The Planet X Hubbub
Two research teams each claim they potentially made discoveries of perhaps huge super-earth planets possibly near the edge of our solar system……maybe.
If you read that carefully you may get a vague sense that the jury is still out about exactly what the astronomers have detected.
This research was recently posted on the (in)famous arXiv pre-print online site .
So what are possibilities here and why is skepticism so warranted?
It all started with ALMA, the Atacama Large Millimeter/Submillimeter Array. This beast is one of the premiere instruments in astronomy and deserves a nice list of its many superlatives
It consists of 66 giant antennas on a plateau in the Chilean Andes
- It is among the highest observatories on the planet and the most expensive telescope in operation (that’s not in space)
- The movable telescopes can form images as sharp as a single 14,000 meter dish (with 10 times the resolution of the Hubble Space Telescope)
- It is the most powerful telescope for observing the cool universe (as in temperature, not awesomeness)
- It is designed to investigate planetary systems, distant galaxies, and could illuminate the origin of life.
Using ALMA, two separate teams were looking at stars in the Alpha Centauri and W Aquilae systems when they spotted something that caught their attention.
The Alpha Centauri team made an observation in 2014 and another in 2015 in which they spotted a bright source of light that, shockingly, had moved from one image to the next. A relatively close star could appear to move against the background of distant “fixed” stars but such a star could not have possibility escaped our attention for so long, especially if it were part of the alpha centauri trinary system. This permits the possibility that it is much smaller than a star but far far closer, perhaps in our own solar system. There are so many unknowns at this point that lots of different objects with different distances, sizes, and compositions could account for the measured brightness. The researchers mention the following possibilities:
1) A dark icy world that’s at least 100 AUs away (1 AU = 93 million miles—earth/sun distance)
2) A super-earth perhaps 300 AUs away
3) A very cool brown dwarf perhaps 20,000 AU away in our Oort cloud of comets
If one of those options caught your attention it’s probably the super earth one. This is a planet with a mass between that of earth and our small gas giants, Uranus and Neptune.
Ummm…holy crap, right? How intense would that be??
Could this be the Planet X that has been rumored for so long?
In the early 1900s, anomalies in the orbits of Uranus led to a search for what was called Planet X in our solar system. This led to the discovery of Pluto but its diminutive mass couldn’t account for the anomalies. Any serious searches for Planet X were mostly abandoned when astronomers realized that the weird motions of Uranus were ghosts caused by a miscalculation of the mass of Neptune. All was good. The term Planet X has now largely morphed to mean any full-fledged planet in our solar system that has not yet been discovered.
BTW, I think the brown dwarf option is pretty incredible as well.
The other research team I mentioned also found a bright spot in their data. They called this spot Gna after a speedy Nordic messenger goddess. This one also moved between the first and second observation. Their calculations put its distance at potentially 4,000 AUs. If it turns out to be that far away then it could certainly be a planet or a brown dwarf.
So that all seems fascinating and potentially, incredibly exciting but based on this research we need to seriously reign-in our expectations. I say this for the following reasons.
- Both groups of astronomers have submitted their research to the prestigious journal Astronomy & Astrophysics. At this time however it has not been peer-reviewed by other scientists nor published formally and so should certainly be considered preliminary at best.
- Both studies are based on only two observations with relatively little time separating them. The second group made a third observation and couldn’t even see the object.
- Finding such distant planets is incredibly difficult. In addition, the ALMA observations only viewed very tiny parcels of space. That such a small field of view yielded the discovery of a new planet so quickly in such a routine survey is quite statistically unlikely. Speaking of statistics, California Institute of Technology astronomer Mike Brown (who refers to himself as the “Pluto killer” since he discovered several large Trans Neptunian Objects that essentially dethroned Pluto) tweeted the following
“If it is true that ALMA accidentally discovered a massive outer solar system object in its tiny, tiny, tiny, field of view, that would suggest that there are something like 200,000 Earth-sized planets in the outer solar system. Which, um, no.”
If you need more convincing, later he tweeted…“Even better, I just realized that this many Earth-sized planets existing would destabilize the entire solar system and we would all die.”
After all these compelling reasons to assume Planet X has probably not been discovered, it seems much more likely that what ALMA detected was simply a blip or some noise that does not reflect anything real out there.
Regarding Gna, even the researchers have said that there may be “yet unknown, but significant, issues with ALMA observations.”
If these objects are real, the most likely interpretation is that these bodies are not far away and big but fairly small and nearby. There are many populations of icy bodies in the solar system. Gna researchers themselves say that their “blip” could be a centaur object between the orbits of Saturn and Neptune. Beyond Neptune we enter the realm of Trans Neptunian Objects. This region is often divided into three sections, the first being Kuiper Belt objects. Our friend Pluto resides here. Overlapping this area but extending far beyond it is another region called the Scattered Disk. This is home to dwarf planet Eris which is even more massive than Pluto. More than 1,200 icy/rocky objects have been found in the Kuiper belt and Scattered Disk with many thousands surely left to be discovered. This sheer preponderance of tiny worlds makes it much more likely in my mind that this is exactly what these scientists have found…if they have found anything at all.
Still it’s fun to think that they may have found something even bigger than earth so far from us yet still in our solar system…maybe, perhaps, possibly.
Image Credit: http://www.extremetech.com/extreme/219347-astronomers-claim-discovery-of-planet-x-in-outer-solar-system-others-not-so-sure