Outer solar system experts find 'far out there' dwarf planet

December 17, 2018, Carnegie Institution for Science
Artist concept of 2018 VG18, nicknamed "Farout." Credit: Roberto Molar Candanosa, Carnegie Institution for Science.

A team of astronomers has discovered the most-distant body ever observed in our Solar System. It is the first known Solar System object that has been detected at a distance that is more than 100 times farther than Earth is from the Sun.

The new object was announced on Monday, December 17, 2018, by the International Astronomical Union's Minor Planet Center and has been given the provisional designation 2018 VG18. The discovery was made by Carnegie's Scott S. Sheppard, the University of Hawaii's David Tholen, and Northern Arizona University's Chad Trujillo.

2018 VG18, nicknamed "Farout" by the discovery team for its extremely distant location, is at about 120 astronomical units (AU), where 1 AU is defined as the distance between the Earth and the Sun. The second-most-distant observed Solar System object is Eris, at about 96 AU. Pluto is currently at about 34 AU, making 2018 VG18 more than three-and-a-half times more distant than the Solar System's most-famous dwarf planet.

2018 VG18 was discovered as part of the team's continuing search for extremely distant Solar System objects, including the suspected Planet X, which is sometimes also called Planet 9. In October, the same group of researchers announced the discovery of another distant Solar System object, called 2015 TG387 and nicknamed "The Goblin," because it was first seen near Halloween. The Goblin was discovered at about 80 AU and has an orbit that is consistent with it being influenced by an unseen Super-Earth-sized Planet X on the Solar System's very distant fringes.

Solar system distances to scale showing the newly discovered 2018 VG18, nicknamed "Farout," compared to other known solar system objects. Credit: Roberto Molar Candanosa and Scott S. Sheppard, Carnegie Institution for Science.

The existence of a ninth major planet at the fringes of the Solar System was first proposed by this same research team in 2014 when they discovered 2012 VP113, nicknamed Biden, which is currently near 84 AU.

2015 TG387 and 2012 VP113 never get close enough to the Solar System's giant , like Neptune and Jupiter, to have significant gravitational interactions with them. This means that these extremely distant objects can be probes of what is happening in the Solar System's outer reaches. The team doesn't know 2018 VG18's orbit very well yet, so they have not been able to determine if it shows signs of being shaped by Planet X.

"2018 VG18 is much more distant and slower moving than any other observed Solar System object, so it will take a few years to fully determine its orbit," said Sheppard. "But it was found in a similar location on the sky to the other known extreme Solar System objects, suggesting it might have the same type of orbit that most of them do. The orbital similarities shown by many of the known small, distant Solar System bodies was the catalyst for our original assertion that there is a distant, massive planet at several hundred AU shepherding these smaller objects."

"All that we currently know about 2018 VG18 is its extreme distance from the Sun, its approximate diameter, and its color," added Tholen "Because 2018 VG18 is so distant, it orbits very slowly, likely taking more than 1,000 years to take one trip around the Sun."

Discovery images of 2018 VG18, nicknamed "Farout," from the Subaru Telescope on Nov. 10, 2018. Farout moves between the two discovery images while the background stars and galaxies do not move over the one hour between images. Credit: Scott S. Sheppard and David Tholen.

The discovery images of 2018 VG18 were taken at the Japanese Subaru 8-meter telescope located atop Mauna Kea in Hawaii on November 10, 2018.

Once 2018 VG18 was found, it needed to be re-observed to confirm its very distant nature. (It takes multiple nights of observing to accurately determine an object's distance.) 2018 VG18 was seen for the second time in early December at the Magellan telescope at Carnegie's Las Campanas Observatory in Chile. These recovery observations were performed by the team with the addition of graduate student Will Oldroyd of Northern Arizona University. Over the next week, they monitored 2018 VG18 with the Magellan telescope to secure its path across the sky and obtain its basic physical properties such as brightness and color.

