeah.
0:14:29 > 0:14:32You have to run the galaxy backwards in time and say,
0:14:32 > 0:14:36"Where were all the stars millions and millions of years ago?"
0:14:36 > 0:14:39And then say, "Was 'Oumuamua close to one of these stars?"
0:14:39 > 0:14:42And if it was, that's its last port of call.
0:14:42 > 0:14:45Now, that's not the same thing as saying that's where it's from.
0:14:45 > 0:14:49- No.- Because the next star system that 'Oumuamua goes through,
0:14:49 > 0:14:50it'll look like it came from us.
0:14:50 > 0:14:52That's true. People will trace...
0:14:52 > 0:14:55Aliens will trace it back and think it came from here.
0:14:55 > 0:14:59But people have tried to match this trajectory,
0:14:59 > 0:15:01to do this difficult calculation - how have they got on?
0:15:01 > 0:15:04You can see it comes not close-close,
0:15:04 > 0:15:08but perhaps a little bit close to some stars.
0:15:08 > 0:15:12There's about 15 stars that are currently potential candidates that
0:15:12 > 0:15:14it could've come near in that time.
0:15:14 > 0:15:16But everything starts getting a little fuzzy, because we don't
0:15:16 > 0:15:19actually know the positions of these stars particularly well.
0:15:19 > 0:15:22About five of them are in a group of stars
0:15:22 > 0:15:26loosely called the Local Association.
0:15:26 > 0:15:28It's an amazing thought that it might be bouncing around
0:15:28 > 0:15:31and, of course, it may encounter other stars in the future.
0:15:31 > 0:15:32It has a long journey to go.
0:15:32 > 0:15:35- Michele, thank you very much. - Thank you, Chris.
0:15:37 > 0:15:41So tracking 'Oumuamua's orbit back through time and space has suggested
0:15:41 > 0:15:45that it might come from a group of stars that astronomers call
0:15:45 > 0:15:47the Local Association.
0:15:48 > 0:15:51You might think that the Local Association would be a nice, neat
0:15:51 > 0:15:55little cluster of stars in the night sky, but it isn't that simple.
0:15:57 > 0:15:59Although they all formed around the same place
0:15:59 > 0:16:01and at around the same time,
0:16:01 > 0:16:05just 100 million years ago, they have since spread out.
0:16:11 > 0:16:14Pete Lawrence explores this Local Association,
0:16:14 > 0:16:18starting by looking towards the southern part of the sky.
0:16:21 > 0:16:22The Local Association
0:16:22 > 0:16:25is roughly in this direction here.
0:16:25 > 0:16:27Most of the stars in it are too dim to be seen
0:16:27 > 0:16:30with the naked eye, but it does include one of my favourite
0:16:30 > 0:16:32open clusters, the Pleiades.
0:16:34 > 0:16:37The Pleiades are some of our closest neighbours,
0:16:37 > 0:16:40at a distance of 440 light years.
0:16:40 > 0:16:43They're very distinctive, like a miniature Plough.
0:16:44 > 0:16:48To locate them, find Orion in the southern sky
0:16:48 > 0:16:51and follow the line of the belt up and to the right,
0:16:51 > 0:16:54past Taurus and its distinctive V,
0:16:54 > 0:16:56and then continue the line.
0:16:56 > 0:16:58You should see a little huddle
0:16:58 > 0:17:00of beautiful blue-white stars.
0:17:02 > 0:17:05These really are one of the highlights of the winter night sky,
0:17:05 > 0:17:08looking like rare jewels on black velvet.
0:17:08 > 0:17:11But binoculars or a telescope will show even more.
0:17:12 > 0:17:16And photography reveals an exquisite blue nebula,
0:17:16 > 0:17:20visible because of light reflecting off of a cloud of dust
0:17:20 > 0:17:22that the stars are moving through.
0:17:24 > 0:17:28Associations like this are often hundreds of light years across.
0:17:28 > 0:17:32For instance, there's another star in the association, which you can
0:17:32 > 0:17:34find by heading southeast from the Pleiades
0:17:34 > 0:17:37so that you're on the other side of Orion, the Hunter.
0:17:37 > 0:17:38So a fair distance away.
0:17:38 > 0:17:42Here you're in the constellation of Monoceros, the unicorn.
0:17:42 > 0:17:45And there's a faint star there
0:17:45 > 0:17:49which is a candidate for the origin of 'Oumuamua.
0:17:51 > 0:17:54The star is called Ross 614.
0:17:54 > 0:17:57You'll need a telescope to see it,
0:17:57 > 0:18:02but to find it go back to Orion and head south and east.
0:18:02 > 0:18:04Monoceros, or the unicorn,
0:18:04 > 0:18:06is a group of fairly dim stars
0:18:06 > 0:18:09between Canis Major and Canis Minor.
