The Ephemeral Search for The Real Planet 9

By The Metric Maven

This last Summer I visited Lowell Observatory in Flagstaff Arizona. I saw the telescope where Percival Lowell (1855-1916) convinced himself he saw canals on Mars. In science one can easily fall in love with a hypothesis and begin to see what you expect to see. After the Martian canals had been vanquished, and Perceval Lowell had passed away, a young Astronomer by the name of Clyde Tombaugh (1906-1997) took up his search for a ninth planet. Tombaugh painstakingly photographed the night sky and miraculously discovered a new planet (expected to be at least Earth-sized) in the expected area of the sky predicted in February of 1930. The amazing part, is how lucky Tombaugh had been. Pluto has a 17 degree tilt upward from the ecliptic, which means its not in the plane of the other planets—where one would expect to find it. Pluto was in a location where it was very close to the ecliptic—a rare occurrence. With an orbital period of 280 years, if Pluto had been in its farthest part of its orbit, Tombaugh would have gazed into empty space. In many ways he won a cosmic lottery ticket. The new planet  became known as Pluto and as PL is also the initials of Percival Lowell, it was greeted with open arms at Lowell Observatory. All was fine until a team, lead by Mike Brown (1965- ) at Cal Tech, located Eris which is much farther out from the Sun than Pluto, and appeared to be larger than Pluto, was, for a while, considered Planet 10, with Pluto still designated as Planet 9.

Better measurements slowly reduced the mass, size and mathematical need for Pluto to provide an explanation of the now nonexistent gravitational perturbations. As we all know now, Pluto is at best considered a dwarf planet in the Kuiper Belt. After Pluto’s change in categorization, it stopped being the last planet discovered, and became the first Kuiper Belt object discovered. Planet 9 then vanished in an organizational puff of smoke. The description of our solar system from the Sun to the hypothetical Ort Cloud looked quite fixed at that point. In 2010, astronomer Mike Brown wrote a book titled How I killed Pluto and Why It Had It Coming. He had been at the forefront of Pluto’s nomenclatureral demise. Then in January of 2016, he and Konstantin Batygin (1986- ),  would ironically propose the existence of a new planet, based on orbital perturbations,  the same type of evidence that began the search for Pluto by Tombaugh.

The new non-Pluto Planet 9 begins its theoretical existence with a large mass of 60 000 Yottagrams, and an orbital distance that varies from 30 000 Gigameters to 180 000 Gigameters. It has a semi-major axis of about 105 000 Gigameters. Gigameter is the natural  metric unit for describing the distances of planets in a solar system. Planet 9 is estimated to take about 10 000 to 20 000 years for a single orbit around the sun. Uranus, at 87 000 Yottagrams, is slightly more massive than the hypothetical Planet 9.

In June of 2017, Kat Volk, and Renu Malhotra, both from the University of Arizona, announced that computations they undertook indicate that a 10th planet exists. They estimate it is about 9000 Gigameters from the Sun and possesses a mass about that of Mars. Again, unexpected gravitational perturbations led researchers to suspect the existence of another planet, other than Planet 9.

In order to compare the two newly hypothesized planets, with our existing list of Planets, Kuiper Belt objects, and human created spacecraft; I have updated a table given in my essay Long Distance Voyager (about metric distances and the universe) which is presented below:

The first change I noticed is that if Planet 9 exists, Voyager 1 and Voyager 2 would no longer be “outside our solar system.” So are the Voyager Spacecraft still in interstellar space, or do we redefine them as inside our solar system? Categorization can be a difficult objective for astronomy, but where the Voyager spacecraft are, will probably not stir up the controversy that Pluto did when Eris was discovered. Eris is appropriately named for the Greek goddess of Strife and discord. The other categorization problem is that Planet 10 is well inside the orbit of Planet 9, so one would think they should swap numbers so Planet 10 is the furthest out and Planet 9 the next planet toward the Sun. Planet 10 also finds itself outside of the Kuiper Belt, and is probably a Trans-Neptunian planet, although how meaningful this designation would be remains to be seen. Planet 10 is between Pluto and Eris, and Planet 9 is the farthest hypothetical planet out by about an order of magnitude compared to Planet 10.

In many cases, astronomical masses outstrip the metric system, and one must resort to scientific notation, but in the case of our solar system, it might be useful to express the values using a large metric prefix. We will use Yottagrams, as that is the last magnifying metric prefix. Below is a table of Planetary Mass for selected objects in our solar system.

It is clear that Jupiter dominates the mass total of our solar system. One can estimate immediately that Jupiter is somewhere on the order of three times the mass of
the next most massive planet Saturn. Mercury, the smallest planet, is well over an order of magnitude more massive than Pluto or Eris. Pluto and Eris are an order of magnitude larger than Ceres the largest asteroid in the Asteroid Belt. It is clear that Jupiter, Saturn, Uranus, and Neptune form a Gas Giant mass class that is separate, and dominates all the other planets. The new Planet 9, should it exist, would be the runt member of this fraternity–unless it is not a Gas Giant, we then might need to implement a new designation from boxing and call them the Heavymass planets. The new Planet 10 would currently be grouped with the current Rocky planets, but from a distance perspective it would be the only member of this designation outside of the classical distance grouping of the inner and outer planets that are bounded on either side by the Asteroid Belt. Perhaps the less massive rocky planets could be called the Lightmass rocky planets, unless Planet 10 is gaseous? Whatever the Astronomical Union decides, the metric system is there for them, whether they use it, or not.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page.

