Discovery of 'Goblin' Solar System Object Bolsters the Case For Planet Nine (gizmodo.com)

Astronomers have discovered a dwarf planet, dubbed "the Goblin," in the outer reaches of the Solar System that never gets any closer to the Sun than 6 billion miles. Some experts say its orbital configuration points to the existence of Planet Nine, a hypothetical planet in our Solar System that is estimated to be about 10 times the mass of Earth. Gizmodo reports: The Goblin, or 2015 TG38 as it's more formally called, is what's known as an extreme trans-Neptunian object, or ETNO. As the moniker implies, these objects, of which there are potentially thousands, are located well beyond the orbit of Neptune. The researchers who discovered the object, a team led by Scott Sheppard from the Carnegie Institution for Science and Chadwick Trujillo from Northern Arizona University, estimate that the Goblin is around 185 miles (300 kilometers) in diameter. At this size, it could very well be sphere-like in shape. Its mean distance from the Sun is about 80 astronomical units (AU), where 1 AU is the average distance from the Earth to the Sun. That's 7.45 billion miles, or 12 billion kilometers.

The Goblin's extreme orbital path means it never comes close enough to impose gravitational influence on the Solar System's giant planets, like Neptune or Jupiter. And at the astounding distance of 2,300 AU, it gets slotted into an emerging astronomical category known as Inner Oort Cloud objects (IOCs), of which 2012 VP113 and Sedna are the only other two known members. [...] The discovery of 2015 TG38 is bolstering the case for Planet Nine -- a hypothetical planet, sometimes referred to as Planet X, that's allegedly several times larger than Earth and located hundreds of AU away. As noted in the new study, published today in The Astronomical Journal, the location of Goblin's perihelion is similar to what's observed with Sedna and 2012 VP113, along with other ETNOs. This is a clue to astronomers that something potentially big, i.e. a super-Earth, is pushing these objects into similar types of orbits.

Comments

Re:Sorry for the Pedantry

[Gavagai80]

There is actually a possibility of life in a planet X (or even in Pluto), if it has an internal ocean heated by radioactive decay. So it might be a bit of a paradise after all, on the inside, for all we know.

Re: 80 or 2300?

[CrimsonAvenger]

Both. Gets as close as 80 and as far as 2300. The orbit isn't exactly a circle

80 AU's is mentioned as the mean distance. NOT the minimum distance. If 80 AU's is the mean distance, and 2300 AU were aphelion (which is NOT what they said), the Goblin would have to have an orbit that pretty much brushed the Sun, took a few tens of thousands of loops around the Sun down near Mercury, followed by a close pass of Mercury that tossed it out toward Jupiter, then a close pass of Jupiter tossed it into the outer system to reach that 2300 AU level, then fall back to the Sun, close pass by Jupiter, another close pass by Mercury to keep it low for a few thousand years, lather, rinse, repeat.

Now, it's quite possible that they meant to write (and didn't, because they were idiots who didn't know what the words meant) that perihelion was 80 AU, and aphelion was 2300 AU.

Or someone cut & pasted from two articles to make this article. And one of the articles referred to one object, but the other referred to another....

Re:You mean planet 10?

[MBGMorden]

While all true, the distinction is generally only in how to choose to word our definitions.

I'd say Pluto is closer in "sameness" to Mars than Mars is to Jupiter, yet both Mars and Jupiter have been classified as planets while Pluto has not.

I don't have strong feelings about it either way, and to me anyone with strong feelings I view with suspicion. Arguing the definition had nothing to do with science and everything to do with language. And in general it seems that the primary reason for declassifying Pluto was that if Pluto was a planet then we'd have "too many" planets.

I find it comical though that the primary theory for Earth's moon formation was that there was a second "planet" orbiting in the same vicinity as Earth 1.0, the two collided, and the combined mass of the two formed current Earth with the debris scattered into orbit forming the moon. That means that by the current definition, neither of those bodies were planets prior to them colliding, since until that point neither had cleared out their orbit.