0:18:09 > 0:18:11And Ross 614 is about
0:18:11 > 0:18:14halfway along his front leg.
0:18:16 > 0:18:18And it's in this group...
0:18:18 > 0:18:20Oh, there it is!
0:18:20 > 0:18:23It's just 13 light years away and is a component
0:18:23 > 0:18:25in a red-dwarf binary system.
0:18:25 > 0:18:29And it's fascinating and really exciting to think that may be
0:18:29 > 0:18:32where 'Oumuamua came from.
0:18:36 > 0:18:41By now, scientists had worked out quite a bit about 'Oumuamua.
0:18:41 > 0:18:44They knew its rough size, speed and colour.
0:18:44 > 0:18:46And if it did come from the Local Association,
0:18:46 > 0:18:49they knew its age, too -
0:18:49 > 0:18:51100 million years,
0:18:51 > 0:18:53when these stars were formed.
0:18:54 > 0:18:56But two big mysteries remained.
0:18:56 > 0:18:59What was it made of and how was it formed?
0:19:03 > 0:19:06Back in Belfast, Chris met up with Alan Fitzsimmons,
0:19:06 > 0:19:11who started to investigate 'Oumuamua's composition.
0:19:11 > 0:19:16His team believed it was icy, like most small distant objects.
0:19:16 > 0:19:20But all the images they collected told a different story.
0:19:20 > 0:19:24Because, if it was icy, why didn't it have a tail?
0:19:27 > 0:19:30And so you got those images back and you were expecting to see what?
0:19:30 > 0:19:32A comet with a nice tail, I guess.
0:19:32 > 0:19:35That's right. This object passed pretty close to the sun,
0:19:35 > 0:19:37and so the ices there should have been heated
0:19:37 > 0:19:39and we should have seen that material expanding
0:19:39 > 0:19:42away to form the atmosphere of the comet and the tail,
0:19:42 > 0:19:43but there was nothing like that.
0:19:43 > 0:19:46It looked like an asteroid, and so we were thinking,
0:19:46 > 0:19:48"What is this thing?"
0:19:48 > 0:19:49What did you do next?
0:19:49 > 0:19:52The important thing then was to figure out how this object was
0:19:52 > 0:19:54reflecting light because that could give us to a clue
0:19:54 > 0:19:56to what it was made of. To do that,
0:19:56 > 0:19:58we needed to get spectroscopy of the object.
0:19:58 > 0:20:00So, what did the spectrum show?
0:20:00 > 0:20:02Well, we saw the signature of carbon.
0:20:02 > 0:20:04- Carbon?- Yeah.
0:20:04 > 0:20:06Now, when we think of an icy comet,
0:20:06 > 0:20:09we think of something that's mostly made of water ice,
0:20:09 > 0:20:13although there may be some carbon monoxide and carbon dioxide.
0:20:13 > 0:20:16This is an object that could have been out there between the stars for
0:20:16 > 0:20:18millions or billions of years.
0:20:18 > 0:20:22And so it's been sitting out there and during that time
0:20:22 > 0:20:25it's been affected by the cosmic rays,
0:20:25 > 0:20:28high-energy particles that fill our galaxy.
0:20:28 > 0:20:32OK, so it's the cosmic rays that might have changed the surface.
0:20:32 > 0:20:35- What would they have done to it? - They take those ices on the surface,
0:20:35 > 0:20:37and in particular they take the carbon,
0:20:37 > 0:20:40and the carbon rearranges itself
0:20:40 > 0:20:43to form new molecules and new compounds.
0:20:43 > 0:20:46And so what does that look like? How can we see what's happening?
0:20:46 > 0:20:48I can explain using this demo, now...
0:20:48 > 0:20:53- OK.- Basically a meringue - egg whites and sugar - OK?
0:20:53 > 0:20:56And we can add some energy. Now, we're not going to use cosmic rays.
0:20:56 > 0:20:59We're going to use a little blowtorch here.
0:20:59 > 0:21:02- OK. Well, safety first. - Safety first indeed.
0:21:02 > 0:21:05I do this every time I cook, you know. Very sensible. OK.
0:21:07 > 0:21:09- There we go.- And now,
0:21:09 > 0:21:12if we add energy to that we'll see a chemical transformation
0:21:12 > 0:21:14to a different substance.
0:21:14 > 0:21:17It's a very different material on the surface,
0:21:17 > 0:21:19with the meringue intact inside.
0:21:19 > 0:21:22Now... This is great cooking,
0:21:22 > 0:21:25but what's this got to do with an interstellar asteroid
0:21:25 > 0:21:29- or interstellar comet?- Well, instead of egg whites, of course,
0:21:29 > 0:21:32and sugar, we have ice, we believe, that we start off with.
