For the first time ever astronomers have studied an asteroid that has entered the Solar System from interstellar space. Observations from ESO's Very Large Telescope in Chile and other observatories around the world show that this unique object was traveling through space for millions of years before its chance encounter with our star system. It appears to be a dark, reddish, highly-elongated rocky or high-metal-content object. The new results appear in the journal Nature on 20 November 2017.
On 19 October 2017, the Pan-STARRS 1 telescope in Hawai`i picked up a faint point of light moving across the sky. It initially looked like a typical fast-moving small asteroid, but additional observations over the next couple of days allowed its orbit to be computed fairly accurately. The orbit calculations revealed beyond any doubt that this body did not originate from inside the Solar System, like all other asteroids or comets ever observed, but instead had come from interstellar space. Although originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it passed closest to the Sun in September 2017. The object was reclassified as an interstellar asteroid and named 1I/2017 U1 (`Oumuamua)[1].
"We had to act quickly," explains team member Olivier Hainaut from ESO in Garching, Germany. "`Oumuamua had already passed its closest point to the Sun and was heading back into interstellar space."
... [1] The Pan-STARRS team’s proposal to name the interstellar objet[sic] was accepted by the International Astronomical Union, which is responsible for granting official names to bodies in the Solar System and beyond. The name is Hawaiian and more details are given here. The IAU also created a new class of objects for interstellar asteroids, with this object being the first to receive this designation. The correct forms for referring to this object are now: 1I, 1I/2017 U1, 1I/`Oumuamua and 1I/2017 U1 (`Oumuamua). Note that the character before the O is an okina. So, the name should sound like H O u mu a mu a. Before the introduction of the new scheme, the object was referred to as A/2017 U1.
http://eso.org/public/news/eso1737
-- submitted from IRC. See also here.
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The solar system's first "interstellar interloper" has been named 1I/ʻOumuamua. It is the first known "hyperbolic asteroid" from outside the solar system:
The first known asteroid to visit our Solar System from interstellar space has been given a name. Scientists who have studied its speed and trajectory believe it originated in a planetary system around another star.
The interstellar interloper will now be referred to as 'Oumuamua, which means "a messenger from afar arriving first" in Hawaiian. The name reflects the object's discovery by a Hawaii-based astronomer using an observatory on Maui. It was discovered on 19 October this year by Rob Weryk, a postdoctoral researcher at the University of Hawaii Institute for Astronomy.
[...] Scientists who have made observations of 'Oumuamua, say that despite its exotic origins, the asteroid is familiar in appearance. In a paper submitted to Astrophysical Journal Letters, they argue that its size, rotation, and reddish colour are similar to those of asteroids in our Solar System. Measuring about 180m by 30m, it resembles a chunky cigar.
"The most remarkable thing about ['Oumuamua'] is that, except for its shape, how familiar and physically unremarkable it is," said co-author Jayadev Rajagopal from the US National Optical Astronomy Observatory (NOAO).
Also at the National Optical Astronomy Observatory and Scientific American.
Previously: Possible Interstellar Asteroid/Comet Enters Solar System
'Oumuamua's interstellar origin and unusually elongated shape has been enough to convince the billionaire-backed Breakthrough Listen to observe it to look for signs of alien technology:
The team's efforts will begin on Wednesday, with astronomers observing the asteroid, which is currently speeding away from our Solar System, across four different radio frequency bands. The first set of observations is due to last for 10 hours.
[...] Mr Milner's Breakthrough Listen programme released a statement which read: "Researchers working on long-distance space transportation have previously suggested that a cigar or needle shape is the most likely architecture for an interstellar spacecraft, since this would minimise friction and damage from interstellar gas and dust."
Andrew Siemion, director of the Berkeley SETI Research Center, who is part of the initiative, said: "'Oumuamua's presence within our Solar System affords Breakthrough Listen an opportunity to reach unprecedented sensitivities to possible artificial transmitters and demonstrate our ability to track nearby, fast-moving objects." He added: "Whether this object turns out to be artificial or natural, it's a great target for Listen."
