The Discovery of 2003 UB313 Eris

8/6/2019 The Discovery of 2003 UB313 Eris

1/18

The discovery of 2003 UB313 Eris, the

10th planet largest known dwarf planet

Discovery images of the dwarf planet Eris. The three images were taken 1 1/2 hours apart on the night ofOctober 21st, 2003.

The Eris can be seen very slowly moving across the sky over the course of 3 hours.

Eris is 27% more massive than Pluto

2003 UB313 is now officially Eris!

Eris, the largest dwarf planet known, was discovered in an ongoing survey at PalomarObservatory's Samuel Oschin telescope by astronomers Mike Brown (Caltech), Chad

Trujillo (Gemini Observatory), and David Rabinowitz (Yale University). We officially

suggested the name on 6 September 2006, and it was accepted and announced on 13September 2006. In Greek mythology, Eris is the goddess of warfare and strife. She stirsup jealousy and envy to cause fighting and anger among men. At the wedding of Peleus and

Thetis, the parents of the Greek hero Achilles, all the gods with the exception of Eris were

invited, and, enraged at her exclusion, she spitefully caused a quarrel among the goddesses that

led to the Trojan war. In the astronomical world, Eris stirred up a great deal of trouble among

the international astronomical community when the question of its proper designation led

to a raucous meeting of the IAU in Prague. At the end of the conference, IAU members

voted to demote Pluto and Eris to dwarf-planet status, leaving the solar system with onlyeight planets.

The satellite of Eris has received the offical name Dysnomia, who in Greek mythology isEris' daughter and the demon spirit of lawlessness. As Dysnomia is a bit of a mouthful,

we tend to simply call the satellite Dy, for short.

As promised for the past year, the name Xena (and satellite Gabrielle) were simply

placeholders while awaiting the IAU's decision on how an official name was to be

proposed. As that process dragged on, however, many people got to know Xena and

Gabrielle as the real names of these objects and are sad to see them change. We admit to
http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.htmlhttp://www.gps.caltech.edu/~mbrown/planetlila/#erishttp://www.astro.caltech.edu/palomarnew/sot.htmlhttp://www.astro.caltech.edu/palomarnew/sot.htmlhttp://www.gps.caltech.edu/~mbrown/eightplanetshttp://www.gps.caltech.edu/~mbrown/planetlila/moon/index.htmlhttp://www.gps.caltech.edu/~mbrown/planetlila/moon/index.htmlhttp://www.gps.caltech.edu/~mbrown/planetlila/#erishttp://www.astro.caltech.edu/palomarnew/sot.htmlhttp://www.astro.caltech.edu/palomarnew/sot.htmlhttp://www.gps.caltech.edu/~mbrown/eightplanets


2/18

some sadness ourselves.We used the names for almost two years now and are having a

hard time swtiching. But for those who miss Xena, look for the obvious nod in the new

name of the moon of Eris.

Artists concept of the view from Eris with Dysnomia in the background, looking back towards the distant sun. Credit: Robert Hurt (IPAC)

What is it?

This new dwarf planet (see the now out of date "What makes a planet?" below) is thelargest object found in orbit around the sun since the discovery of Neptune and its moon

Triton in 1846. It is larger than Pluto, discovered in 1930. Like Pluto, the new dwarfplanet is a member of the Kuiper belt, a swarm of icy bodies beyond Neptune in orbit

around the sun. Until this discovery Pluto was frequently described as "the largest Kuiper

belt object" in addition to being a dwarf planet. Pluto is now the second largest Kuiperbelt object, while this is the largest currently known.
http://www.gps.caltech.edu/~mbrown/whatsaplanet/requiem.htmlhttp://www.gps.caltech.edu/~mbrown/planetlila/moonhttp://www.gps.caltech.edu/~mbrown/planetlila/moonhttp://www.gps.caltech.edu/~mbrown/planetlila/#planethttp://www.gps.caltech.edu/~mbrown/planetlila/lilalarge.jpeghttp://www.gps.caltech.edu/~mbrown/whatsaplanet/requiem.htmlhttp://www.gps.caltech.edu/~mbrown/planetlila/moonhttp://www.gps.caltech.edu/~mbrown/planetlila/#planet


3/18

Where is it?

The dwarf planet is the most distant object ever seen in orbit around the sun, even more

distant than Sedna, the planetoid discovered almost 2 years ago. It is almost 10 billionmiles from the sun and more than 3 times more distant than the next closest planet, Pluto

and takes more than twice as long to orbit the sun as Pluto.

