ScienceCasts: Smallest Terrestrial Planet?

Visit http://science.nasa.gov/science-news/science-at-nasa/2011/09dec_vestaplanet/ for more.

NASA's Dawn probe, now orbiting Vesta in the asteroid belt, has found some surprising things on the giant asteroid--things that have prompted one researcher to declare Vesta "the smallest terrestrial planet."

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Science & Technology

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• ScienceCasts
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• Science Mission Directorate
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• asteroid
• dwarf planet
• Dawn
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• protoplanet

[lordedvard8]

Pluto was once a planet too...

[VladiSSius]

i like NASA...

[Tounushi]

Dwarf planet: differentiated, spherical body.

Vesta may be differentiated, but it is by no means spherical. It's more like a big potato.

[HostileNegotiator]

@Pyrolonn Cool, thanks for clarifying :) I can't wait to learn about the super sized Earth like planet they discovered. Keppler 22b I think is its name.

[Skaarjguy]

If the IAU calls Vesta a Dwarf Planet then that means they'll be violating their own rules of planethood. If anything it should be a new class of asteroid, the only one of its kind besides Ceres. If that means calling it something silly like Vestoid then so be it.

[Pyrolonn]

@HostileNegotiator Actually, Pluto was downgraded to a "dwarf planet" (not asteroid), which is what the NASA investigator is claiming Vesta to be. (Pluto was given a minor planet number but still gets the dwarf planet status) Ceres already has dwarf planet status.

[HostileNegotiator]

I admit I was upset when Pluto was downgraded to a planetiod. But in the aftermath I have realized there are classes of planets as we discover more and more. I have a feeling planets like Pluto will once again join our planetary family but defined in a class. Wow. Even science is classist.

[Tiggification]

This is a wonderful opportunity! So glad it was successful thus far. Any knowledge we can gain is tremendous.

As for categorizing Vesta, to me the IAU are goofballs- no telling what they'll decide to label Vesta as. The decisions of a few scientists over the many, sigh. Poor Pluto, would have at least waited till New Horizons got there :-) but names and labels can be trivial.

[jasleil]

@laurele861 0.o. Wow. Still I would want to know what will Vesta be at the end.

[laurele861]

@THE16THPHANTOM That's not exactly true. The astronomy community remains divided about the issue of planet definition. If you study astronomy and join an astronomy club, you too can have a voice in this discussion.

[laurele861]

@Hagenfels No, it was not necessary to "draw a line" about what we call planets. We don't do that with stars and galaxies to keep the number small. It makes no sense to arbitrarily say that dwarf planets, which have structure, composition and processes that planets have, are not planets at all. Instead, we should add dwarf planet as a subcategory of the broader term planet. Eventually, as understand exoplanets more, there will likely be many more subcategories.

[laurele861]

@jasleil Eris is in the outer part of the Kuiper Belt known as the Scattered disk. Objects there have much more inclined orbits. As for textbooks, they will have to adapt, just like we will, to a universe with billions of planets. Just describe each subtype of planet and its characteristics; a list of solar system planets with their correct subcategories can be placed in a table on one page. If a Kuiper Belt object is large enough to be spherical, it's a planet.