Sciency Words: FarFarOut

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we take a closer look at new and interesting scientific terms so we can expand our scientific vocabularies together!  Today’s Sciency Word is:


You know, I recently spent a couple days trapped at home due to a snow storm. Don’t worry, I don’t live in Texas—I wasn’t trapped in that snow storm.  Anyway, after reading a little about Dr. Scott Sheppard, I feel as though I seriously misused those snowed-in days.

Dr. Sheppard is one of the key players in the ongoing search for Planet X, also known as Planet Nine or (as I like to call it) New Pluto.  Together with fellow astronomer Chad Trejillo, Sheppard has discovered more than sixty objects of various sizes out beyond the orbits of Neptune and Pluto.

Among those sixty-plus objects Sheppard and Trejillo discovered is a possible dwarf planet nicknamed “FarOut” (official designation 2018 VG18).  FarOut is—or rather was, very briefly—the most distant natural object known to exist in our Solar System.  Hence the nickname.

But in early 2019, Sheppard was reviewing his data and happened to notice another object even farther out than FarOut.  As Scientific American tells the story, this happened while Sheppard was “snowed in during a blizzard.”  (I spent my recent snowed-in days watching cartoons on my phone.)  The new object Sheppard found in his data has the official designation 2018 AG37, but Sheppard nicknamed it “FarFarOut,” for obvious reasons.

According to this article from Carnegie Science, FarFarOut has a highly eccentric (non-circular) orbit, with an orbital period of approximately one thousand years!  Seriously, a thousand years!!!  A portion of that highly eccentric orbit is actually not that far away at all; at its closest approach to the Sun, FarFarOut’s orbital path actually crosses within the orbit of Neptune.

I do have to take issue with some of the news articles and social media posts I’ve seen about FarFarOut.  Strictly speaking, FarFarOut is not the most distant known object in the Solar System.  We should probably call it the most distant natural object, or the most distant non-articifical object, that we currently know about, because there is one known object that’s even fartherer out than FarFarOut.

Sciency Words: Sednoid

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Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us all expand our scientific vocabularies together. Today’s word is:


There are currently only two known sednoids. The first is Sedna (from which the word sednoid is derived). The other is named 2012 VP113 (or “Veep,” as I like to call it).

A possible third sednoid was discovered in late 2015. It has the fun, easy-to-remember name V774104. It may take a while for astronomers to determine V774104’s orbital path. It will take a bit longer for them to think up better names.

There’s a lot of ongoing debate over what exactly these two (or three) objects are. They might be former Kuiper belt objects, or they might be part of the Oort cloud, or they may even be objects captured from other star systems.

For our purposes, the defining characteristic of sednoids is that they keep their distance from the rest of the Solar System, coming no closer to the Sun than 75 AU. For the sake of comparison, Neptune orbits the Sun at a distance of approximately 30 AU, and the Kuiper belt terminates at a distance of about 50 AU.

This means sednoids are so distant that they don’t have any significant gravitational interactions with the eight known planets. As far as Sedna and Veep are aware, there may as well be no planets in the Solar System at all.

Ja10 Sednoid Secrets

Okay, the orbits of both Sedna and Veep are a little too strange. They’re too eccentric. Way too eccentric.

At perihelion (closest approach to the Sun), Veep is approximately 80 AU away; at aphelion (farthest distance from the Sun), Veep is over 400 AU away. Sedna’s orbit is even crazier, with perihelion at 75 AU and aphelion at a distance of over 900 AU!

It’s hard to believe the sednoids ended up in these bizarre orbits on their own, so they must have had gravitational interactions with something. If the eight known planets couldn’t have influenced the sednoids, does that mean there’s another planet out there? Could the elusive and controversial Planet X be responsible for these weird orbits?

Assuming Planet X exists at all.

P.S.: I’ve been highly skeptical of the whole Planet X thing, or as it is now being called the Ninth Planet hypothesis. However, after yesterday’s post on the clustering of scattered disk objects and today’s post on sednoids, I have to admit that something odd seems to be going on beyond Neptune’s orbit.

Planet Nine from Outer Space

Dang it, I thought I was finished exploring the Solar System. Now there’s another planet!?! Are we sure this isn’t yet another false alarm over Planet X?

To escape the hype over this alleged ninth planet, I decided to find the original source for this story, a paper entitled “Evidence for a Distant Giant Planet in the Solar System.” It was published on January 20, 2016, in The Astronomical Journal (click here).