Previously: Possible Interstellar Asteroid/Comet Enters Solar System
Interstellar Asteroid Named: Oumuamua
ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before
The interstellar asteroid 'Oumuamua's likely movements have been tracked based on the relative positions of nearby stars. Observations of 'Oumuamua indicate that it has only been subjected to interstellar conditions (cosmic rays, gas, dust) for hundreds of millions of years rather than billions. There are likely to be around 46 million such interstellar objects entering the solar system every year, most of which are too far away to be seen with current telescopes, and are quickly ejected:
[My (Fabo Feng)] latest study gives us a glimpse of exactly where 'Oumuamua may have come from. Reconstructing the object's motion, my research suggests it probably came from the nearby "Pleiades moving group" of young stars, also known as the "Local Association". It was likely ejected from its home solar system and sent out to travel interstellar space.
Based on 'Oumuamua's trajectory, I simulated how it has probably travelled through the galaxy and compared this to the motions of nearby stars. I found the object passed 109 stars within a distance of 16 light years. It went by five of these stars from in the Local Association (a group of young stars likely to have formed together), at a very slow speed relative to their movement.
It's likely that when 'Oumuamua was first ejected into space, it was travelling at just enough speed to break away from the gravity of its planet or star of origin, rather than at a much faster speed that would require even more energy. This means we'd expect the object to move relatively slowly at the start of its interstellar journey, and so its slow encounters with these five stars suggests it was ejected from one of the group.
Pleiades star cluster. "Code and results" for the arXiv paper.
We should capture as many interstellar asteroids as possible and smash them together to create a new dwarf planet near the Earth.
Previously: Possible Interstellar Asteroid/Comet Enters Solar System
Interstellar Asteroid Named: Oumuamua
ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before
Breakthrough Listen to Observe Interstellar Asteroid 'Oumuamua for Radio Emissions (none were found)
Astronomers have posited an interstellar origin for (514107) 2015 BZ509, the first example of a retrograde co-orbital asteroid with one of the solar system's planets (Jupiter):
An asteroid in Jupiter's orbit [Note: actually orbiting the Sun and crossing the orbit of Jupiter] may have come from outside our Solar System, according to a new study. Unlike 'Oumuamua, the interstellar object which briefly visited the Solar System earlier this year, 2015 BZ509 (affectionately known as BZ) seems to have been here for 4.5 billion years. This makes it the first known interstellar asteroid to have taken up residence orbiting the Sun.
It is not yet known where the object came from. "That's what we need to figure out next," laughs Dr Fathi Namouni from the Universite Cote d'Azur, one of the study's authors. "Because 'Oumuamua was just passing by... it's not that difficult to go back and pinpoint where it came from," he told BBC News. "BZ reached the Solar System when it was forming, when the planets themselves were not exactly where they are now. So it's a little more tricky to figure out where it came from."
Also at Scientific American, Science News, EarthSky, and CNN.
An interstellar origin for Jupiter's retrograde co-orbital asteroid (open, DOI: 10.1093/mnrasl/sly057) (DX)
Related: Possible Interstellar Asteroid/Comet Enters Solar System
Interstellar Asteroid Named: 'Oumuamua
ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before
Breakthrough Listen to Observe Interstellar Asteroid 'Oumuamua for Radio Emissions (none were found)
'Oumuamua Likely Originated in the Local Association (Pleiades Moving Group)
The interstellar space rock that mystified astronomers is actually a comet
A mysterious space rock, first spotted in 2017, bewildered astronomers — was it an icy comet, a rocky asteroid, or something entirely new? As the object, called 'Oumuamua, hurtles away from us, the mystery may be solved: it's accelerating like a comet.
Researchers tracked the space rock's trajectory on its way out of this solar system, using telescopes on the ground and the powerful Hubble Space Telescope to keep watch even as the interstellar visitor faded out of [sight]. They discovered that 'Oumuamua's speed couldn't just be the result of gravity. It was accelerating — which could be explained by gas puffing out of the sun-warmed end of a comet, the team reports today in the journal Nature [DOI: 10.1038/s41586-018-0254-4] [DX].
Also at ESA and ESA/Hubble.
Previously: Interstellar Asteroid Named: Oumuamua
ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before
Oumuamua Likely Originated in the Local Association (Pleiades Moving Group)
(Score: 1, Interesting) by Anonymous Coward on Wednesday November 22 2017, @03:46PM (7 children)
wikipedia: As of 2013, Voyager 1 was moving with a velocity of 17 kilometers per second (11 mi/s) relative to the Sun.
wikipedia As a result of its strong hyperbolic trajectory, Oumuamua will exit the Solar System in roughly 20,000 years.