0:21:32 > 0:21:34And instead of a blowtorch,
0:21:34 > 0:21:37we have energy deposited on the surface by cosmic rays.
0:21:37 > 0:21:39But only on the surface?
0:21:39 > 0:21:42That's right. Now, over about 100 million years,
0:21:42 > 0:21:48this chemical transformation can go down about half a metre or so.
0:21:48 > 0:21:52Within that depth, we could still have ice there.
0:21:52 > 0:21:56And the important thing is this not only changes the surface properties
0:21:56 > 0:22:01and how it reflects light, this new crust of carbon-based material
0:22:01 > 0:22:04also insulates the interior.
0:22:04 > 0:22:07So it locks in, perhaps, the ice that's still there.
0:22:07 > 0:22:11That's right, and when we do the calculations we find that
0:22:11 > 0:22:14even though 'Oumuamua passed within the orbit of Mercury,
0:22:14 > 0:22:17passed very close to the sun,
0:22:17 > 0:22:20that heat from the sun could not have penetrated
0:22:20 > 0:22:22within more than half a metre.
0:22:22 > 0:22:24So the ice would have remained locked up
0:22:24 > 0:22:27and that explains why we didn't see a comet,
0:22:27 > 0:22:31we saw something that looked initially like an asteroid.
0:22:31 > 0:22:33We'll look forward to hearing about whatever comes next.
0:22:33 > 0:22:36- Alan, thank you very much. - Thank you.
0:22:47 > 0:22:50By Christmas, scientists had a pretty good understanding
0:22:50 > 0:22:55what 'Oumuamua was made of. But then came a new and exciting discovery -
0:22:55 > 0:22:58revealed tonight for the very first time.
0:23:03 > 0:23:07A powerful new theory started to emerge,
0:23:07 > 0:23:13based on a detailed analysis of the light reflected off 'Oumuamua.
0:23:13 > 0:23:19It suggested not just how it was formed, but also where it came from.
0:23:20 > 0:23:22To find out more,
0:23:22 > 0:23:26Chris met lead scientist on this new research Wes Fraser.
0:23:28 > 0:23:30So, Wes, taking a close look at this thing,
0:23:30 > 0:23:32it turns out to be even more complicated than we thought.
0:23:32 > 0:23:36- What's going on?- Well, I was weirded out by the fact
0:23:36 > 0:23:40that no-one publishing all these papers coming out of 'Oumuamua
0:23:40 > 0:23:43could actually determine how quickly it was rotating.
0:23:43 > 0:23:46And so one morning, one Friday morning, I just thought,
0:23:46 > 0:23:48"I'm just going to pull all of this together and see what I can see.
0:23:48 > 0:23:51"Now that we've got many days' worth of observations,
0:23:51 > 0:23:55"surely we can pull all of this data together and just figure out how quickly this thing is spinning."
0:23:58 > 0:24:01Wes's new investigation compares the light we might expect
0:24:01 > 0:24:04from a spinning object, shown with the dotted line,
0:24:04 > 0:24:07with the data that Wes actually gathered.
0:24:08 > 0:24:10So, if you look at the plot here,
0:24:10 > 0:24:12it works in some places,
0:24:12 > 0:24:14but it completely fails in others -
0:24:14 > 0:24:15where the curve is low,
0:24:15 > 0:24:17the data are high.
0:24:17 > 0:24:19- Yeah, yeah. Look, down here in day five - it's way off.- Yes, exactly.
0:24:19 > 0:24:22Or even in the first couple of days, there's something odd going on.
0:24:22 > 0:24:25It was exactly the comparison between night two and night five
0:24:25 > 0:24:28that really... "OK, there's something weird going on here."
0:24:28 > 0:24:30- OK.- And so we started to look at it a little bit,
0:24:30 > 0:24:33and it was very clear that, in fact, this thing is tumbling.
0:24:33 > 0:24:34So, what do you mean by "tumbling"?
0:24:34 > 0:24:37Tumbling is an unusual state of rotation.
0:24:37 > 0:24:40We can demonstrate this with a simple ping-pong paddle.
0:24:40 > 0:24:42So, when we throw it like this...
0:24:47 > 0:24:50..just spins on a single axis and it remains that way.
0:24:50 > 0:24:52But when we throw it like this...
0:24:55 > 0:24:57..it immediately enters tumbling.
0:24:57 > 0:24:58It spins like this at the start,
0:24:58 > 0:25:01but then quickly starts to wobble around chaotically.
0:25:01 > 0:25:03And that's what we call tumbling.
0:25:03 > 0:25:05This thing's been travelling in space for a long time.