Related Essays:

Long Distance Voyager

The Expanding Universe


The Metric Maven has published a book titled The Dimensions of The Cosmos. It examines the basic quantities of the world from yocto to Yotta with a mixture of scientific anecdotes and may be purchased here.


Starry Eyed Dimensions

By The Metric Maven

Bulldog Edition

My friend Dr Sunshine is very good at expressing and interpreting numbers. He has a favorite example from Star Trek IV: The Voyage Home (1986) that he uses to illustrate numerical importance:

Spock: [in response to Kirk pawning his antique spectacles from Wrath of Khan] Excuse me, Admiral. But weren’t those a birthday gift from Dr. McCoy?

Kirk: And they will be again, that’s the beauty of it.

[to Antique Store Owner]

Kirk: How much?

Antique Store Owner: Well, they’d be worth more if the lenses were intact. I’ll give you one hundred dollars for them.

Kirk: …Is that a lot?

Recently the farthest star ever viewed by a telescope was sighted. Phil Plait, Bad Astronomer, and worse metric user, attempted to impress his audience by saying:

This is incredible: Due to a quirk of cosmic geometry, astronomers have detected the light from the farthest individual star ever seen. How far away is it?

Over nine billion light-years away.

Yes, you read that right. Nine. Billion. Light-years.

A single star, from that distance. Holy yikes. Seriously, when I read about this the hairs on the back of my neck stood up. This is seriously amazing, so much so that for a moment I couldn’t believe it was real. Then I read the paper, played with the math a little, and, sure enough, this appears legit.

I was immediately uncertain just how far away this star is. A billion light years?—is that a lot? In my essay Long Distance Voyager, I use metric prefixes to categorize different astronomical items:

click to enlarge

I define nearby stars as those measured in Petameters (1015), and far away when measured with Exameters (1018). Long ago it stuck in my brain that the observable universe has a dimension that is in Yottameters (1024). So just how big is 9 billion light years? Well, knowing that a light-year is 9.4607 Petameters we multiply this by 9 billion (Giga-) and obtain 85 Yottameters! Wow, that is big. The farthest detected galaxy is about 126 Yottameters, and the diameter of the observable universe is about 880 Yottameters! This is one serious Yottasurprise. We can see two metric triads farther than the metric definition of far away stars! How on Earth, or actually how in the universe, did this happen?

Well, it is an interesting coincidence that allowed it. The star would normally be too faint to see, but a cluster of galaxies between the star and ourselves acts as a gravitational lens, which concentrates the light from that star enough for us to see it. Not only can we see it, the star has been identified as a blue supergiant, which is one of the brightest type of stars known. Rigel in the Orion constellation (lower right star) is a blue supergiant, but is at a distance of only about 8 Exameters from us. Deneb is 24 Exameters from us. One of the farthest stars ever seen is UDF 2457, which is 558 Exameters away; whereas the just discovered Lensed Star 1 (LS1) is 85 000 000 Exameters distant. The human eye can only detect a minute number of stars which are only about 10 Exameters from us, beyond that, individual stars fade into the blackness, hidden from our unaided gaze. Galileo was amazed at the number of normally invisible stars that his telescope allowed him to suddenly see. Keep in mind that our Galaxy is only about 1000 Exameters across, all the stars you see with your eyes are essentially local.

Einstein asserted that a large mass literally warps space. The closer one is to the large mass, the larger the amount of warping. On May 29, 1919, a group led by Arthur Eddington (1882-1944) and Frank Dyson (1868-1939) took a photograph during a total solar eclipse. Stars near the Sun changed their position with respect to stars further away. When images of the stars, taken when the Sun was absent, was placed over one taken by Eddington’s group during the eclipse, stars near the Sun were seen to be in a different position than those radially further away, and therefore less influenced by the Sun’s gravity. This bending of light has important uses in astronomy. When searching for planets that might have been ejected from their home solar systems into space, astronomers watch for a light-warped signature that a planet produces when passing in front of a star. In the case of LS1, lensing distortion occurs as it orbits around the center of the galaxy where it resides. The location of the individual galaxies that make up the “lensing cluster” are not homogeneous which also introduce undesired aberration.

The cluster of galaxies happen to be located in positions that add together (most of the time) in a way to capture and concentrate the light from this single star, and allow us to see an extra two metric triads (1 000 000) further in distance than is normally possible. Is that alot?—YES!

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page

Postscript: On 2017-08-24 Bad Astronomy posted an essay titled: A 500 TRILLION KM LONG STREAMER OF AMMONIA IN ORION. Is that a lot? Well, 500 Trillion Km is 500 Petameters, or a length that encompasses a distance to nearby stars in our own galaxy. When one uses Ye Olde English Prefixes with metric, it’s not even pigfish, it’s just fishy.

The Metric Maven has published a book titled The Dimensions of The Cosmos. It examines the basic quantities of the world from yocto to Yotta with a mixture of scientific anecdotes and may be purchased here.