Planet Mercury Is Shrinking Rapidly, Has Lost 7 Kilometers in Radius

[Rhykker]

Planet Mercury Is Shrinking Rapidly, Has Lost 7 Kilometers in Radius

New findings indicate that Mercury has shrunk by up to seven kilometers in radius over the past four billion years. Previous estimates led researchers to believe it had only shrunk by one or two kilometers.

The qualifier "rapidly" may be a little misleading when dealing with geologic time scales, but the planet closest to the Sun has indeed been shrinking at a rate several times greater than previously believed. Over the past four billion years, Mercury has shrunk by up to seven kilometers in radius, according to new evidence gathered by NASA's MESSENGER spacecraft.

The new finding was published in the journal Nature Geoscience Sunday, March 16 and has actually helped resolve a discrepancy in theory and observation. Previous estimates based on Mariner 10 data suggested that Mercury had only lost one to two kilometers, which didn't match up with models of the planet's formation and aging.

"With MESSENGER, we have now obtained images of the entire planet at high resolution and, crucially, at different angles to the sun that show features Mariner 10 could not in the 1970s," said Steven A. Hauck, II, a professor of planetary sciences at Case Western Reserve University and the paper's co-author.

Paul K. Byrne and Christian Klimczak at the Carnegie Institution of Washington have led a team that used MESSENGER's detailed images and topographic data to build a comprehensive map of tectonic features. Called scarps and ridges, the mapped features are similar to the tucks that a tailor makes to take in the waist of a pair of pants. Based on this new data, the team estimates the planet has contracted between 4.6 and 7 kilometers in radius.

Source: EurekAlert! [http://www.eurekalert.org/pub_releases/2014-03/cwru-mcm031414.php]

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[Doclector]

So...either they don't know why, or it's somewhere in this article without me being able to read the science stuff properly, but is there any particular known reason why it's shrinking? And so "fast"?

 

[Angelous Wang]

So...either they don't know why, or it's somewhere in this article without me being able to read the science stuff properly, but is there any particular known reason why it's shrinking? And so "fast"?

They did not state why in the article and they probably not will to say just to play it safe from bring wrong.

But the most likely "why" is the fact the sun is continuously expanding which means the planet is getting closer and closer, which can cause the planets core to heat up as the planet itself is exposed to more heat which could ether increase the gravity as the core speeds up (crushing itself) or melt/react materials that did not previously (decreasing empty space inside the planet). Or simply the gravity field of the ever enclosing sun is manipulating/interacting the planets own causing it to crush itself.

Their prediction of the planet age cycle only considered the planet itself and did not account for external sources.

 

[Pyrian]

It's just cooling. Perfectly ordinary sort of contraction.

 

[OneCatch]

So...either they don't know why, or it's somewhere in this article without me being able to read the science stuff properly, but is there any particular known reason why it's shrinking? And so "fast"?

They did not state why in the article and they probably not will to say just to play it safe from bring wrong.

But the most likely "why" is the fact the sun is continuously expanding which means the planet is getting closer and closer, which can cause the planets core to heat up as the planet itself is exposed to more heat which could ether increase the gravity as the core speeds up (crushing itself) or melt/react materials that did not previously (decreasing empty space inside the planet). Or simply the gravity field of the ever enclosing sun is manipulating/interacting the planets own causing it to crush itself.

Their prediction of the planet age cycle only considered the planet itself and did not account for external sources.

I don't think so...

The sun isn't continuously expanding throughout it's life - expansion occurs rapidly during the red giant phase, late in the star's lifecycle.
Rapid rotation does not beget an increase in overall gravity. If anything you'd see a small reduction in surface gravity along the equator and the planet becoming more oblate.

Gravitational torsion is also unlikely. You do see it on Io [http://en.wikipedia.org/wiki/Io_(moon)#Tidal_heating], but that's not purely a result of Jupiter's (prodigious) gravitational field, it's more to do with harmonics of other moons. And there's nothing in Mercury's 'neighbourhood' which would cause it.

It might be to do with internal material cooling down [http://www.newscientist.com/article/dn14255-mercury-the-incredible-shrinking-planet.html]. Most material inherently contracts as it cools, though perhaps more importantly the cooling might be something of a runaway cycle. If it cooled enough for the core rotation to begin to reduce gradually, then the frictional heat from said rotation would no longer be generated. And then you would see the total volume beneath the crust reducing to cause the buckling.

 

[BoogieManFL]

Cooling, And maybe it gets nailed by ejections from time to time? And/or just being closer to focal point of the solar winds? Probably a combination of various things in any event.

Regardless, that's a huge change.

 

[PrinceOfShapeir]

Okay, even on a geologic timescale four billion years is a long time. The universe is, what, 13.7 billion? Somewhere in that range. Seven kilometers lost in over a quarter of the life of the universe is not rapid by any stretch.

 

[Agente L]

I don't think "rapidly" is the correct word to use here.

Even when we are talking about interstellar bodies.

 

[Johnny Novgorod]

You might say Mercury is NOT rising.

 

[DracoSuave]

So...either they don't know why, or it's somewhere in this article without me being able to read the science stuff properly, but is there any particular known reason why it's shrinking? And so "fast"?

They did not state why in the article and they probably not will to say just to play it safe from bring wrong.

More likely, they haven't got a hypothesis for that yet, and scientists aren't really the sorts to announce cause before the data is in to infer cause. All they have right now is the effect.

The most likely cause is probably erosion from solar wind, but 'most likely' means what they test first, not what they announce.

 

[Strazdas]

Shrinking Rapidly by up to seven kilometers in radius over the past four billion years.

Such a misleading title that it makes others pale in comparison.

In aboslutely no measurement of time is 4 billion years rapid. especially 7 kilometers. 7 kilometers a year would be something we could perhaps call rapid considering our livecycle. but thats about as much as it goes.

 

[medv4380]

So...either they don't know why, or it's somewhere in this article without me being able to read the science stuff properly, but is there any particular known reason why it's shrinking? And so "fast"?

It's because it had a liquid core at one point in time. When that core cooled the planet shrunk. Most substances when they are cooled shrink in size. There are exceptions like water were it has a larger volume as a solid then it does as a liquid. Water is at it's most dense state at 4 degrees C.

How much it shrinks depends on how hot it started out at and what it's core is made out of.

Why it contracted more than our models predicted is easy. Our models have been horrible wrong for many years about how a solar system forms. All of the solar systems that we've discovered have planets that are impossible under our old models. That's mostly because all of our models were based off of our only observable solar system, our own, and only for a short period of it's existence, last 10k years of recorded history give or take.

The simple solution is the Mercury started off much hotter, or it's core is made of a material that contracts much more than we thought it would.

 

[KiKiweaky]

When you said rapidly in the title I thought it happened last night, forgot we were talking in cosmic terms here haha

 

[beastro]

I don't think "rapidly" is the correct word to use here.

Even when we are talking about interstellar bodies.

It's a typical space article: Sensational title to lure in most that would just ignore it.