Last week, astronomers announced the discovery of DeeDee, a possible dwarf planet. That name–dwarf planet–means it is like Pluto: Massive enough to assume a spherical shape due to its own gravitational force, but not quite big enough to control the region of space it inhabits. And it too circles the sun, but from much, much farther away than Pluto. A single orbit takes 1,100 years, making DeeDee the second-most distant dwarf astronomers have ever discovered.

The Internet’s scientific diaspora got excited for DeeDee. New worlds, even tiny ones, are special. But eventually, they won’t seem so. Scientifically, DeeDee is mainly important as a data point–an addition to a growing catalog of similar objects. And–like a census–as the catalog grows, the individuals listed therein will become less interesting. Which might sound sad but is actually a sign that astronomy is succeeding. Dwarf planets were only created as a class a decade ago, and it’s only a matter of time before you don’t care that somebody found a new one.

Dark energy delivers

When University of Michigan astronomer David Gerdes began the research that would eventually yield this big rock that might be a small planet, his goal was (and still is) larger. He wanted to use data from a dark-energy survey to find “trans-Neptunian objects”–anything orbiting beyond Neptune that is neither a planet proper nor a comet. He started combing through observations from a Chile-based instrument called the Dark Energy Camera.

The camera, as you might guess, is meant to study dark energy. But, says Gerdes, “fundamentally, what we’re doing is making a big, detailed map.” And in that map, Gerdes’s team looked for points of light that moved from night to night. This suggests they are small objects orbiting the Sun, rather than huge, bright objects moving incredibly fast through some distant part of the universe.

In an initial search of just one percent of the survey’s sky area, they found five new trans-Neptunian objects. And with that proof of concept, they decided to expand, searching a couple thousand square degrees of sky. (If you extend your arm all the way, the tip of your pinkie covers approximately one square degree of sky.) That larger patch contained a few hundred candidates. One of which stood out: 2014 UZ22, affectionately called DeeDee for “distant dwarf.”

Gerdes and his team spotted DeeDee when it was more than 90 astronomical units away–90 times the average distance from Earth to the Sun. To show up from that far away, it had to either be small and very shiny, or big and less reflective. Given those parameters, DeeDee is somewhere between 350 kilometers (very shiny) and 1,200 kilometers across (pretty dull). New, still-in-process data from the ALMA telescope in Chile, which can detect infrared light, should help pin down the dwarf’s size and shininess.

That’s all fantastic. But what’s most fantastic: Dwarf planets like DeeDee are becoming more and more discoverable, in general.

Abundance in the outer solar system

Scientists didn’t demote Pluto to dwarf planet out of spite. They were matching it to its context. When more powerful telescopes showed them more of the outer solar system, they realized Pluto was one of many icy, rocky bodies lurking far from the Sun. In 2004, astronomers discovered Sedna, about 40 percent as wide as Pluto.

A year later, they found Eris, an object bigger than Pluto. The name–Greek goddess of strife and discord–was appropriate. Instead of turning Eris into the 10th planet, astronomers at the contentious 2006 International Astronomical Union conference created a new category of thing: the dwarf planet. Pluto and Eris both became that thing.

Today, the International Astronomical Union recognizes five dwarf planets–Pluto, Eris, Ceres, Haumea, and Makemake. Mike Brown, the self-described “Pluto-killer,” claims six more objects are “nearly certainly” dwarf planets. His site lists almost 1,000 more, with dwarf planet statuses ranging from “highly likely” to “possibly.” So while finding a new potential dwarf like DeeDee is laudable, its addition to the catalog is now just that: an addition to the catalog.

Statistics are significant

This move from curiosity to category is not a thing to be mourned, which Gerdes would agree with (after all, he found the one while searching for the many). A lone object could be an outlier. But with a bunch, scientists can study the population; conclusions become generalizable. It’s why a government takes a census instead of publishing 350 million individual biographies. It’s why a medical trial doesn’t just recruit one poor participant. In transitioning to something that can be measured in aggregate, dwarf planets join pretty much every other astronomical object ever.

How many stars can you name? How many galaxies? “[The] saying has been ‘In astronomy, one is a pet rock, 10 a solid statistical sample,'” says astronomer William Keel.

Just last week, scientists announced that the universe contains 10 times as many galaxies as they previously thought–up from around 200 billion to 2 trillion. To do that, they didn’t actually have to discover billions of new galaxies: They looked deeply into the sky and extrapolated. Scientists know enough about galaxies, and know of enough galaxies, to deal in math.

Astronomical objects–from space rocks to star systems–are most notable as individuals when scientists weren’t expecting them and have to scramble to explain. That scramble usually means finding more examples, reaching “solid statistical sample” status, and then doing statistical science.