A view of the solar system from the north down. The four circles show the orbits of Jupiter, Saturn, Uranus, and Neptune. The yellow dot in thecenter is the sun. The earth, if it were shown, would be inside the yellow dot representing the sun. The orbits of the two outermost planets,

along with their current positions, are also shown. If you are worried because the sun appears to not be the focus of the orbital ellipse you are

very observant! But it is just a projection effect. The see the full 3D orbit go tothis very nice web page

The dwarf planet can be seen using very high-end amateur equipment, but you need to

know where to look. The best way to find precise coordinates (of this planet, or any other

body in the solar system) is with JPL'shorizons system. Click on "select target" and thenenter "2003 UB313" under small bodies.

The orbit of the new dwarf planet is even more eccentric than that of Pluto. Pluto moves

from 30 to 50 times the sun-earth distance over its 250 year orbit, while the new planetmoves from 38 to 97 times the sun-earth distance over its 560 year orbit.

How big is it?

Usually when we first discover distant objects in the outer solar system we don't know for

sure how large they are. Why not? Because all we see is a dot of light, like the picture at
http://www.gps.caltech.edu/~mbrown/sednahttp://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2003+UB313&group=all&search=Searchhttp://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2003+UB313&group=all&search=Searchhttp://ssd.jpl.nasa.gov/cgi-bin/ephhttp://ssd.jpl.nasa.gov/cgi-bin/ephhttp://www.gps.caltech.edu/~mbrown/sednahttp://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2003+UB313&group=all&search=Searchhttp://ssd.jpl.nasa.gov/cgi-bin/eph


4/18

the top of the page. This dot of light is sunlight reflected off the surface of the planet

(interestingly the sunlight takes almost a day to get out to the planet, reflect off of it, and

get back to the earth!), but we don't know if the object is bright because it is large or if itis bright because it is highly reflective or both.

When an object is too far away to directly see how big it is, astronomers use an indirectmethod instead where they measure the heat coming from the object. If we wanted to

measure the size of a fire, for example, we could do it by measuring the total amount ofheat coming from the fire. The temperature of the flames in a match and a bonfire are

essentially the same, but a bonfire emits much more heat because it is much bigger. The

same is true of distant planets. Because we know how far away the planet is we have apretty good idea of the surface temperature (a frosty 405 degrees below zero!), thus when

we measure the total heat we can tell how big the object is. Unfortunately, the new planet

is so far away and so cold that our first attempt at measuring the heat, using the SpitzerSpace Telescope, could not detect the heat output. This fact tells us that the object must

be smaller than about 3300 km.

In the meantime, observations have been made by a group from the University of Bonnfrom the 30-meter IRAM telescope. This telescope, like Spitzer, measures the heat

output. IRAM measures the heat output in a region of the spectrum where much less heat

is given off, but IRAM is a much larger telescope than Spitzer. The observations weresuccessful in finally detecting the heat of Eris. From the amount of heat measured they

determined that Eris has a diameter of 3000 +/- 400 km. A very nice discussion of the

measurement and what the uncertainties mean can be found at thepress release webpage.

The newest size measurement comes from the Hubble Space Telescope. While for

most telescopes the planet is too small to be seen as anything other than a dot of light,

HST can (just barely) directly measure how big across it is. The measurement isextremely hard, however, even for HST, because even HST distorts light a little bit as it

goes through the telescope, and we needed to be sure that we were measuring the actual

size of the planet, rather than being fooled by distortion. So we waited until Eris was veryclose to a star and then snapped a series of 28 pictures and carefully went back and forth

comparing the star and the planet. In the end, we determined that Eris t is 2400 +/- 100

km across.

The best ever picture from the Hubble Space Telescope, as unimpressive as it is (since

Eris is so so so so so far away) looks like this:
http://www.astro.uni-bonn.de/~bertoldi/ub313/http://www.astro.uni-bonn.de/~bertoldi/ub313/http://www.stsci.edu/http://www.astro.uni-bonn.de/~bertoldi/ub313/http://www.astro.uni-bonn.de/~bertoldi/ub313/http://www.stsci.edu/


5/18


6/18

When we initially guessed how big Erist was, we thought it was likely a bit larger,

because we guessed that it probably reflected the same amount of sunlight as Pluto (about60%). But this new size measurement tells us that the planet reflects considerably more

sunlight than Pluto (86 +/- 7%)!. For more on this see below on what Eris is made out of.