First off, this paper does not announce the discovery of a new planet. Instead, it examines a peculiar trend astronomers have noticed in a region of the Solar System called the scattered disk (a region which partially overlaps the Kuiper belt). This odd trend is offered as circumstantial evidence that an extra planet might exist.

For the purposes of today’s post, I’ve named this hypothetical planet “Neo-Pluto.”

If Neo-Pluto is Real…

Billions of years ago, as the Sun shed its first rays of sunlight, a certain number of planets coalesced from the protoplanetary disk. That number was greater than eight. It was also greater than nine. A lot greater.

Like unruly children, these early planets jostled around in their orbits, pushing and pulling each other with their gravity, and sometimes colliding. One such collision led to the formation of Earth’s moon. Another probably knocked Venus into its retrograde rotation, and another may have tipped Uranus sideways.

Jupiter likely formed at the outermost edge of the protoplanetary disk, but it didn’t stay there. As this giant planet migrated inward, it wreaked havoc on the young Solar System. Smaller objects that wandered too close were either gobbled up, adding to Jupiter’s already considerable mass, or they were hurled out of the Solar System by Jupiter’s colossal gravity.

Neo-Pluto was one of those unlucky objects to be ejected from its original orbit, but it was not sent into total exile. It managed to stay within the gravitational influence of the Sun, and today it lingers in the cold depths of space, brooding over its fate.

Ja09 Neo-Pluto

But Neo-Pluto isn’t exactly a lightweight either. At approximately ten Earth masses, it has considerable gravity of its own, and the effects of that gravity have been noticed in the scattered disk.

Scattered disk objects (SDOs) are… well… scattered. They have highly eccentric (non-circular) and highly inclined (tilted) orbits; however, many known SDOs have almost the same perihelion (point of closest approach to the Sun). That can’t be a coincidence. It seems that just as Jupiter perturbs the orbits of asteroids in the asteroid belt, Neo-Pluto has pushed scattered disk objects into certain orbital trajectories, causing their perihelia to cluster.

Or so it seems. This all assumes that Neo-Pluto exists.

If Neo-Pluto Is NOT Real…

The authors of this “Distant Giant Planet” paper use a hypothetical planet to explain what’s happening in the scattered disk, and they clearly prefer that explanation, but they do acknowledge other possibilities.

  • Instead of one large planet, there could be a great many smaller planets and/or dwarf planets affecting the scattered disk.
  • A passing star might have disrupted the scattered disk long ago.
  • Observational bias may be at work, meaning that SDOs with a specific perihelion might be easier to see from out vantage point here on Earth. It’s unclear why that might happen, but a more thorough survey of the scattered disk could reveal a more random distribution of perihelia.

The best way to prove that Neo-Pluto exists is to find it. Alternatively, we could continue studying the scattered disk to see if this perihelion-clustering trend continues.

Until then, all we can say for certain is that the Solar System has at least eight planets.

P.S.: In part because of this latest new planet “discovery” as well as other rumored “discoveries” in recent months, today Sci-Fi Ideas is reposting my Sciency Words article on “Planet X.” Click here to check that out.

Sciency Words: Planet X

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Today’s post is part of a special series here on Planet Pailly called Sciency Words.  Every Friday, we take a look at a new and interesting scientific term to help us all expand our scientific vocabularies together.  Today’s word is:


Planet X is the name given to any hypothetical planet yet to be discovered in our Solar System.  Percival Lowell originally coined the term back in the early 1900’s.  Lowell is the same astronomer who thought he saw canals on the surface of Mars, “proving” the existence of a Martian civilization.

At one time, Uranus and Neptune could have born the Planet X title.  Scientists long suspected the existence of a seventh planet due to anomalies in the orbit of Saturn.  After Uranus was discovered, anomalies in its orbit hinted at the existence of Neptune, and anomalies in Neptune’s orbit hinted that there might be even more planets beyond it.

Recent data from the Wide-Field Infrared Survey Explorer, a.k.a. WISE, found no evidence of a Planet X, which seemed to put the matter to rest once and for all.  There are lots of dwarf planets out there, like Pluto and Eris, but nothing large enough affect Neptune’s orbit in any meaningful way.

Now NASA scientists are proposing the existence of Planet X again to explain anomalous perturbations in the orbits of two of the most distant known dwarf planets.  To be fair, WISE failed to detect any Saturn or Jupiter-sized planets.  This new Planet X would be much smaller, closer to the size of Earth or Mars.

It seems our Solar System just keeps getting more and more crowded.

9 Planets