Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.


Mercury, the incredible shrinking planet

17 March 2014, 11:04

Paris - Beneath its Sun-scorched exterior, the planet Mercury is cooling, which is causing it to shrink ever so slightly, scientists said on Sunday.

Over the last 3.8 billion years, the planet has shrunk by up to 14km to reach its present diameter of 4 800km, they said.

Mercury, like Earth, is believed to have a superhot metallic core.

But unlike Earth, it has no tectonic plates which bump and jostle and slide in response to the stress that heat loss causes on the planet's crust.

Instead, Mercury has just a single, rigid top layer, which means the stress is transmitted directly to the planet's surface, causing it to "wrinkle" into gouges and ridges as the planet cools.

Planetary geologists led by Paul Byrne at the Carnegie Institution for Science in Washington used a tally of these features to get a yardstick for the planet's thermal contraction, the term for shrinkage through heat loss.

They studied nearly 6 000 landforms recorded by Nasa's Messenger spacecraft to look for these telltales.

Earlier estimates based on images of only 45% of the planet suggested a contraction of 1.6  to 6km over the course of its history.

The starting point for the measurement is the end of the "late heavy bombardment" of the Solar System - a period that ran from around 4.1 billion to 3.8 billion years ago, when our star system was a shooting gallery of comets and other icy bodies which smashed into the nascent planets.

The study appears in the journal Nature Geoscience.


Tags space

Read News24’s Comments Policy

Comment on this story
Comments have been closed for this article.

Read more from our Users

Submitted by
Wilson Ochieng
Apologise for attack on Auditor G...

Apologise for attack on Auditor General, President Uhuru Kenyatta is told by Kisumu Senator Anyang Nyong'o. Read more...

Submitted by
Wilson Ochieng
Quit if you can't fight corruptio...

An MP has told President Uhuru Kenyatta to quit office if he cannot fight corruption. Read more...

Submitted by
Wilson Ochieng
Investigate Uhuru, Ruto for corru...

Investigate President Uhuru Kenyatta and DP William Ruto's offices over corruption, CORD leader Raila Odinga has said. Read more...

Submitted by
Victor Tinto
Its a 1 horse race to State House...

Its a 1 horse race to State House, DP William Ruto has mocked the CORD Coalition. Read more...

Submitted by
Victor Tinto
Enjoy your time left in power, We...

CORD Co Principal Moses Wetangu'la has told the Jubilee Coalition to enjoy its last few months in power before it is voted out in the 2017 elections. Read more...

Submitted by
Victor Tinto
Stop hiding in State House and sa...

ODM MP's have called on President Uhuru Kenyatta to release drought aid and to stop sitting on public funds. Read more...