The new HST measurement makes it sound like the previous measurement was "wrong,"

but it was not! All measurements in science are subject to uncertainty, and the group from

Bonn carefully stated what their uncertainty was, just as we have with the newmeasurement. The

What is on the surface of Eris?

We study the composition of distant objects by looking at sunlight reflected off of them.

The sunlight reflected off the surface of the earth, for example, shows distinct signatures

of the oxygen in earth's atmosphere, of photosynthetic plants, and of abundant water,

among other things. We have been using the Gemini Observatory on Mauna Kea, Hawaiito study the light reflected from the surface of Eris, and have found that the dwarf planet

looks remarkably similar to Pluto. A comparison of the two is shown below, where we

show the amount of sunlight reflected in near infrared light. This type of light, justbeyond what is visible to the human eye, is most sensitive to the types of ices expected

on surfaces in the outer solar system.
http://www.gemini.edu/http://www.gemini.edu/


7/18

The plot above compares the amount of infrared sunlight of different colors("wavelength") reflected from the new planet with the amount of sunlight reflected from

Pluto. The dips in the amount of sunlight at 1.15, 1.35, 1.7, and 2.3 um are a

characteristic signature of a surface covered with solid frozen methane (natural gas). BothPluto and Eris show these signatures. At the very low temperatures of Pluto and Eris,

methane, which is in gaseous form on the earth, is frozen solid. The interior of Eris, like

the interior of Pluto, is likely a mixture of rock and ice.

Pluto and the new dwarf planet are not completely identical, however. While Pluto'ssurface is moderately red, the new dwarf planet appears almost white, and while Pluto

has a mottled-looking surface which reflects on average 60% of the sunlight which hits it,

the new planet appears essentially uniform and reflects 86% (+/- 7%) of the light that hitsit. These characteristics were not at all expected. In fact, Eris reflects more sunlight from

its surface than any body in the solar system other than Saturn's moonEnceladus, which

has active geysers continuously coating the surface in fresh frost. We can't think of anysource of heat for Eris that would cause similar geysers. So what is happening?
http://www.solarviews.com/eng/enceladu.htmhttp://www.solarviews.com/eng/enceladu.htmhttp://www.solarviews.com/eng/enceladu.htm


8/18

We think that the bright surface and uniform white coloring of the planet both have the

same cause. Right now the planet is as far away from the sun as it ever gets, and thus ascold as it ever gets. At this distance from the sun even the planet's atmosphere is frozen

solid. (In fact if the earth were brought that far away from the sun its atmosphere would

freeze solid, too!). In 280 years the planet will be the closest it ever gets -- a factor ofalmost 2.6 times closer. The absolute temperature on the planet will rise over the next

280 years by a factor of 1.6 (which is the square root of 2.6). The current temperature of

(a quite cold) 405 degrees below zero will be but a distant memory at this point when thetemperatures will be a balmy 360 degrees below zero. While both of these temperatures

seem frigid beyond imagination, to methane and nitrogen (the likely components of the

atmosphere of the planet), the difference between the two is the difference between

frozen solid and evaporating into the atmosphere.

In this hypothesis, then, Eris is bright and uniform because the atmosphere that it used to

have (280 years ago at its peak) is now frozen solid to the ground, giving a bright shining

coating to whatever type of mottled surface used to be there. The whole atmosphere isnow probably only a few inches thick.

This whole process repeats itself over and over and over with the dwarf planet's orbital

period of 580 years.

For comparison, the relative temperature change on the new planet is equivalent to theearth's average temperature changing from about 60 degrees F to about 360 degrees F

ever 6 months. No other planet in the solar system -- dwarf or otherwise -- goes through

temperature swings nearly as extreme as this!

What is Eris made out of?

While we can only see the surface of the dwarf planet, we have some educated guesses

about the interior. Pluto, we know, has a density about midway between ice and rock,

thus we think that it is made of about half and half ice and rock on the inside. The newplanet, being about the same size and the same surface composition as Pluto, is probably

close to the same. We used to suspect that allobjects out in the Kuiper belt are the same

on the inside but recent measurements suggest a very wide variety! For this reason, we

are quite anxious to measure the actual density of the planet itself. Such a measurement ispossible by measuring the mass of the planet by looking at the way its moon goes around

it and then dividing this mass by the volume (which we know because we know the size).

We need more observations of the moon to accurately determine its orbit, however, so wedon't think we will know the answer until the end of the year.

How was Eris found?