0:25:05 > 0:25:07How does it end up tumbling like this?
0:25:07 > 0:25:10We think it was due to a collision.
0:25:10 > 0:25:13And so at some early stage of its life,
0:25:13 > 0:25:16it was just spinning normally like everything else
0:25:16 > 0:25:18and then it suffered a collision.
0:25:20 > 0:25:23That would impart enough energy on one particular spot
0:25:23 > 0:25:26in such a way as to then be confused in how it spins.
0:25:26 > 0:25:29And so where would that have happened? Out in empty space?
0:25:29 > 0:25:33No, so we can pretty safely assume that the collision that caused this
0:25:33 > 0:25:37thing to tumble was in its original stellar system,
0:25:37 > 0:25:40before it got kicked out.
0:25:40 > 0:25:42So this thing's carrying information
0:25:42 > 0:25:46- about the early days of a different solar system?- In a way, yeah.
0:25:46 > 0:25:50It's hard to know if it was during planet formation
0:25:50 > 0:25:52or after the planet formation process.
0:25:52 > 0:25:54Certainly more collisions happen while planets
0:25:54 > 0:25:57are growing than afterwards, so that's a very good guess.
0:26:02 > 0:26:06It now seems that Wes's result may tell us something profound.
0:26:06 > 0:26:11'Oumuamua could be a relic from the formation of another solar system.
0:26:13 > 0:26:16There is a chance that this tumbling occurred while planets were forming,
0:26:16 > 0:26:20and so this is actually a moderately violent process.
0:26:20 > 0:26:23So you can produce, you know, rocks and boulders and pebbles this way,
0:26:23 > 0:26:26but eventually you do produce the planets in the process.
0:26:26 > 0:26:31At that point, those collisions become violent and very destructive.
0:26:31 > 0:26:34This may very well be where 'Oumuamua's shape has come from.
0:26:34 > 0:26:37It's most likely where its tumbling has come from as well.
0:26:37 > 0:26:40And we do know that objects are kicked out of our solar system,
0:26:40 > 0:26:43as well - they have been and continue to do so.
0:26:43 > 0:26:47So, while this is a bit of space that has, you know,
0:26:47 > 0:26:50come its way to us, we are of course sending bits of ourselves naturally
0:26:50 > 0:26:53to other places as well in a similar way.
0:26:53 > 0:26:55You make it sound like the galaxy's full of these things.
0:26:55 > 0:26:58Must be. Very, very much so.
0:26:58 > 0:27:01- Yes.- So, how come this is the first one we've seen?
0:27:01 > 0:27:03How many more are there that we're missing?
0:27:03 > 0:27:04Our best guess at the moment -
0:27:04 > 0:27:06and this is pretty uncertain cos we've only ever seen one -
0:27:06 > 0:27:10but our best guess is, at least within our own solar system,
0:27:10 > 0:27:12there are about 10,000 of these currently passing
0:27:12 > 0:27:16- within the orbit of Neptune. - There are 10,000 of these...
0:27:16 > 0:27:18- That's right.- ..going through the solar system today?
0:27:18 > 0:27:21- Today.- Not this year, not... - Yep.- So, why don't you see them?
0:27:21 > 0:27:25For every one of those that we see, there's 10 or 100 that we miss.
0:27:25 > 0:27:27And that just because of the fact that they're moving.
0:27:27 > 0:27:31And so it was a fantastic job of the discoverers to find this thing.
0:27:31 > 0:27:34- It's a fantastic discovery.- Well, lots more to look forward to...
0:27:34 > 0:27:36- Yes, indeed.- ..and it will be intriguing to find out
0:27:36 > 0:27:39- whether this one is particularly unusual.- That's right.
0:27:39 > 0:27:40- Wes, thank you very much. - Thank you.
0:27:46 > 0:27:48The discovery of 'Oumuamua
0:27:48 > 0:27:52has been one of the great scientific stories of the last 12 months.
0:27:52 > 0:27:56This is our first deep-space object.
0:27:56 > 0:28:00And this is now the most complete picture we have of 'Oumuamua.
0:28:07 > 0:28:10It's now suggested that 'Oumuamua's origins
0:28:10 > 0:28:13lay in the chaos of planetary formation...
0:28:17 > 0:28:19..around a distant star...
0:28:21 > 0:28:24..perhaps 100 million years ago.
0:28:27 > 0:28:29That's it from Belfast for this month
0:28:29 > 0:28:32and we're taking a break next month, but we'll be back in April.
0:28:32 > 0:28:35In the meantime, don't forget to check out our website
0:28:35 > 0:28:39for Pete's star guide and for our special weekly weather forecast.
0:28:39 > 0:28:44And, of course, get outside and get looking up. Goodnight.