Guys .... has an inclination of 123° with respect to the ecliptic,[n 4] and had a speed of 26.33 km/s (58,900 mph) relative to the Sun when in interstellar space, which peaked at 87.71 km/s (196,200 mph) at perihelion.[8][n 5]
this thing came in 9kps faster then voyager is leaving. it sped up by ~3.5 as it shot by the sun ... and now its written to take 20k yrs to leave our system?? how can that be? how fast is it now?
(Score: 1, Funny) by Anonymous Coward on Wednesday November 22 2017, @04:00PM
I think this means that we can look forward to 20,000 years of headlines every 2 or 3 years that Voyager has once again entered the heliopause.
(Score: 1) by khallow on Wednesday November 22 2017, @04:02PM (3 children)
The object was moving faster because it was deep in the gravity well of the Sun. And it'll take that long to leave the Solar System, because the latter is big.
(Score: 0) by Anonymous Coward on Wednesday November 22 2017, @04:23PM
exactly!! as our system radius is 50 years of voyagers big, Oumuamua would now be 50/20000 or 1/400th the speed of voyager.
from 1.5*Vs to Vs/400 is a lot of speed lost! ..... we're going to have space-races to this thing if its really this slow.
(Score: 0) by Anonymous Coward on Wednesday November 22 2017, @04:23PM (1 child)
Least helpful comment of the day. Compared to voyager having already "left the system" it doesn't make sense.
(Score: 2, Interesting) by khallow on Thursday November 23 2017, @03:27AM
Now that I have some extra time, I can explain things further. While there can some transfer of energy and momentum from Sun to object or vice versa, the general rule is that total energy is constant and hence, when an object drops down a deep gravity well, like the Sun's, it picks up a lot of kinetic energy and moves a lot faster. Similarly, as it climbs out of the gravity well to higher potential energy, it will slow down as kinetic energy declines.
It took Voyager 1 about 35 years to leave the heliosphere, the zone around the Sun dominated by the solar wind. This object will apparently do that in 20 years.
(Score: 4, Informative) by takyon on Wednesday November 22 2017, @04:27PM
If Planet Nine is real and 1,000 AU away (at time of approach), it would take over 180 years to get there at 26 km/s [wolframalpha.com].
Objects closer than the distance to the halfway point between Sol and Alpha Centauri could be said to be a part of our solar system. 2 light years / 26 km/s [wolframalpha.com] = ~23,000 years.
From Wikipedia:
I'd say that's about 0.65 AU per month. 156,000 AU in 20,000 years. That's 2.467 light years, more than half the distance to Alpha Centauri, although perhaps it is not aimed anywhere near Alpha Centauri.
There are probably some objects orbiting the Sun [wikipedia.org] at a maximum distance of 1 light year or more (only the most eccentric/cometary orbits are known since objects more distant than about 100 AU are undiscovered, but you can calculate the extreme aphelions of objects with close-ish perihelions):
Is it useful to say this thing will "exit the solar system" in 20,000 years? I don't know.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by inertnet on Wednesday November 22 2017, @11:40PM
No, V'ger has left the heliosphere (a number of times), which is different from the Sun's gravitational sphere.
(Score: 3, Funny) by bradley13 on Wednesday November 22 2017, @03:46PM (6 children)
" “the object is highly elongated: about ten times as long as it is wide ... dense, possibly rocky or with high metal content,"
Yep. [wikipedia.org]
Everyone is somebody else's weirdo.
(Score: 2) by JNCF on Wednesday November 22 2017, @03:58PM
That would be 9/4ths as long as it is wide, if "long" and "wide" are its largest and second-largest observable dimensions.
(Score: 0) by Anonymous Coward on Wednesday November 22 2017, @04:24PM (1 child)
It looks like Star Treks planet killer, or Cheech & Chongs new movie "Up In Space"
(Score: 2) by bob_super on Wednesday November 22 2017, @08:25PM
> Cheech & Chongs new movie "High In Space"
FTFY
(Score: 2) by mhajicek on Wednesday November 22 2017, @04:47PM (1 child)
Perhaps it's a Zentradi battle cruiser .