We have been conducting an ongoing survey of the outer solar system using thePalomarQUEST cameraand the Samuel Oschin Telescope atPalomar Observatory in Southern

California. This survey has been operating since the fall of 2001, with the switch to the
http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.htmlhttp://hepwww.physics.yale.edu/quest/palomar.htmlhttp://hepwww.physics.yale.edu/quest/palomar.htmlhttp://hepwww.physics.yale.edu/quest/palomar.htmlhttp://hepwww.physics.yale.edu/quest/palomar.htmlhttp://www.gps.caltech.edu/~chad/quaoar/p48.jpghttp://www.astro.caltech.edu/palomar/http://www.astro.caltech.edu/palomar/http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.htmlhttp://hepwww.physics.yale.edu/quest/palomar.htmlhttp://hepwww.physics.yale.edu/quest/palomar.htmlhttp://www.gps.caltech.edu/~chad/quaoar/p48.jpghttp://www.astro.caltech.edu/palomar/


9/18

QUEST camera happening in the summer of 2003. To date we have found around 80

bright Kuiper belt objects.

To find objects, we take three pictures of a small region of the night sky over three hoursand look for something that moves. The many billions of stars and galaxies visible in the

sky appear stationary, while satellites, planets, asteroids, and comets appear to move. The

image below shows the three frames taken the night of October 21st, 2003 where wefound the new planet. Can you find the moving object?

The area of sky shown here is approximately 0.015% of the amount of sky that we look at

every night, but even though we survey vast regions of the sky per night, it is still going

to take us about 5 years to look at all of the sky visible from Palomar Observatory.

Happily for us (and our families) much of the work is done by computers. The telescope

is robotically controlled and sends its data to Pasadena every morning where it issearched by a bank of 10 computers at Caltech. Each morning the computers find

approximately 100 potentially-moving objects that a human has to look at. The vast

majority are some flaw in the camera and are not real solar system objects, but,

occasionally, as seen above, a real object makes its presence known.


10/18

Because the new dwarf planet is so far away it is moving slower than most of the objects

that we find. It is moving so slowly, in fact, that our computers didn't notice it the firsttime around! We began a special reanalysis a year later to specifically look for very

distant objects. This reanalysis found the new planet at 11:20AM PST on January 5th

2005, almost 1 1/2 years after the initial data were obtained. Note that initial reportssuggested that the discovery date was January 8th. We apologize for the mistake; it was

caused because of the craziness surrounding the first day of announcement. We didn't

have time to check our notes and apparently our memories are not as good as they used tobe.

What is the real name going to be?

this part is obviously out of date. the answer to the question? Eris

When a new object is discovered the International Astronomical Union (IAU) gives it a

temporary designation based on the date it was first seen. Thus 2003 UB313 can bedecoded to tell you that the data from which the object was discovered was obtained inthe second half of October 2003. Next, depending on what the object is, the discoverers

propose a certain type of permanent name.

Interestingly, there are no actual rules for how to name a planet (presumably because no

one expected there to be more). All of the other planets are named for Greek or Romangods, so an obvious suggestion is to attempt to find such a name for the new planet.

Unfortunately, most of the Greek or Roman god names (particularly those associated

with creation, which tend to be the major gods) were used back when the first asteroidswere being discovered. If a name is already taken by an asteroid, the IAU would not

allow that name to be used again. One such particularly apt name would have beenPersephone. In Greek mythology Persephone is the (forcibly abducted) wife of Hades

(Roman Pluto) who spends six months each year underground close to Hades. The newplanet is on an orbit that could be described in similar terms; half of the time it is in the

vicinity of Pluto and half of the time much further away. Sadly, the name Persephone was

used in 1895 as a name for the 399th known asteroid. The perhaps more appropriateRoman version of the name, Proserpina, was used even earlier for the 26th known

asteroid. The same story can be told for almost any other Greek or Roman god of any

consequence. One exception to this name depletion is the Roman god Vulcan (GreekHaphaestus), the god of fire. Astronomers have long reserved that term, however, for a

once hypothetical (now known to be nonexistent) planet closer to the sun than Mercury

(god of fire, near the sun, good name). We would not want to use such a name to describesuch a cold body as our new planet!

Is this object really a planet or a dwarf planet? Is Pluto a planet? What

makes a planet?
http://www.pantheon.org/articles/p/persephone.htmlhttp://www.pantheon.org/articles/p/persephone.htmlhttp://www.pantheon.org/articles/p/persephone.html


11/18

note that all of this is out of date as of August 2006!