Dwarfs explain the universe

Alone, DeeDee is a shiny thing far, far away. Combined with other dwarfs and trans-Neptunian objects, it can help reconstruct the recipe from which the solar system was baked. DeeDee, Pluto, Haumea, Makemake, Ceres, and all the future dwarf planets that will get only number-names are the solar system’s leftover ingredients. They and their smaller companions are the dusting of sugar and flour left on the counter after the dough has accreted into cookies.

“[They] are kind of the primordial globs of stuff that formed the rest of the planets,” says Gerdes, “and so by studying them and how they’re distributed and what their sizes and compositions are, and the dynamics of their orbits, we can learn about that primordial solar nebula out of which we and the other planets coalesced.”

Still, the surprises aren’t done. Scientists will inevitably find dwarfs and subdwarfs that will make them go, “Huh.” And they’ll have a meeting, and that meeting will have a bunch of arguments, and eventually they will agree to create new subclasses to explain and contain these new, weird little worlds.

DeeDee, Gerdes says, is delightful in its own right. But it’s also tautological proof: Because they found DeeDee, they can find more stuff like DeeDee, more Makemakes, more Plutos. And those objects–all the spilled flour and sugar–might someday reveal the solar system’s secrets.


  1. The IAU’s definition does say anything about who would win a collision, or who is the biggest object, just that to be a “planet” the object’s orbit must be clear. Ceres is obviously the biggest object in the asteroid belt, and would win any collision with any other asteroid, but it is not considered a “planet” because it has not cleared its orbit. Since Pluto crosses the orbit of Neptune, then clearly neither Pluto nor Neptune can be construed as “planets” under the IAU’s inane definition.

  2. Except that there are not even 8 planets in the entire universe, because none of them have completely cleared their orbit. For example, Jupiter has both the Greek and Trojan asteroids in its orbit, and if Pluto is not a planet because Neptune is in its orbit, then conversely Neptune cannot be a planet because Pluto is in its orbit. Even the Earth has objects in its Lagrange Points 4 and 5, so it cannot be a planet either. The IAU’s definition of a “planet” is entirely moronic.

  3. Correct.

  4. And thus we get the goofy notion that there are only 8 planets in the entire universe.

  5. Well done laurele. This tale you have recounted is not stated enough. Politics is to blame, and when one pushes politics into science, one gets silly conclusions. Like suggesting that there are only 8 planets in the entire universe.

    Its like that time, way back when, they wanted to state that “stars” are those points of light in the night sky which are only visible to the naked eye, everything else (as the stars seen through a telescope) is not a star.

  6. The reverse is not true because in a collision Neptune would win and the resulting planet that formed from the collision would be mostly Neptune and not Pluto. So long as you’re the biggest object in your orbit, and you’re big enough to be a planet then you’re the planet, everything else that formed a sphere due to their own gravity in your orbit is just a dwarf planet.

  7. Thank you, AK_User, as I said we know that for a fact.
    So mow we measure the distance between the earth & the satellite by the same laser measurement equipments. One on the satellit shooting down to the earth, and one on the ground shooting up to the satellite.

    The distance is calculated by dividing the speed of light by the time how long for the laser beam to takr to go & back, and time on earth or time on the satellite are used to calculate each respectively. But they’re time dilated relatively.
    So what do you think? These measured two times are same or different?
    D = c / t.

  8. The time on Earth is different than the time on the satellite. Special Relativity predicts that the on-board atomic clocks on the satellites should fall behind clocks on the ground by about 7 μs/day (microseconds per day) because of the slower ticking rate due to the time dilation effect of their relative motion (the satellites are orbiting at ~14,000 km/h compared to Earth’s rotation of 1,675 km/h). Furthermore, the satellites are in orbits high above the Earth, where the curvature of space/time due to the Earth’s mass is less than it is at the Earth’s surface. A prediction of General Relativity is that clocks closer to a massive object will seem to tick more slowly than those located further away. A calculation using General Relativity predicts that the clocks in each GPS satellite should get ahead of ground-based clocks by 45 μs/day. The combination of these two relativistic effects means that the clocks on-board each satellite should tick faster than identical clocks on the ground by about 38 μs/day (45 – 7 = 38).

  9. Based upon the IAU’s definition there are no “exo-planets” because they do not orbit our sun. According to their definition, only objects that orbit our sun can be construed as “planets.”

  10. You need to include a maximum size as well.

    A planet…
    1) Is in orbit around its star;
    2) Has achieved hydrostatic equilibrium; and
    3) Is not massive enough to fuse deuterium.

    Without a maximum size for a planet, you would end up with brown dwarfs and even other stars or black holes falling into the definition of a “planet.”

    Beyond that, you can use whatever adjectives you want to describe this planet – dwarf, minor, ice, giant, gaseous, etc., etc. They are all planets. That would make everything from the size of Ceres to approximately 13 Jupiter masses a “planet” if it is orbiting its own star. If it meets the last two definitions, but not the first, then it is a “rogue” planet.

