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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.
(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.