Wrinkled Mercury's shrinking history

Mercury is 4,880km wide and is dominated by its giant iron core. [BBC]

My tries: (based on checking the Longman dictionary)

  1. Mercury is noticeable and famous because of its very big iron core.
  2. Mercury is controlled by its very big iron core and that is why you see wrinkles on it surface.

Additionally I would be grateful, if you would not deem it as off-topic, to write the definition of wrinkle and shrink in this context.

2 Answers 2


"Dominated by" means "has as the most noticeable feature".

So, most of the near-5000-kilometer diameter of the planet is its iron core.

Similarly, a very large building is said to "dominate" the skyline, or a vital issue like the economy might "dominate" an election.

"Wrinkled" here just means the surface of the planet has ravines or canyons that (from a great distance) suggest wrinkles on a face or a piece of fabric.

I don't know what "shrinking history" means. Perhaps Mercury is not as old as scientists once believed.

EDIT: Someone apparently claiming to be Paul McCartney points out that "noticeable" could be interpreted as "noticeable on visual inspection". You can barely see Mercury at all, and even if you were close enough to see the surface, you still couldn't see the core. The article means, "If you looked at a cross-sectional diagram of the planet, you would see that Mercury is mostly iron core, with a thin layer of something else on top."

  • 1
    Note that shrinking history is in the title, and subject to the vagaries of headlinese. In this case, it means literally that Mercury has a history of shrinking in size.
    – choster
    Mar 17, 2014 at 18:27
  • 1
    While the 'most notable feature' meaning is certainly possible, the fact that the core isn't actually visible would suggest that in this case, 'dominated by' means 'mostly made up of'. Given the context (a statement about width), I would assume it means that the core makes up most of the width of the planet. Mar 17, 2014 at 18:46
  • Perhaps "noticeable" was not the best choice of word, something like "most important feature" or "feature that has the most impact on its overall nature". Presumably the core is not directly visible to someone looking at Mercury through a telescope, etc. I assumed Malvolio met "noticeable" in the sense of "noticeable if we were looking at a description or diagram or some other presentation of important features".
    – Jay
    Mar 17, 2014 at 21:22

Dominate in this context ([Mercury] is dominated by its giant iron core) means that most of Mercury is its iron core. Its iron core is an obvious, so noticeable part of Mercury. It's widely known that Mercury's mean radius is 2439.7 ± 1.0km, and its core's radius is approximately 1800 km.

enter image description here

Internal structure of Mercury:
1. Crust: 100–300 km thick
2. Mantle: 600 km thick
3. Core: 1,800 km radius
Source: http://en.wikipedia.org/wiki/Mercury_%28planet%29

Here is another way we could paraphrase the sentence and the headline.

Mercury is 4,880km wide and is dominated by its giant iron core.
Mercury is 4,880km wide. Mercury is mostly made up of its big iron core.
(In another word, Most of Mercury is its big iron core.)

Wrinkled Mercury's shrinking history
The history of Mercury's shrinking. It's getting smaller. Its surface is wrinkled.

"Shrinking" means becoming smaller. "Wrinkled" is an adjective and can be used to refer to skin (or surface, in our case) that has a lot of small lines on it. Here is a nice way to explain why Mercury's shrinking results in its being wrinkled, as I found in Meet Mercury, the incredible shrinking, wrinkling planet - latimes.com:

... signs of deformation should show up on the planet’s surface -- like a plump, smooth-skinned grape that dries up, shrinks and turns into a wrinkly raisin.

  • I'd quibble that the core doesn't necessarily have to be "most" of the volume or mass of the planet. Something can "dominate" without being "most of" the total. It just has to have a very large impact. For example, if you said, "George dominated the meeting", that doesn't necessarily mean that George was over 50% of the people present (presumably impossible unless he was the only one there), but rather that he controlled what happened, or spent a disproportionate amount of time speaking, or otherwise was a much bigger part of the meeting than anyone else.
    – Jay
    Mar 17, 2014 at 21:27

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