  11. If Pluto is not considered a “planet” because of Neptune being in its orbit, then is not the reverse also true? Neptune cannot be construed as a “planet” under the IAU’s definition because it has not cleared Pluto from its orbit. Furthermore, if you look at the Lagrange Points 4 and 5 of each of the “planets” in our solar system, you will find objects that have not been cleared from their orbit as well. Particularly Jupiter, which has the Greek and Trojan asteroids in its orbit. Therefore, under the IAU’s inane definition, there are NO planets within our solar system.

  12. Nathan Dunning

    Have you heard of NIBIRU or NEMESIS? apparently they are the cause of the climate change we’re experiencing.That you need infrared to see but it’s in our solar system Now??

  13. I have a question. There’re many smart people here so I thought this place is a good place to ask.
    There’s the reflector on the noon left there by one of the Apollo Moon Missions years ago. Today we could shoot a laser beam at it and the light reflects off back to the earth, and we can measure the time it takes to go & back to figure out the distance between the earth & the noon very precisely. (This is where I got my question from.)

    Ok. A thought experiment, we attached a reflector at a sattelite (any) in the orbit and shot the laser beam to measure the distance between the earth & the satellite precisely.
    2nd, we placed the same laser beam measurement equipment on the satellite and shot the laser beam down to the earth and we placed the reflector on the ground so that the satellite can measure the distance, too.
    I assume that time here on earth was used to measure how long it would take to go & back when we shot from here on earth to the satellite. And I also assume that time on the satellite was used to measure the time when we shot from the satellite to the earth to measure.

    We know for a fact that there’s time dilation between the ground on earth and the on the satellite (GPSs). Here is the question.
    Measured T /earth & T /satellite would be different or same?
    My personal understanding of the special relativity tells me that they must be same since / if there is the only one physical distance between the earth & the satellite, because the speed of light is a constant to all observers.
    But … Time here on earth is ticking a bit slower than time on the satellite relatively. Do you see my conundrum?

    I’d appreciate any comment, any help on this one.

  14. Scott Kellogg

    Using the “Clear the orbit” definition, we should technically not be calling Exo-planets “Planets” because we don’t know if they’ve cleared their orbits. Even Hot Jupiters are not “Planets” until we know.

  15. Stranger in the Alps

    Very well stated, except for the notion that Wired is, or intends to be, objective.

  16. Seek help. Your derangement syndrome is out of control.

  17. By this definition, Earth is a Dwarf Planet.

  18. If that object exists, it would be more like Planet 19 than Planet 9. Our solar system already has more than eight planets. Including dwarf planets, it has a minimum of 13 planets and counting.

  19. Unfortunately, you’re presenting only one side of an ongoing debate about Pluto and dwarf planets. “Scientists” did NOT choose to demote Pluto. Only four percent of the IAU did this, and most were not planetary scientists but other types of astronomers. Their decision was immediately opposed by an equal number–several hundred–professional planetary scientists in a formal petition led by New Horizons principal investigator Alan Stern.

    Ironically, Stern is the scientist who first coined the term dwarf planet, but he did so to designate a third class of planets in addition to terrestrials and jovians, not to designate non-planets. The four percent of the IAU that voted on this essentially misused his term.

    Stern and the planetary scientists who continue to reject the IAU decision do so based on preference for what is known as the geophysical planet definition. This definition rejects the notion that an object has to control its region to be a planet. That “requirement” is inherently biased against objects in distant orbits from their stars, and it gives primacy to an object’s location instead of its intrinsic properties. In contrast, the geophysical planet definition states that any celestial object that orbits a star, floats freely in space, or even orbits another planet, that is not a star itself and is large enough and massive enough to be rounded by its own gravity is a planet. By that definition, ALL dwarf planets are simply a subclass of planets.

    The IAU definition did not “match Pluto to its context” because Pluto is NOT just one of many icy bodies lurking in the outer solar system. The overwhelming majority of these bodies are tiny, shapeless rubble piles, nowhere near large enough to be rounded by their own gravity. In contrast, Pluto is 70 percent rock and is a complex world with the same processes as its larger planet counterparts. It has geology and weather; it appears to have clouds; it is geologically differentiated into core, mantle, and crust; it has cryovolcanism; it has an atmosphere composed of multiple layers of haze; it is active geologically, and it may even have a subsurface ocean. Blurring the distinction between a complex world like Pluto and the millions of tiny KBOs is simply bad science.

