Mercury Shrinkage May Be 30% Greater Than Previously Thought
New study attributes planet's contraction to cooling iron core, leading to surface tightening.
AI-assisted coverage comparison, editor-supervised · How this was made
This composite image provided by NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington on Oct. 22, 2013, shows Mercury as it appeared to the Messenger spacecraft following a flyby of the planet. (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington via AP)
Photograph: CTV News (embedded from source)
What this story says
- Mercury's diameter may have decreased by up to 14 miles (23 kilometers), a shrinkage potentially 30% larger than previously estimated.
- Researchers attribute the planet's contraction to its internal iron core cooling and shrinking, which tightens the surface.
- A new study published in Geophysical Research Letters used maps of Mercury's faults and surface roughness to reassess its shrinkage.
- The European and Japanese BepiColombo spacecraft is scheduled to enter orbit around Mercury in November.
Who covered it
Percentages are shares of the 32 outlets carrying a published leaning rating. 8 of the 40 outlets we know ran this story carry no rating and are not counted in them. Coverage measured .
Trust
42/100
Craft
57/100
Hype
41/100
40 sources · methodology
Scientists estimate that Mercury may be shrinking 30% more than previously believed, potentially losing up to 14 miles (23 kilometers) in diameter. This contraction is attributed to the planet's hot iron core cooling and contracting over billions of years, causing its surface to tighten.
The findings, published in the journal Geophysical Research Letters by researchers from the German Aerospace Center's Institute of Space Research, were derived by comparing maps of Mercury's faults and geologic signs of contraction with newer maps detailing surface roughness. The study suggests that rougher areas, possibly obscured by impact debris, may have hidden the full extent of the shrinkage.
Coverage comparison
The European and Japanese BepiColombo spacecraft, designed for a fuller survey of Mercury, is expected to enter orbit around the planet in November.
What the coverage left out
None of the left, centre, or right-rated reports below mention the specific names of the researchers from the German Aerospace Center's Institute of Space Research, other than Gaku Nishiyama, who is identified as the study's lead author in the full report from CTV News.
Still developing. We have re-checked which outlets are covering this 3 times, most recently on 10 Sept 2026, 19:45, and will add the sides that appear.
How each side covered it
Our own reading of the reporting listed below, written from the outlets’ articles rather than quoted from them. The reasoning is set out on our methodology page.
Left
15 rated outlets
- Reports from outlets rated left led on the finding that Mercury is shrinking more than previously thought. They highlighted the 30% greater shrinkage and the loss of up to 14 miles (23 kilometers) in diameter. Several reports mentioned the comparison of Mercury to a grape shriveling into a raisin.
Centre
14 rated outlets
- Centrist reports also focused on the increased rate of Mercury's shrinkage, noting the potential loss of up to 14 miles (23 kilometers) in diameter. The cause, the cooling and contracting iron core, was frequently mentioned. Some reports included details about the BepiColombo mission's upcoming arrival at Mercury.
Right
3 rated outlets
- Right-rated reports highlighted that Mercury may be shrinking faster than scientists expected, with some stating the shrinkage could be 30% greater than previously believed. The loss in diameter of up to 14 miles (23 kilometers) was also noted.
Questions about this coverage
- How did the left and right cover Mercury Shrinkage May Be 30% Greater Than Previously Thought?
- Of the 32 outlets on this story carrying a published leaning rating, 47% are rated left, 44% are rated centre, 9% are rated right. Those percentages are shares of the rated outlets, not of every outlet that ran it, which was 40. The sections above set out what each side emphasised, in its own terms.
- Is Mercury Shrinkage May Be 30% Greater Than Previously Thought left or right?
- Neither side dominates it. Of the 32 rated outlets on this story, 47% are rated left, 44% are rated centre, 9% are rated right, and no side holds the 70% this site would want before calling a field one-sided. A story is not left or right in any case; the outlets that carried it are what carry ratings.
- Is the coverage of Mercury Shrinkage May Be 30% Greater Than Previously Thought biased?
- Mercury Shrinkage May Be 30% Greater Than Previously Thought is one event reported by 40 outlets, and this page does not rate the story as biased or unbiased. What it publishes is the spread: which outlets ran it, where named rating organisations place each of them on the spectrum, and what each side chose to lead with. A leaning rating describes an outlet's record over time, not this article, and the two should not be run together.
- Which outlets covered Mercury Shrinkage May Be 30% Greater Than Previously Thought?
- 40 that we know of, every one of them listed further up this page with a link to its own report and to what we hold on the publisher. Nothing here is a summary of somebody else's summary: the outlets are named so the original reporting can be read.
- How much is Mercury shrinking?
- Scientists estimate Mercury's diameter may have shrunk by up to 14 miles (23 kilometers), a figure potentially 30% greater than previously believed. This contraction is attributed to its internal iron core cooling and shrinking.
- What is causing Mercury to shrink?
- The shrinkage is caused by Mercury's hot iron core cooling and contracting over billions of years. This internal process tightens the planet's surface, similar to how a grape shrivels into a raisin.
- When will the BepiColombo spacecraft reach Mercury?
- The European and Japanese BepiColombo spacecraft is expected to enter orbit around Mercury in November. It will conduct a fuller survey of the planet.
Read it at the source
40 outlets, grouped by the leaning a published rating gives them. Every headline links to the original; an underlined outlet name opens our profile of that publisher.