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 1) by Sulla on Wednesday November 22 2017, @05:08PM
Puny Micronian!
Ceterum censeo Sinae esse delendam
(Score: 2) by arslan on Thursday November 23 2017, @12:27AM
Reminds me of this scene from Austin Powers:
Johnson: [Noticing Dr. Evil's spaceship on radar] Colonel, you better have a look at this radar.
Colonel: What is it, son?
Johnson: I don't know, sir, but it looks like a giant--
Jet Pilot: Dick.
Dick: Yeah?
Jet Pilot: Take a look out of starboard.
Dick: Oh my God, it looks like a huge--
Bird-Watching Woman: Pecker.
Bird-Watching Man: [raising binoculars] Ooh, Where?
Bird-Watching Woman: Wait, that's not a woodpecker, it looks like someone's--
Army Sergeant: Privates! We have reports of an unidentified flying object. It has a long, smooth shaft, complete with--
Baseball Umpire: Two balls.
[looking up from game]
Baseball Umpire: What is that. It looks just like an enormous--
Chinese Teacher: Wang, pay attention!
Wang: I was distracted by that giant flying--
Musician: Willie.
Willie Nelson: Yeah?
Musician: What's that?
Willie Nelson: [squints] Well, that looks like a giant--
Colonel: Johnson?!
Johnson: Yes, sir?
Colonel: Get on the horn to British Intelligence and let them know about this.
Later, as Dr. Evil is escaping: Basil: Did we get Dr. Evil?
Johnson: No, sir. He got away in that rocket that looks like a huge--
Schoolteacher: Penis. The male reproductive organ. Otherwise known as tallywhacker, schlong or--
Dad: Weiner? Any of you kids want another weiner?
Son: Dad? What's that? points at rocket
Dad: I don't know, son, but it's got great big--
Peanut seller: Nuts! Hot salty nuts! Who wants some-- Lord Almighty!
Woman: That looks just like my husband's--
Ringmaster: One-eyed monster! Step right up and see the One-Eyed Monster!
One-eyed Monster: jumps out and scares crowd, then points to the rocket Hey, what's that? It looks like a big--
female Fan: Woody! Woody Harrelson? Can I have an autograph?
Woody Harrelson: Sure thing. [Sees rocket] Oh my lord.
Female fan: It's big!
Woody: Nah, I've seen bigger, it's--
Dr. Evil: (To Mini-Me) Just a little prick. It's a flu shot. You've been in the coldness of space.
(Score: 1, Interesting) by Anonymous Coward on Wednesday November 22 2017, @03:55PM (4 children)
Rama.
Well, one article I read noted that the brightness curve indicates it's rotating every 7.3 hours (iirc), I imagine end-over-end. For size, I got the impression of 1 standard football field (checked Wikipedia, and it lists 180 × 30 × 30 meters).
So it's a bit small for an O'Neill cylinder. I wondered if maybe it was designed for standing on either endcap as being "up" instead of along the sides, but 30 meters is really, really small. If it's aliens, it perhaps has a crew compliment of maybe 5 or so, just to pull a figure out of my arse. Assuming, of course, the Ramans are similar size to a human.
(Score: 0) by Anonymous Coward on Wednesday November 22 2017, @04:12PM (2 children)
Oh, for comparison if the Wikipedia dimensions are accurate, it's a bit bigger than the proposed Columbia-class of submarines [wikipedia.org]. Crew compliment of 155. Though we need to subtract from that to allow space for provisions necessary for an interstellar journey. So I'll keep my estimate at 5.
(Score: 2) by frojack on Thursday November 23 2017, @12:27AM (1 child)
5?
Maybe if the occupants are the size of dust mites.
No, you are mistaken. I've always had this sig.
(Score: 2, Informative) by khallow on Thursday November 23 2017, @08:58PM
The actual length of the object is roughly 400 meters and 40 meters diameter. That's 500k cubic meters which is roughly 540 ISS in volume. Then you're speaking of several thousand people living in the same concentrations as on the ISS.
(Score: 5, Insightful) by mhajicek on Wednesday November 22 2017, @04:49PM
Could fit a lot more crew if they're uploaded. Life support is easier too.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek