From its distance from the sun, to how it helped change the definition of a planet,
and more!
Join me as I show you Eris: Facts and History!
8.
What Is Eris?
Depending on your familiarity with our solar system, you may or may not know about Eris,
and for good reason based on its location and how it relates to other planets and celestial
objects in the system.
In short, Eris is one of the largest known dwarf planets in our solar system.
For those who don't know, a Dwarf Planet is one that has the size and shape of a planet
but fails to meet certain technical qualifications to be considered a full planet.
Eris is about the same size as Pluto, but is three times farther from the Sun.
Making it something on the very edges of our solar system.
In fact, outside of some comets that have been discovered and a "unique object" from
2018, the two are the most distant known objects in our solar system.
Eris first appeared to be larger than Pluto.
This triggered a debate in the scientific community that led to the International Astronomical
Union's decision in 2006 to clarify the definition of a planet.
Pluto, Eris and other similar objects are now classified as dwarf planets.
Originally designated 2003 UB313 (and nicknamed for the television warrior Xena by its discovery
team), Eris is named for the ancient Greek goddess of discord and strife.
The name fits since it remains at the center of a scientific debate about the definition
of a planet.
7.
The Discovery Of Eris Given all we just told you, the discovery
of this dwarf planet is really significant.
Eris was discovered by the team of Mike Brown, Chad Trujillo, and David Rabinowitz on January
5, 2005, from images taken in October of 2003.
The discovery was announced in July 2005, the same day as Makemake and two days after
Haumea (two other dwarf planets), due in part to events that would later lead to controversy
about Haumea.
The search team had been systematically scanning for large outer Solar System bodies for several
years, and had been involved in the discovery of several other large TNOs, including 50000
Quaoar, 90482 Orcus, and 90377 Sedna.
The reason that Eris wasn't discovered right away via the images in 2003 was very simple,
Eris was moving so slowly that scientists weren't able to detect it.
The team at the Palomar Observatory had automatic image-searching software that excluded all
objects moving at less than 1.5 arcseconds per hour to reduce the number of false positives
returned.
When Sedna was discovered in 2003, it was moving at 1.75 arcsec/h, and in light of that
the team reanalyzed their old data with a lower limit on the angular motion, sorting
through the previously excluded images by eye.
In January 2005, the re-analysis revealed Eris's slow motion against the background
stars.
Thus leading to its true discovery.
After that, the team dedicated itself to learning more about the soon-to-be-named dwarf planet,
mainly learning what kind of orbit it had, and eventually learning the discovery that
it had a moon within its orbit.
6.
The Xena Name I'm sure some of you out there were a bit
curious as to why a scientific team would nickname a planet "Xena" after the legendary
TV show featuring Lucy Lawless.
Granted, that's not the name the Dwarf Planet has now, but the story behind this nickname
is honestly rather unique to our solar system.
Due to uncertainty over whether the object would be classified as a planet or a minor
planet, because different nomenclature procedures apply to these different classes of objects
(which would lead to the demoting of Pluto not long after Eris' discovery and classification),
the decision on what to name the object had to wait until after the August 24, 2006 IAU
ruling.
As a result, for a time the object became known to the wider public as Xena.
But why that one?
"Xena" was an informal name used internally by the discovery team.
It was inspired by the title character of the television series Xena: Warrior Princess.
The discovery team had reportedly saved the nickname "Xena" for the first body they discovered
that was larger than Pluto.
According to Mike Brown, who was part of the team that discovered the dwarf planet:
"We chose it since it started with an X (planet "X"), it sounds mythological (OK, so it's
TV mythology, but Pluto is named after a cartoon, right?), and (this part is actually true)
we've been working to get more female deities out there (e.g. Sedna).
Also, at the time, the TV show was still on TV, which shows you how long we've been searching!"
He noted that the name was honestly a bit of a joke to have fun with it because the
team figured that a true name for the object would come relatively quickly, but it didn't.
The process was delayed because of the classification issue, and thus, Xena stuck for a long time.
As for how that name got stuck with the public at large, you can blame the press for that:
" One reporter [Ken Chang] called me up from The New York Times who happened to have been
a friend of mine from college, [and] I was a little less guarded with him than I am with
the normal press.
He asked me, "What's the name you guys proposed?" and I said, "Well, I'm not going to tell."
And he said, "Well, what do you guys call it when you're just talking amongst yourselves?"
... As far as I remember this was the only time I told anybody this in the press, and
then it got everywhere, which I only sorta felt bad about—I kinda like the name."
While obviously Eris would take hold as the true name, the notion that Xena as the dwarf
planet's title held on for a while is a pretty special thing, and you can bet that the show
and its stars were happy to have made an impact of such a nature that they had a planet named
after them...for a while, anyway.
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5.
The Classification Debate Eris is a trans-Neptunian dwarf planet (plutoid).
Its orbital characteristics more specifically categorize it as a scattered-disk object (SDO),
or a TNO that has been "scattered" from the Kuiper belt into more-distant and unusual
orbits following gravitational interactions with Neptune as the Solar System was forming.
Although its high orbital inclination is unusual among the known SDOs, theoretical models suggest
that objects that were originally near the inner edge of the Kuiper belt were scattered
into orbits with higher inclinations than objects from the outer belt.
Because it was initially thought to be larger than Pluto (Pluto is a bit larger in volume
it would later be discovered), it was described as the "tenth planet" by NASA and in media
reports of its discovery.
