Narrator: We have a mysteriousnew kid on the block. Astronomers call it Oumuamua. Which in Hawaiian, roughly translates to “first time visitor from far away.” Oumuamua is the first interstellar object ever detected in our solar system.
Astronomers discovered it in 2017 with the Pan-STARRS1 telescope. And like all grand discoveries, it has raised morequestions than it answers. Where did it come from? What’s it made of? And yes, even the ultimatequery, is it aliens? That’s what two Harvardastrophysicists posed in a recent paper, suggesting that Oumuamuacould be some type of alien spacecraft.
And when we spoke with one of them, the idea didn’t sound asfar-fetched as you might think. Loeb: I prefer to adopt themaxim of Sherlock Holmes that if you rule out the impossible, whatever remains, as improbable as it is, must be the truth. Narrator: Now a good rule of thumb is that aliens are alwaysthe least likely answer. But here’s the thing, themore reasonable explanation right now isn’t panning out.
Most astronomers think that Oumuamua is probably a stray cometfrom another stellar system. The only problem is that itdoesn’t look like any comet we’ve ever seen, because it appears tolack that iconic tail. Loeb: There was ananomaly seen in the data. And it cannot be explained by the most conventional explanation, which in this case isa cometary outgassing. And so we propose analternative interpretation which is the only one I can think of.
Narrator: But it seemsextreme to assume aliens just because Oumuamua doesn’tlook like a comet, right? Not when the Harvard scientists accounted for another peculiarity. As Oumuamua traveledthrough our solar system, it didn’t follow the normalpath of a typical comet under the sun’s gravity. Rather, it slightly shifted off course, which couldn’t beexplained by gravity alone. Something else, some unknownforce was also at play, manipulating the object’s behavior.
Loeb: I cannot think ofany other possibility other than the outgassingthat we find in comets, which seems to be ruled out because we don’t see a cometary tail, or the pressure from the sunlight. There is no other proposalon the table right now. Narrator: Pressure from sunlight. It works similarly to how wind pushes against a sail on a boat. So too can sunlight pushagainst a spacecraft to propel it through space.
Incidentally, we call thesespacecraft solar sails. There’s just one catch. Pressure from sunlight is extremely light. Lighter than the weightof a fly on your hand. Which means in orderfor it to be effective, solar sails also have to beextremely light and thin. In 2010, for example, Japan’s space agency launched its Ikaros solar sail, which only weighed 1.1 pounds. But it eventually managed totravel over 65 million miles from Earth on just sunlight alone.
And it’s this type of forcethat the Harvard scientists think could be propelling Oumuamua too. Of course, that’s ifit’s an alien made sail in the first place. Loeb: Well first ofall, I am not confident that this is the correct interpretation because we don’t have enough data. And so this is one possibility. I would highly recommendpeople to read the paper.
If they have a better idea,they should publish it. Narrator: And as always,not everyone agrees with Loeb’s hypothesis. Weryk: I think that their explanation, I think it’s in contrastwith what the data says. You know, we did consider that possibility in our own paper, whichwas published earlier, and we dismissed it as notbeing physically valid.
You know again, there’s noreason to think Oumuamua is anything but a natural object. Narrator:That’s Rob Weryk, who first discovered Oumuamua in 2017. Weryk: So we think Oumuamua still has ice and the sublimating icegives it a small tiny kick that gravity alone wouldn’t account for, but that the dust it has is much larger than what comets typically have. And so we just don’t seethat from the ground. Narrator: And yes, in allprobability, he’s right.
Oumuamua is a natural object, like a comet or asteroid. But neither Weryk norLoeb can know for sure without more data. And sadly, Oumuamua is on itsway out of the solar system beyond the reach of our telescopes. So the best bet for solving this mystery? Weryk: So for Oumuamuaitself, it’s basically gone, it’s too faint to see from the ground.
There’s no way we couldsend a spacecraft mission, so we really have to find a second object. That would help answer a lot of questions that we don’t know. You know, I’m very interestedin finding a second one. It’d be nice if I found them all. Narrator: And Loeb already has some ideas on where to look next.
Loeb: There should be quite a lot of them right now in the solar system. And some of them could betrapped by Jupiter and the sun that act as a fishing net. And so some of these interstellar objects are bound to this solar systemafter the first passage. Narrator: That’s right. Some of these interstellar objects might be right here in our solar system, trapped, and waiting to be found. It looks like astronomers may have more fascinating discoveries to come.
A treasure troveof planets found Astronomers are celebratinga new discovery. Sean Carey, Manager, SpitzerScience Center, Caltech IPAC The big news is thataround a very nearby cold, small star wefound seven rocky, Earth-sized planets, all ofwhich could potentially have liquid water. Three of them orbit inthe habitable zone around the star.
And liquid water could exist onany of the seven planets given the right conditions. Nikole Lewis, James WebbTelescope Project Scientist, Space Telescope ScienceInstitute For me it’s mind-blowing. The first time I saw whatthe system had in it, I was just like, “You got to bekidding me!” Then I looked atthe data myself. I’m like, “Yup,there they all are.” It’s just, I would havenever predicted this. It’s beyond, you know, anythingI could’ve ever dreamt of.
The planetary systemis called TRAPPIST-1 after the Belgian-operatedtelescope in Chile. TRAPPIST found twoplanets in 2016. NASA’s Spitzer SpaceTelescope, with the help of ground-based telescopes,discovered five more. Michael Gillon, PrincipalInvestigator, TRAPPIST, University of Liege, Belgium I felt super-excited. Amazed by the very existenceof this system… was kind of… ofyeah… of shock. The TRAPPIST-1 planets areextremely close to one another.
From a planet’s surface you could easily see otherTRAPPIST-1 planets in the sky. If you were standing onone of these planets you’d actually see a lot of them sort of in the sky whipping by on these very shortorbital periods. NASA’s James Webb Telescope,launching in 2018, could teach us even moreabout the TRAPPIST-1 system. It will be able to detectthe chemical fingerprints of water, methane and oxygen ofpotential atmospheres, key ingredients inassessing habitability. It is an excellent,fantastic discovery. All images of planets areartist’s conceptions. Jet Propulsion Laboratory California Institute ofTechnology