Even after all of these years of debate on the subject of whether or not Pluto should be

considered a planet, astronomers appear no closer to agreement. I wrote extensively aboutthis at the time of the discovery of Sedna in March 2004. My thoughts have evolved since

then, so it might be amusing to see what I said 1 1/2 years ago. I have been heavilyinfluenced by writing a scientific review article this summer on the topic of "What is a

planet?" with my colleague Gibor Basri at U.C. Berkeley who I thank for his insights.The main stumbling block in defining planets in our solar system is that, scientifically, it

is quite clear that Pluto should certainly not be put in the same category as the other

planets. Some astronomers have rather desperately attempted to concoct solutions whichkeep Pluto a planet, but none of these are at all satisfactory, as they also require calling

dozens of other objects planets. While people are perhaps prepared to go from 9 to 10

planets when something previously unknown is discovered, it seems unlikely that manypeople would be happy if astronomers suddenly said "we just decided, in fact, that there

are 23 planets, and we decided to let you know right now." There is no good scientific

way to keep Pluto a planet without doing serious disservice to the remainder of the solarsystem.

Culturally, however, the idea that Pluto is a planet is enshrined in a million different

ways, from plastic placemats depicting the solar system that include the nine planets, to

official NASA web sites, to mnemonics that all school children learn to keep the nineplanets straight, to U.S. postage stamps. Our culture has fully embraced the idea that

Pluto is a planet and also fully embraced the idea that things like large asteroids and large

Kuiper belt objects are not planets.

In my view scientists should not be trying to legislate an entirely new definition of the

word "planet." They should be trying to determine what it means. To the vast majority ofsociety, "planet" means those large objects we call Mercury through Pluto. We are then

left with two cultural choices. (1) Draw the line at Pluto and say there are no more

planets; or (2) Draw the line at Pluto and say only things bigger are planets. Both wouldbe culturally acceptable, but to me only the second makes sense for what I think we mean

when we say the word planet. In addition, the second continues to allow the possibility

that exploration will find a few more planets, which is a much more exciting prospectthan that suggested by the first possibility. We don't think the number of planets found by

the current generation of researchers will be large. Maybe one or two more. But we think

that letting future generations still have a shot at planet-finding is nice.

Astronomers tend to dislike this solution as it is clearly non-scientific. The best analogy Ican come up with, though, is with the definition of the word "continent." The word sound

like it should have some scientific definition, but clearly there is no way to construct a

definition that somehow gets the 7 things we call continents to be singled out. Why isEurope called a separate continent? Only because of culture. You will never hear

geologists engaged in a debate about the meaning of the word "continent" though. When

geologists talk about the earth and its land masses they define precisely what they aretalking about; they say "continental crust" or "continental drift" or "continental plates"
http://www.gps.caltech.edu/~mbrown/sedna/index.html#planetshttp://www.gps.caltech.edu/~mbrown/sedna/index.html#planetshttp://www.gps.caltech.edu/~mbrown/sedna/index.html#planets


12/18

but almost never "continent." Astronomers need to learn something from the geologists

here and realize that there are a few things -- like continents and planets -- to which

people have large emotional attachments, and they should not try to quash thatattachment.

Thus, we declare that the new object, with a size larger than Pluto, is indeed a planet. Acultural planet, a historical planet. I will not argue that it is a scientific planet, because

there is no good scientific definition which fits our solar system and our culture, and Ihave decided to let culture win this one. We scientists will continue our debates, but I

hope we are generally ignored.

How was the planetary status be decided?

The above gives my personal view on how to resolve the planetary status. The official

decision will come from the International Astronomical Union. We had hoped for atimely decision but we instead appear to be stuck in committee limbo. Here is the story,

as best I can reconstruct it from the hints and rumors that I hear:

A special committee of the International Astronomical Union (IAU) was charged

with determining "what is a planet."

Sometime around the end of 2005, this committee voted by a narrow margin for

the "pluto and everything bigger" definition, or something close to it.

The exectutive committee of the IAU then decided to ask the Division ofPlanetary Sciences (DPS) of the American Astronomical Society to make a

reccomendation.

The DPS asked their committee to look in to it.

The DPS committee decided to form a special committee.

The IAU decided to that it no longer wanted the DPS to look at the question Nothing happened for a long time

During the summer of 2006 the IAU made a new committee that met for 2 days inParis and came up with the "everything round is a planet" definition

The definition was met with heated opposition at the IAU General Assembly in

Prague

The strict eight planet definition was agreed upon

Whew.

What else is out there?

The last week of July 2005 was an exciting one for the outer solar system. In the course

of two days the existence of three new objects was announced, and each object was

brighter than all of the previously known objects in the Kuiper belt (with the exception ofPluto). With so many bright objects coming out at once it is hard to keep them all

straight. Here is the quick score card:
http://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/eightplanetshttp://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/whatsaplanethttp://www.gps.caltech.edu/~mbrown/eightplanets


13/18

object Eris 2003 EL61 2005 FY9

discoverers Brown, Trujillo,

Rabinowitz

Brown, Trujillo,

Rabinowitz

Brown, Trujillo,

Rabinowitz

size 2400 +/- 100 km (105%

Pluto)

~3/4 Pluto ~3/4 Pluto

brightness 4th brightest Kuiper beltobject (KBO)

3rd brightest KBO 2nd brightest KBO

(note that though we consider Pluto and Eris planets, they are also clearly members of the

Kuiper belt, with Pluto the brightest member)

current distance 97 AU 52 AU 52 AU

(an AU is the distance from the earth to the sun)

orbital period 560 years 285 years 307 years

closest approach to

sun

38 AU 35 AU 39 AU

furthest from sun 97 AU 52 AU 52 AU

tilt of orbit comparedto planets

44 degrees 28 degrees 29 degrees

satellite? yes! yes! (two of them!) no

surface composition Pluto-like water ice Pluto-like

when visible late summer, fall, early

winter

later winter, spring, early summer

Here is where these extremely bright Kuiper belt objects are in the solar system thesedays:
http://www.gps.caltech.edu/~mbrown/2003EL61/index.htmlhttp://www.gps.caltech.edu/~mbrown/planetlila/moon/index.htmlhttp://www.gps.caltech.edu/~mbrown/2003EL61/index.html#moonhttp://www.gps.caltech.edu/~mbrown/2003EL61/index.htmlhttp://www.gps.caltech.edu/~mbrown/planetlila/moon/index.htmlhttp://www.gps.caltech.edu/~mbrown/2003EL61/index.html#moon


14/18

What is the real story about the hasty announcement and the reports of

"hacking"?

In mid-July 2005 short abstracts of scientific talks to be given at a meeting in Septemberbecame available on the web (for example, here). We intended to talk about the object

now known as 2003 EL61, which we had discovered around Christmas of 2004, and the

abstracts were designed to whet the appetite of the scientists who were attending themeeting. In these abstracts we call the object a name that our software automatically

assigned, K40506A (the first Kuiper belt object we discovered in data from 2004/05/06,

May 6th). Using this name turns out to have been a very bad idea on our part!Unbeknownst to us, some of the telescopes that we had been using to study this object

kept open records of who has been observing, where they have been observing, and what

they have been observing (these detailed records have since been removed from the web).

A two-second Google search of "K40506A" immediately reveals one of these observingrecords. A little playing around with web addresses then reveals even more records not

initially Googleable. Ouch. Bad news for us. From the moment the abstracts became

public anyone on the planet with a web connection, and a little curiosity about this"K40506A" object, and a knowledge of orbital dynamics could have found out where it

was. Anyone on the planet with even a modest-sized telescope could then go find the

object and claim a discovery as their own.
http://www.aas.org/publications/baas/v37n3/dps2005/786.htmhttp://www.aas.org/publications/baas/v37n3/dps2005/786.htm


15/18

According to our web server logs, these observing logs were accessed on July 26, 2005

by a computer at the Instituto de Astrofisica in Spain. Less than two days after this

computer accessed the observing logs, the same computer was used to send emailofficially claiming the discovery by P. Santos-Sanz and J.-L. Ortiz at the Instituto de

Astrofisica (see detailed timeline here). At the time of the announcement we truly

believed that they had no prior knowledge that we had been observing the object, and wetruly believed that they had not used our data to make the announcement of the discovery,

but other people found the coincidence suspicious.. Shortly after their announcement,

however, we realized that all of our observing records -- including those about what isnow known as 2003 UB313, the tenth planet -- were unexpectedly public, and made the

decision to prematurely announce the discovery of 2003 UB313 that same afternoon by a

press conference. We were unhappy about having to forgo normal scientific protocol and

announce the discovery with no corresponding scientific paper, but under thecircumstances we felt we had no choice.

