Planet Mercury Has Shrunk More Than Thought

sciencehabit writes "Measuring just 4880 kilometers across, Mercury is a small world. The planet became slightly smaller as its interior cooled, which caused Mercury to shrink, buckling its surface and creating numerous cliffs and ridges. Now, after studying 5934 of these features, researchers report online today in Nature Geoscience that Mercury's contraction was much greater than previously thought: During the past 4 billion years, the planet's diameter decreased by 7 to 14 kilometers. The greater estimate of shrinkage accords with models that predict how much a rocky planet should contract as its interior cools; the new work may also lend insight into the evolution of extrasolar planets that, like Mercury and unlike Earth, lack any moving continents."

Someone left it in the dryer too long..

[toonces33]

Easy mistake to make.

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[gargleblast]

This will soon be the text of a new motivational poster: Mercury: Think. Or Shrink.

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[Dragonslicer]

So can we look forward to pre-shrunk planets?

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[JWSmythe]

Earth is a toxic waste repository for the dominant invasive species.

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[Ferrofluid]

You're thinking of Pluto.

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[Anonymous Coward]

You're thinking of Pluto.

No, Uranus.

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[Hussam Al-Tayeb]

nope, decreased by 14km (not TO 14km). It i still around twice the size of pluto.

Re:Whoa, tiny planet!!

[sidyan]

Mercury [wikipedia.org]'s diameter is 2.11 times that of 134340 Pluto [wikipedia.org], but its mass is 25.3 that of the puny dwarf planet.

Discounting metallic hydrogen on Jupiter and Saturn, Mercury's definately the most Metal planet in the solar system.

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[mjwx]

Mercury [wikipedia.org]'s diameter is 2.11 times that of 134340 Pluto [wikipedia.org], but its mass is 25.3 that of the puny dwarf planet.

Discounting metallic hydrogen on Jupiter and Saturn, Mercury's definately the most Metal planet in the solar system.

Of course it would be, you don't ever hear of a metal band with some pansy ass name like Jupiter.

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[mister_playboy]

Of course it would be, you don't ever hear of a metal band with some pansy ass name like Jupiter.

Heh... in fact...

http://visualioner.files.wordp... [wordpress.com]

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[operagost]

Thanks, Dr. Tyson, but we don't need Pluto's minor planet designation any more than we need Ceres'. It's pretty friggin' famous.

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[mythosaz]

Mercury's definately the most Metal planet in the solar system.

ROCK ON!

|nn|/

Re:Whoa, tiny planet!! Metal Planet

[bbsalem]

So its average density must be high, and the number of pits and caves on its surface and the collapse features say that volitile elements have been cooked out of what is left. Maybe someone in the know can tell if there is much S on the surface.

I'm sure that long after we have looked at differentiated planetessimals from the asteroid belt for heavy metals, imagine finding double the reserves of rare Iron group metals, or many times the amount of Au, Pt, Zr, Rh, Pd, Ir, Ti, Zr, out there than on the eart

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[EvilSS]

nope, decreased by 14km (not TO 14km). It i still around twice the size of pluto.

So it's safe from being plutoed [theregister.co.uk] by NDT [wikipedia.org].... for now.

Re: Whoa, tiny planet!!

[kyjellyfish]

The leading theory says that Mercury survived an early solar system collision, like the glancing blow that a protoplanet had with theEarth, which spawned the Moon. But Mercury's collision was more head-on, which resulted in the majority of it's crust and mantle being blown away. Thus, Mercury's makeup is primarily iron/nickle, like Earth's core.

Shrinkage sucks.

[Anonymous Coward]

It's the girth, not the length that matters.

Shrinkage

[Tippler]

The shrinkage of a body in response to cooling was experimentally derived by Dr. Costanza in the 90's.

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[banda]

...like a frightened turtle

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[ArcadeMan]

Unfortunately, specialists such as Dr. Benes are not aware of all the research done in the field of shrinkage and continue to publish papers that are crucially missing this important information.

Laugh

[koan]

Mercury is trying to tell all the other planets it's shrinkage but they know better.

Obligatory penis joke aside, I'm surprised to hear it has "cooled" with it's greatest distance from the Sun being a mere 69,816,900 km.

Comment removed

[account_deleted]

Comment removed based on user account deletion

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[Anonymous Coward]

I would think the lack of atmosphere would prevent losses rather then insulate because a vacuum provides the best thermal insulation. If you look into building space craft you'll see removing heat is one of the primary challenges along with balancing the heat from the sun side and the shadow side. The reason why the shadow side of Mercury is freezing cold is because it barely rotates around it's axis it's day is equal to 58+ days on earth. It has plenty of time to lose heat due through radiation. Also i

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[asylumx]

I think you're talking out of Uranus.

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[Anonymous Coward]

Lets turn this around, how would an atmosphere promote loss? Where does that heat go? It still has to deal with vacuum insulation, just now a few kilometers higher than before. You can have evaporative cooling of some sort, where heat blows off part of the atmosphere, but then it wouldn't last very long without a source on the surface. Otherwise, it would help trap heat, which still has to go into the vacuum of space to fully leave the planet.

Mercury may be shrinking...

[Anonymous Coward]

...but Uranus is expanding!

Of course

[Culture20]

Space is cold!

warning: bad pun inbound

[gman003]

Ball-shrivelingly cold, as it turns out.

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[ArcadeMan]

It's only common knowledge if you are male. Some females, however, did learn about shrinkage from a TV show called "Seinfeld".

saw this one coming?

[slashmydots]

In other news, your mother's diameter has expanded by 2km.

... but IS IT STILL A PLANET?

[Arancaytar]

That's the important question.

We don't want a repeat of the Pluto incident. The solar system is already 11% gone, who knows how much we'll lose.

Sing with me!

[funwithBSD]

It's a small world after all...

That's funny

[DougDot]

I thought cold caused shrinkage.