The Magellan observations confirmed that 2018 VG18 is around 120 AU, making it the first Solar System object observed beyond 100 AU. Its brightness suggests that it is about 500 km in diameter, likely making it spherical in shape and a dwarf planet. It has a pinkish hue, a color generally associated with ice-rich objects.

"This discovery is truly an international achievement in research using telescopes located in Hawaii and Chile, operated by Japan, as well as by a consortium of research institutions and universities in the United States," concluded Trujillo. "With new wide-field digital cameras on some of the world's largest telescopes, we are finally exploring our Solar System's fringes, far beyond Pluto."

The Subaru telescope is owned and operated by Japan and the valuable telescope access that the team obtained was thanks to a combination of time allocated to the University of Hawaii, as well as to the U.S. National Science Foundation (NSF) through time exchanges between the US National Optical Astronomy Observatory (NOAO) and National Astronomical Observatory of Japan (NAOJ).

Explore further: New extremely distant solar system object found during hunt for Planet X

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Mark Thomas
4.8 / 5 (4) Dec 17, 2018
2018 VG18 is around 120 AU, . . . about 500 km in diameter, . . . (and) has a pinkish hue.


Awesome find! However, to discover such a small object 120 AU away makes me further doubt a Neptune-sized object ten times more massive than Earth could exist as the predicted Planet 9 between 200-1,200 AU away. It has been nearly three (3) years since Brown and Batygin predicted their Planet 9 from simulation, considerably longer than Brown predicted it would take to find Planet 9, but less than the current five year prediction.

https://en.wikipe...net_Nine
Nik_2213
5 / 5 (2) Dec 18, 2018
True. However, there are so many 'Field' objects in parts of the search zones that it may take a long trawl through pre-discovery images to confirm a candidate. Murphy's Law suggests such could hide in plain sight, 'dodging' between 'Field' stars, at least for several more years...
If found thus, I doubt even the most whimsical astronomer would dare name it 'Nyaah !' or 'Wally'...
;-))
torbjorn_b_g_larsson
not rated yet Dec 18, 2018
... to discover such a small object 120 AU away makes me further doubt a Neptune-sized object ten times more massive than Earth could exist as the predicted Planet 9 between 200-1,200 AU away. It has been nearly three (3) years since Brown and Batygin predicted their Planet 9 from simulation, considerably longer than Brown predicted it would take to find Planet 9, but less than the current five year prediction.


But the posterior probability went up, especially of the P9-shaped orbit family can be confirmed.

I have to disagree with the prediction window, since the current one is based on current information. (I dunno about an older window, but in any case updates is okay - Hubble was even headed to be out of this recently until the old gyro wheel they were forced to start up was fixed).

So, a cool - in several senses - body!
carbon_unit
not rated yet Dec 18, 2018
Wow! Voyager 2 is just reaching that distance, having launched in 1977. An admittedly quick look did not find whether or not it is within the heliosphere. Its aphelion is 168.7 AU with , but I don't know if that occurs on the bow shock side of the heliosphere or towards the 'tail' side. Perihelion is a mere 21.7 AU.

Silly name, Farout. What's the next one going to be Fartherout? Waaaayout?? Besides, I can't think that name without hearing it in the voice of the country dude in the movie Foul Play.
https://youtu.be/...Sfw?t=99
Mark Thomas
5 / 5 (2) Dec 18, 2018
Murphy's Law suggests such could hide in plain sight . . . at least for several more years.


Your point is we need a little more time to reach any firm conclusions. Makes sense to me, and personally, I am good with that. The search should be exhaustive and I hope Planet 9 exists and is found because it will increase our motivation to explore the distant outer solar system.