It is worth asking: if the observing records were on a publicly accessible web site, is it

wrong to look at them? The obvious answer is that there is nothing wrong with looking atinformation on any publicly accessible web site, just as there is nothing wrong withlooking at books in a library. But the standards of scientific ethics are also clear: any

information used from another source must be acknowledged and cited. One is not

allowed to go to a library, find out about a discovery in a book, and then claim thatdiscovery as your own with no mention of having read it in a book. One is not even

allowed to first make a discovery and then go to the library and realize that someone else

independently made the same discovery and then not acknowledge what you learned inthe library. Such actions would be considered scientifically dishonesty. It is not clear

from the timeline precisely what Ortiz and Santos-Sanz knew or how they used the web-

based records. They were required by the standards of science, however, to acknowledge

their use of our web-based records if they accessed them. The director of the IAA, Dr.Jose Carlos del Toro Iniesta has promised to investigate what precisely happened. We

have confidence in Dr. del Toro Iniesta to clarify the situation and determine the

appropriate actions.

Some have commented that the real fault here was our own for keeping the objects

"secret." We are saddened by anti-scientific statements like these, and have already

written extensively on why this rather bizarre accusation is spuriousbelow. The

community of scientists condemns scientists who announce their results publicly beforepublishing scientific papers. Regardless of the number of times these bizarre accusations

are repeated, we will continue at all times to adhere to accepted scientific protocol.

Why does it take so long to announce these discoveries?

Soon after the announcement of the discovery of the new planet the suggestion slowlymade its way around the internet that we, the discoverers, were somehow violating long

standing scientific standards by keeping the existence of the planet "secret" for so long.
http://www.gps.caltech.edu/~mbrown/planetlila/ortizhttp://www.gps.caltech.edu/~mbrown/planetlila/#discoveryhttp://www.gps.caltech.edu/~mbrown/planetlila/#discoveryhttp://www.gps.caltech.edu/~mbrown/planetlila/ortizhttp://www.gps.caltech.edu/~mbrown/planetlila/#discovery


16/18

This suggestion seemed so bizarre to us that we paid no attention at first, but, as with

many things on the internet, it has been repeated enough times even reasonable people

are starting to believe it. We would like to quickly dispell this odd misconception that nocredible scientist would hold.

One of the things that is so strange about this allegation is that it should also be made ofevery single scientific result that is published in a reputable scientific journal. In all such

cases, scientists make discoveries, they verify their discoveries, they carefully document

their discoveries, and they submit papers to scientific journals. What they don'tdo ismake discoveries and immediately hold press conferences to announce them (one need

only think back to the cold fusion days to remember how thoroughly the scientific

community condemns such behavior). Good science is a careful and deliberate process.

The time from discovery to announcement in a scientific paper can be a couple of years.For all of our past discoveries, we have described the objects in scientific papers before

publicly announcing the objects' existence, and we have made that announcement in

under nine months. These papers allow other astronomers to verify, confirm, and critique

the analysis we have done. Sadly, because we were forced to announce 2003 UB313prematurely, we have still yet to complete the scientific paper describing this object ( it isnow finally complete!see below). We find this situation scientifically embarrassing andapologize to our colleagues who are reduced to learning about this new object from

reading reports in the press. We are hard at work on this scientific paper, but, as we said

above, good science is a careful and deliberate process and we are not yet through with

our analysis. Our intent in all cases is to go from discovery to announcement in undernine months. We think that is a pretty fast pace.

One could object to the above by noting that the existence of these objects is never indoubt, so why not just announce the existence immediately upon discovery and continue

observing to learn more? This way other astronomers could also study the new object.

There are two reasons we don't do this. First, we have dedicated a substantial part of ourcareers to this surveyprecisely so that we can discover and have the first crack at

studying the large objects in the outer solar system. The discovery itself contains little of

scientific interest. Almost all of the science that we are interested in doing comes fromstudying the object in detail afterdiscovery. Announcing the existence of the objects and

letting other astronomers get the first detailed observations of these objects would ruin

the entire scientific point of spending so much effort on our survey. Some have argued

that doing things this way "harms science" by not letting others make observations of theobjects that we find. It is difficult to understand how a nine month delay in studying an

object that no one would even know existed otherwise is in any way harmful to science!

Many other types of astronomical surveys are done for precisely the same reasons.

Astronomers survey the skies looking for ever higher redshift galaxies. When they find

them they study them and write a scientific paper. When the paper comes out otherastronomers learn of the distant galaxy and they too study it. Other astronomers cull large

databases such as the 2MASS infrared survey to find rare objects like brown dwarves.