    Additionally, your statement that Eris is larger than Pluto is incorrect and is six years out of date. Eris was initially thought to be larger than Pluto, but in late 2010, a team of astronomers led by Bruno Sicardy observed Eris occult a star and determined it is marginally smaller than Pluto. This does not change the fact that according to the geophysical definition, Eris is a planet of the dwarf planet subcategory, as are Ceres, Haumea, and Makemake. It is not yet clear whether this newly discovered “DeeDee” is large enough to be spherical; it it is not, then it is not a dwarf planet.

    It is disappointing that you repeat Mike Brown’s completely unprofessional reference to himself as the “plutokiller.” Brown did NOT “kill” planet Pluto, and his use of this term has amounted to a sensationalizing of this debate for personal gain in terms of money and fame. Brown does not even study Pluto; he studies other dwarf planets. You would have done better to quote the leading scholar on Pluto in the world, Alan Stern.

    The IAU vote is not something to be mourned or to be blindly followed; it is a highly flawed definition that states dwarf planets are not planets at all, and it deserves to be questioned and challenged. Dwarf planets are a subcategory of planets just like dwarf stars are a subcategory of stars, and dwarf galaxies are a subcategory of galaxies. Next time, please report both sides of this issue, as an objective journalist should always do.

  20. JapaneseRamenNoodle

    I still don’t like the “dwarf planet” classification — even if I understand the rationale for it. The idea that Pluto is not a “planet” because it hasn’t “cleared its orbit” is preposterous because NO planet (including rocky planets larger than Earth) so far out would have the mass to have cleared its orbit (outside of massive gas planets).

    Take the “Planet 9” that may or may not exist in our solar system. Even with the mass and size that it is hypothesized to have, it is still not enough to clear its orbit. Moreover, there are “rogue planets” that have no orbits at all. What’s more, this classification cannot properly categorize planets orbiting other stars.

    I would rather implement a simple classification system. It would be somewhat similar to the current IAU definition and include the following:

    A planet is…
    1.) A celestial body that is in orbit around a local star; and,
    2.) Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape; and,
    3.) Has an equatorial radius of greater than 1000 km.

    *This definition would result in an even ten “planets” in our solar system — the current eight with the addition of Pluto and Eris. The other smaller objects that mean #1 and #2 but not #3 would be known as “minor planets.” Part of the rationale is that the larger planets will likely continue to “grow” over each megaannus until they eventually have reached sufficient mass to clear their orbits anyway.

    I would also entertain a different classification in the form of a system. It would look like the following and apply to planets in our solar system and elsewhere:

    1.) Class A planet – Planet that orbits local star or stars, has sufficient mass for self-gravity and a radius of greater than 1000 km.
    2.) Class AA planet – Same definition as above plus evidence of liquid water (possibly Mars).
    3.) Class AAA planet – All of the above but with plant or microscopic life.
    4.) Class AAA+ planet – Same as AAA but with animal life (i.e., Earth).
    5.) Class B planet – A planet that orbits local star or stars, has spherical shape but radius greater than 350 km (potato radius) and less than 1000 km (Class A planet).
    6.) Class C planet – A rogue planet that does not orbit a star or stars.
    7.) Class X planet – A planet whose existence has yet to be proven but for which there is ample evidence that it may exist (i.e., Planet Nine) -or- a planet for which its category is unknown.

    *In addition, each planet can be classified as a “gas” planet too. For instance, Jupiter would be a Class A gas planet while Venus would be a Class A planet. Most of the planets that have been “discovered” are Class X gas planets.

  21. Ronnie Smith

    That is not right. what if I am a trans who believes he 7ft 6″ tall, and the greatest basket ball player on earth and in history. they have to gvie a contract

  22. Ronnie Smith

    Soon you won’t care about a newly discovered dwarf planet. True.if Clinton is elected president of the USA we might not have a planet to view dwarfs from

  23. William Maddock

    The more crowded that region of the solar system is (not by discovered numbers, but by actual, existent numbers; just because we haven’t seen it doesn’t mean it isn’t there) the more difficult and dangerous exploring out there is going to be (because there’s more pin-balls out there with, possibly, your name on them). The more knowledge we have about that region, more informed our decision regarding exploration will be.

  24. Imagine the NBA declaring if you play outside the USA, are under 6 ft. and you can’t dunk, you are no longer a qualified basketball player. You are now a dwarf player.

    The body of expert astronomers (we prefer to think of it as a dwarf body) responsible for naming what’s out in space has rejected “plutoid” in favor of a bigger put-down, “ice dwarf.”

    Poor Pluto, forced to be introduced at any gathering of celestial bodies with the introduction, “Meet Pluto, the ice dwarf.”

    From ” At last we know something about Pluto. And astronomers.”…

  25. Strongly agree that the term dwarf planet is a crude and unhelpful construct. These bodies should be classified with primary regard to their history and composition, not their shape and orbit, which are largely accidents of physics. Any taxonomy that lumps Ceres and Dee Dee together will never contribute to science.

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