In response to the uncertainty over its status, and because of ongoing debate over whether
Pluto should be classified as a planet, the IAU delegated a group of astronomers to develop
a sufficiently precise definition of the term planet to decide the issue.
The irony of this is many-fold, not the least of which is that for many decades the "definition"
of a planet was very loose, which was why Pluto was named, and held as, a planet for
so long.
There are also those who say that the new classification system isn't "true" but is
just an arbitrary decision made by some and not by all.
This new system was announced as the IAU's Definition of a Planet in the Solar System,
adopted on August 24, 2006.
At this time, both Eris and Pluto were classified as dwarf planets, a category distinct from
the new definition of planet.
Mike Brown (who helped discover Eris as we noted earlier) has since stated his approval
of this classification.
The IAU subsequently added it to its Minor Planet Catalogue.
There are some who choose to ignore this classification based solely on how it's not fair to Pluto,
and to those who taught astronomy and declared it a planet.
As such, some refuse to label it as a dwarf planet.
It's very curious how a simple discovery can upend everything you thought you knew about
something.
4.
Orbit Eris has an orbital period of 559 years.
Its maximum possible distance from the Sun (aphelion) is 97.65 AU, and its closest (perihelion)
is 37.91 AU.
It came to perihelion between 1698 and 1699, to aphelion around 1977, and will return to
perihelion around 2256 to 2258.
Unlike the eight planets, whose orbits all lie roughly in the same plane as the Earth's,
Eris's orbit is highly inclined: It is tilted at an angle of about 44 degrees to the ecliptic.
When discovered, Eris and its moon were the most distant known objects in the Solar System,
apart from long-period comets and space probes.
It retained this distinction until the discovery of 2018 VG18 in 2018.
Eris's orbit is highly eccentric, and brings Eris to within 37.9 AU of the Sun, a typical
perihelion for scattered objects.
This is within the orbit of Pluto, but still safe from direct interaction with Neptune
(~37 AU).
Pluto, on the other hand, like other plutinos, follows a less inclined and less eccentric
orbit and, protected by orbital resonance, can cross Neptune's orbit.
In about 800 years, Eris will be closer to the Sun than Pluto for some time.
Because of the high inclination of its orbit, Eris passes through only a few constellations
of the traditional Zodiac; it is now in the constellation Cetus.
It was in Sculptor from 1876 until 1929 and Phoenix from roughly 1840 until 1875.
In 2036 it will enter Pisces and stay there until 2065, when it will enter Aries.
It will then move into the northern sky, entering Perseus in 2128 and Camelopardalis (where
it will reach its northernmost declination) in 2173.
3.
Formation and Structure Dwarf planet Eris is a member of a group of
objects that orbit in a disc-like zone beyond the orbit of Neptune called the Kuiper Belt.
This distant realm is populated with thousands of miniature icy worlds, which formed early
in the history of our solar system about 4.5 billion years ago.
These icy, rocky bodies are called Kuiper Belt objects, transneptunian objects, or plutoids.
The irony though is that as we mentioned earlier, Eris is WAY out there in the solar system.
It's one of the farthest objects from the sun, and unlike many in the Kuiper Belt it's
not surrounded by a lot of other objects, which is part of the reason why it took so
long to discover.
So the question is, if it formed very much like the other objects in the belt, how was
it formed so far away?
We know that the suns gravity has an enormous range, as proven by the dwarf planets orbit
for if it wasn't in range of the gravity it wouldn't be orbiting the star, but how was
it able to make an object of that size that's so far away?
Which brings us to the mystery of its structure.
Because of its enormous distance from us, we honestly don't know much about what makes
the dwarf planet tick in terms of its rock structure, its elements that make it up, etc.
Now, yes, we can guess some things based on pictures, Eris most likely has a rocky surface
similar to Pluto (which would add up given their distance from the sun and the particles
and elements that likely formed them).
Also, scientists think surface temperatures vary from about -359 degrees Fahrenheit (-217
degrees Celsius) to -405 degrees Fahrenheit (-243 degrees Celsius).
Which obviously would make it a very cold and frozen world, again, just like Pluto.
But the inner workings of the planet?
We have little to no clue as to how that is.
And unless we get a craft to where it is, that's not likely to change.
Could we get something there one day?
Absolutely!
But the question is one of when, and how long it'll take to not just get there, but get
meaningful data from it.
2.
Its Moon Eris has a very small moon called Dysnomia.
Dysnomia has a nearly circular orbit lasting about 16 days.
This moon is named after Eris' daughter, the demon goddess of lawlessness.
A very curious pairing of names, and yet somewhat accurate given what these celestial objects
have done in terms of their impact on the solar system.
Dysnomia and other small moons around planets and dwarf planets allow astronomers to calculate
the mass of the parent body.
Dysnomia played a role in determining how comparable Pluto and Eris are to each other.
1.
Atmosphere The dwarf planet is often so far from the
Sun that its atmosphere collapses and freezes, falling to the surface as snow.
As it gets closest to the Sun in its faraway orbit, the atmosphere thaws.
Which is something you wouldn't expect from a planet or dwarf planet at all, further showing
how location in the solar system is infinitely important.
If you're curious about the Magnetosphere, there is no evidence that it has one, but
there also isn't any evidence that it doesn't have one.
This is another case where its distance harms how much we can learn about it as a whole.
Thanks for watching everyone!
What did you think of this look at Eris and everything that is associated with it in terms
of facts and history?
Which of these facts did you find the most fascinating?
Do you think we'll ever get the chance to learn more about Eris?
Let me know in the comments below, be sure to subscribe, and I'll see you next time on
the channel!