When they find them they study them and write a scientific paper. When the paper comes

out other astronomers learn of the brown dwarves and they study them in perhaps
http://www.gps.caltech.edu/~mbrown/planetlila/#paperhttp://www.gps.caltech.edu/~mbrown/planetlila/#paper


17/18

different ways. Still other astronomers look around nearby stars for the elusive signs of

directly detectable extrasolar planets. When they find one they study it and write a

scientific paper..... You get the point. This is the way that the entire field of astronomy --and probably all of science -- works. It's a very effective system; people who put in the

tremendous effort to find these rare objects are rewarded with getting to be the first to

study them scientifically. Astronomers who are unwilling or unable to put in the effort tosearch for the objects still get to study them after a small delay.

There is a second reason that we don't announce objects immediately, and that is becausewe feel a responsibility not just to our scientific colleagues but to the public. We know

that these large objects that keep being found are likely to be the result of intensive

interest by the public, and we would like to have the story as complete as possible before

making an announcement. Consider, for example, the instantaneous Ortiz et al.announcement of the existence of 2003 EL61. Headlines in places like the BBC web site

breathlessly exclaimed "new object may be twice the size of Pluto." But even at the time

we knew that 2003 EL61 had a satellite and was only 30% the mass of Pluto. We quickly

got the truth out, but just barely. Sadly, other interesting aspects of 2003 EL61 also gotlost in the shuffle. No one got to hear that it rotates every 4 hours, faster than anything

else known in the Kuiper belt. Or how that fast rotation causes it to be shaped like a cigar.Or how we use the existence of the satellite to calculate the mass. All of these are

interesting things that would have let the public learn a bit more about the mysteries of

physics and of the solar system. In the press you get one chance to tell the story. In the

case of the instantaneous announcement of 2003 EL61 the story was simply "there is abig object out there." We are saddened by the lost opportunity to tell a richer scientific

story and to have the public listen for just one day to a tale that included a bit of

astronomy, a bit of physics, and a bit of detective story.

Given that we do precisely what other astronomers do and that we are actually very

prompt about making announcements, where did the crazy ideas that we should beannouncing objects instantly come from? Interestingly, there is one area of astronomy in

which instantaneous announcement is both expected and beneficial to all. In the study of

rare, quickly changing objects, such as supernovae, gamma ray bursts, comets, and nearearth asteroids, astronomers quickly disseminate their results so that as many people as

possible can study the phenomenon before it disappears or changes completely. No one

discovers a comet and keeps it to himself to study, because by the time the study was

done the comet would be gone and no one else could study it ever again. The peopleinitially suggesting that we were wrong to not announce our objects instantly are, for the

most part, a small group of amateur astronomers who are familiar with comet and near

earth asteroid observation protocols. We can only assume that this familiarity led them totheir misconceptions. Kuiper belt objects are not quickly changing phenomena.

Astronomers will be intensively studying Eris for a long time to come.

We hope to discover a few more large objects in the outer solar system. When we do, we

will do everything we can to learn as much as possible about them before we make their

existence public, and we will try to make the announcement as complete and

scientifically and publicly interesting as possible. We will take the chance -- as all


18/18

scientists do -- that by taking the time to do the scientific job correctly someone else may

beat us to the announcement, and if they do we will congratulate them heartily.

The scientific paper describing the discovery is finally done!

As described in detail elsewhere, we were forced to announce the existence of Eris beforewe had finished a scientific paper describing the discovery. While announcingdiscoveries via press releases with no scientific paper is generally frowned upon by

scientists (including us) our colleagues have been understanding of the unusual

circumstances under which this happened. The scientific paper describing the discoveryhas just been submitted to the Astrophysical Journal. If you are curious what one of these

papers looks like you can read the entire text. Now that the paper has been submitted to

the journal, the journal will send it out for peer-review, where another scientist willcarefully and critically read what we have read and help decide if the paper meets

accepted scientific standards. In almost all cases, the reviewer will suggest at least some

changes to the manuscript before the paper is finally accepted. This process helps ensure

that published scientific papers are as accurate and complete as possible.

As of now the review process is complete and the revised paper is published in the

December 10th 2005 issue of the Astrophysical Journal Letters.
http://www.gps.caltech.edu/~mbrown/papers/ps/xena.pdfhttp://www.gps.caltech.edu/~mbrown/papers/ps/xena.pdf

Documents

The Discovery of 2003 UB313 Eris