My point is simply given all the searching that has already occurred in the last 3 years, it is getting hard to believe a HUGE 10 Earth-mass planet is hiding between between 200-1,200 AU away. If 2018 VG 18 could be detected at 120 AU, a similar object 10 times bigger (diameter of 3,000 km) 10 times further away (1,200 AU) could also be detected. Planet 9 might be 10 times as big as that at ~30,000 km. For comparison, Uranus has a diameter of ~50,000 km and a mass 14.5 Earths.

So keep looking, but my money is on Planet 9 not being there.
Ultron
5 / 5 (1) Dec 18, 2018
I would easily bet 1000 USD that there no planet 9 with 10 Earth-mass around
rrwillsj
5 / 5 (1) Dec 19, 2018
It would be of mild interest if a giant Planet 9 was to be found.

No surprise if it turns out that there are instead, two or three sub-giants.
Whose orbits were close enough to have a combined gravitational effect.
Explaining why pinpointing Planet 9 has been so difficult,

"Ahh, that damn elusive Pimpernel!"

What would really be truly interesting? That would get my attention?
Is if it turned out that the Planet 9 phenomena was none of the above!

Saturn's moon, Rhea has uncommon isotopes of ice & is theorized to be an interstellar capture?

I am speculating if Planet 9 could turn out to be another interstellar capture?
& if not a giant or sub-giant?

Something a lot smaller then expected?
That might turn out to be a small body of exotic elements that have inordinate mass?
To have the predicted gravitational pull on the Outer System planetoids?

Kicked out from a supernovae, perhaps?
Now that would be worth sending a flight of robot prospectors!
rrwillsj
5 / 5 (1) Dec 19, 2018
& of course, a robot prospector will need a robot burro. As a wise-cracking wingman...
Mark Thomas
not rated yet Dec 19, 2018
I am speculating if Planet 9 could turn out to be another interstellar capture?


That is one possibility out of many. IMO, it is laughably naive that Brown and Batygin's simulation assumes the outer solar system is completely static over billions of years when even a quick look at Wikipedia informs us it is not.

https://en.wikipe...n_dwarfs
-See, "Distant future and past encounters"

The orbit stretching effect looks real enough, but there are so many possibilities for its source, e.g., thousands of passing stars and rogue planets over billions of years (maybe tens of thousands), some of which got pretty close.

https://en.wikipe...27s_Star
rrwillsj
5 / 5 (1) Dec 19, 2018
Well Mark, I know a common fetish among readers to this site are robot sex dolls. Just check out how many readers will access articles on that subject. But usually only a couple of hundred for mundane postings.

Me? I'd rather have one of those wisecracking robot burros. Better conversationalist, I'm sure!

Oh, & otto, you never did get back to me with that video of you trying to stuff a burro into a spacesuit.
Mark Thomas
not rated yet Dec 19, 2018
I know a common fetish among readers to this site are robot sex dolls.


rrwillsj, I probably wrote something that caused your mind to wander off-topic, but I have to say when that happens to you, it REALLY wanders off-topic. :-)
rrwillsj
5 / 5 (1) Dec 20, 2018
Oh Mark, please do not blame yourself when my mind wanders.The damn thing is practically a kaleidoscope!

Speaking of which... When everybody throws up their hands in frustration. Finally admitting defeat at they will never cease to discover new bodies of Oorten Hears a Who? in the Outer System.

I want to suggest that "Pimpernel" would be a glorious choice of a name for Planet 9!

& Mark, you might want to consider the meaning that several times as many visitors to this site, prefer to read about robot sex dolls. Rather than any of the other pop-science articles posted.
Ophelia
not rated yet Dec 20, 2018
r@mark thomas" "My point is simply given all the searching that has already occurred in the last 3 years, it is getting hard to believe a HUGE 10 Earth-mass planet is hiding between between 200-1,200 AU away."

Gravity is 1/r2. Not hard to believe at all.
rrwillsj
not rated yet Dec 22, 2018
Considering the distance from any light source?
& the the lack of internal heating precludes relying on infra-red to detect these snowballs?

They are as hard to spot as a kuroko on a kabuki stage!

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