Left
15- Mercury Is Shrinking Faster Than Thought, New Analysis Of Its Many Wrinkles Reveals (opens IFLScience in a new tab)
IFLScience — is IFLScience biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens The Seattle Times in a new tab)
The Seattle Times — is The Seattle Times biased? Our profile of this outlet
- The planet Mercury may be shrinking faster than previously believed (opens The Toronto Star in a new tab)
The Toronto Star — is The Toronto Star biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens The Times-Tribune in a new tab)
The Times-Tribune — is The Times-Tribune biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens The Independent (US) in a new tab)
The Independent (US) — is The Independent (US) biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens The Independent in a new tab)
The Independent — is The Independent biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens The Daily Star in a new tab)
The Daily Star — is The Daily Star biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens Oskaloosa Herald in a new tab)
Oskaloosa Herald — is Oskaloosa Herald biased? Our profile of this outlet
Show 7 more
- Little Mercury may be shrinking faster than scientists expected (opens ABC News in a new tab)
- Scientists are trying to figure out if Mercury is even smaller than expected (opens CNN in a new tab)
- Scientists Drastically Underestimated How Much Mercury Has Shrunk (opens Gizmodo in a new tab)
- Little Mercury may be shrinking faster than scientists expected (opens NBC Dallas-Fort Worth in a new tab)
NBC Dallas-Fort Worth — is NBC Dallas-Fort Worth biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens The Hamilton Spectator in a new tab)
The Hamilton Spectator — is The Hamilton Spectator biased? Our profile of this outlet
- The planet Mercury is shrinking far faster than we thought (opens Scientific American in a new tab)
Scientific American — is Scientific American biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens Durango Herald in a new tab)
Durango Herald — is Durango Herald biased? Our profile of this outlet
Centre
14- Little Mercury may be shrinking faster than scientists expected (opens The Record in a new tab)
The Record — is The Record biased? Our profile of this outlet
- Mercury shrinking more than scientists previously thought (opens Purdue Exponent in a new tab)
Purdue Exponent — is Purdue Exponent biased? Our profile of this outlet
- Mercury is shrinking faster than we thought. What's going on inside of it? (opens Space in a new tab)
- Little Mercury may be shrinking faster than scientists expected – WTOP News (opens Washington Top News in a new tab)
Washington Top News — is Washington Top News biased? Our profile of this outlet
- This planet may be shrinking faster than scientists expected (opens CTV News in a new tab)
- Little Mercury may be shrinking faster than scientists expected (opens My Mother Lode in a new tab)
My Mother Lode — is My Mother Lode biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens WBAL in a new tab)
- Little Mercury may be shrinking faster than scientists expected (opens The Grand Junction Daily Sentinel in a new tab)
Show 6 more
- Little Mercury may be shrinking faster than scientists expected (opens The EagleHerald in a new tab)
The EagleHerald — is The EagleHerald biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens Henry Herald in a new tab)
Henry Herald — is Henry Herald biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens Bozeman Daily Chronicle in a new tab)
Bozeman Daily Chronicle — is Bozeman Daily Chronicle biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens WKMG in a new tab)
- Mercury may have shrunk much more than we thought, new study hints (opens Live Science in a new tab)
Live Science — is Live Science biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens Winnipeg Free Press in a new tab)
Winnipeg Free Press — is Winnipeg Free Press biased? Our profile of this outlet
Right
3- Little Mercury may be shrinking faster than scientists expected (opens The Daily Sentinel in a new tab)
The Daily Sentinel — is The Daily Sentinel biased? Our profile of this outlet
- Little Mercury may be shrinking faster than scientists expected (opens MY Northwest in a new tab)
MY Northwest — is MY Northwest biased? Our profile of this outlet
- Mercury Is Shrinking, and It Makes It a Lot Faster than It Was Thought. (opens ABC in a new tab)
Not rated
8- The Cliffs that Sweep Mercury Do Not Come From Any Meteorite Impact: the Planet Ratatines on Itself and Has Already Lost 23 Kilometers (opens SciencePost in a new tab)
SciencePost — is SciencePost biased? Our profile of this outlet
- The Mystery of Mercury: Why the Solar System's Smallest Planet Is Shrinking (opens Unknown in a new tab)
Unknown
- Science-Space: Mercury May Have Shrunk up to 30% More than We Thought (opens Unknown in a new tab)
Unknown
- Mercury shrinking more than scientists previously thought (opens Sunnyside Sun in a new tab)
Sunnyside Sun — is Sunnyside Sun biased? Our profile of this outlet
- Mercury Could Be Shrinking Faster than Scientists Expected. (opens Independent Español in a new tab)
Independent Español — is Independent Español biased? Our profile of this outlet
- The Mercury Planet Could Shrink Faster than Scientists Expected. (opens Mediafax in a new tab)
- The Planet Mercury Shrank to 23 Kilometers: What Is "Hidden" Inside It (opens reader.gr in a new tab)
- Mercury May Have Shrunk by up to 30% More than We Thought (opens ΑΘΗΝΑ 9,84 in a new tab)
ΑΘΗΝΑ 9,84 — is ΑΘΗΝΑ 9,84 biased? Our profile of this outlet
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