New Dwarf Planet!

CCSSC.org ^ | 7/14/08

[LibWhacker]

Image credit: compiled from NASA public images

At times, people still express bemusement, or confusion, that Pluto was reclassified as a "dwarf planet", after having been considered a full-fledged planet for the better part of a century. One thing I always point out to them is that we're discovering more and more roughly Pluto-sized bodies. If we call them all planets, the list of planets would rapidly grow unmanageable! (Do you want to memorize the names of 20 planets? How about 80?)

Today the list just got bumped up by one. Meet Makemake, the first body in our solar system to be classified as a dwarf planet since the 2006 IAU decision that established the category of dwarf planets in the first place. When the IAU made its ruling, they put three worlds in that category: Pluto, Ceres, and Eris. Now Makemake makes the fourth.

Follow up:

It's also the third world to be classified as plutoid - a dwarf planet beyond Neptune's orbit. Pluto and Eris (and now Makemake) are plutoids; Ceres, which orbits in the asteroid belt, isn't.

The discoverer of Makemake, Mike Brown, is the same guy who discovered Eris. (That discovery triggered a lot of the most recent discussion of what makes a planet, so in a way, Dr. Brown's discoveries led to the whole dwarf planet issue in the first place.) He has a fascinating discussion of why he proposed the name Makemake for this world. The name was confirmed by the IAU at the same time as the world was classified as dwarf planet and plutoid.

So now the planetary record stands thusly:

• Major planets (terrestrial): Mercury, Venus, Earth, Mars
• Major planets (jovian): Jupiter, Saturn, Uranus, Neptune

• Dwarf planet (asteroid, or terrestrial): Ceres
• Dwarf planets (plutoid): Pluto, Eris, Makemake
• Total score: 8 major planets, 4 dwarf planets

You can keep track with this official IAU list.

Expect this list to expand, however. There are many bodies that stand a good chance of being added to the dwarf planet list. In most cases, it's a matter of confirming that these bodies are actually more or less spherical - that they're large enough for their own gravity to have pulled them into a sphere. (Geek speak for this: hydrostatic equilibrium.) Some future candidates:

• Possible dwarf planets (asteroid, or terrestrial): Vesta, Pallas (unlikely), Hygiea
• Possible dwarf planets (plutoid): 2003 EL61 ("Santa"), Sedna, Quaoar, Orcus, Ixion, and 2002 AW197 ("No cute nickname"), plus over 70 smaller candidates currently being investigated.

That's not counting Charon, which is currently listed as a moon of Pluto. Physically speaking, though, that's questionable, since it would be more accurate to say that Pluto and Charon both orbit around their common center of mass, which lies somewhere between them. I personally think that Pluto and Charon should be considered a "double dwarf planet"...

[Seruzawa]

So, when are they finally going to find Nibiru? It’s gotta be close. Obama is obviously from there.

[Tanniker Smith]

Planets have Roman names. But I guess that they can get around this by claiming it's not a planet.

Then again, the moons all have strange rules. If I remember correctly, the moons of Jupiter have to end with a specific letter. It's something like the moons ending with "a" orbit one way and the ones ending in "o" orbit the other way.

so is it Make - Make or is it Mah Key Mah Key ??

[LibWhacker]

OMG, you're right, thanks!

So for more than three years it's been variously called 2005 FY9, Easterbunny, and K50331A, but didn't get its permanent name and dwarf planet designation until a week ago.

When we think of things moving at astronomical speeds, at least I tend to think of them as moving around really fast. But this does not apply to astronomers themselves.

[Sawdring]

We need to start nudging these dwarf planets into orbits that intersect with Mars. We could find a nice water dwarf planet and one made of of iron and collide them into Mars' surface to raise its mass and hopefully jump starts its core to increase its magnetic field. Then we combine Deimos and Phobos and add some more mass and set the single moon in an orbit that will stabilize Mars' seasons. With a 20,000 year time frame to cool things down, I think it is entirely possible to make Mars more habitable.

[BigCinBigD]

Hello! Pizza Palace..This is..Er Willie Tanner, We need 23 large meat pizzas. Make that extra meat, we're celebration. They found Melmac! HA!

[NewJerseyJoe]

> Dwarf Planets

VERY politically incorrect. The preferred term is "little planets."

[Sacajaweau]

I have an old geography book. It shows and names more planets than what we learned in the 60’s. It also shows a big warm spot in the Pacific.

[LibWhacker]

Nibiru, huh? I had to look that up, thanks! Anunnakians must look something like the Ferengi, big-eared, dopey looking things.

[yarddog]

I had never thought about it but they all are Roman names except for Uranus which is Greek.

[Mr_Moonlight]

> Dwarf Planets

VERY politically incorrect. The preferred term is "little planets."

Oh my, what are we doing here? Next thing we'll see is "Planet Tossing Competition" on ESPN !

[NTHockey]

>>Don’t call them Dwarf Planets. They prefer to be called Little Planets.

Let’s have some consideration around here : )<<

How insensitive of you! They are size-challenged planets.

And why isn’t Dr. Brown working on the flux capacitor?

Pluto for Plutonium, Neptune for Neptunium, ... Makemake for Makemakeium? Doesn’t quite have the same ring to it?

[CaliGangsta]

Al Gore was right. Clearly this planet was created by global warming.

[humblegunner]

New Dwarf Planet!

I bet I could find a girlfriend for Winky there!

[Conspiracy Guy]

I apologize for my insenstivity.

I am so ashamed of me.

[Lancey Howard]

I wonder if God is into “little planet bowling”?

[Allegra]

I bet I could find a girlfriend for Winky there!

She'd have to look kind of like a monkey.

[Mr Ramsbotham]

I had never thought about it but they all are Roman names except for Uranus which is Greek.

That's because Greeks have a special interest in Uranus.

[Conspiracy Guy]

When the time comes.

[RightWingTeen]

Did we humans find VULCAN yet??

[Verginius Rufus]

The 4 largest moons (the ones first seen by Galileo) are Io, Europa, Ganymede, and Callisto—so 3 different final vowels for 4 moons. The largest moons revolve counterclockwise, but a lot of the smaller ones revolve clockwise (which may indicate they are captured asteroids).