Beneath its Sun-scorched exterior, the planet Mercury is cooling, which is causing it to shrink ever so slightly, scientists said Sunday. Over the last 3.8 billion years, the planet has shrunk by up to 14 kilometers (8.8 miles) to reach its present diameter of 4,800 km (3,032 miles), 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 percent of the planet suggested a contraction of 1.6 to six kilometres (one to four miles) 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.
GMT 09:14 2017 Wednesday ,18 October
Is facial recognition the stuff of sci-fi? Not in ChinaGMT 08:31 2017 Saturday ,23 September
Vision 2030 will take Saudi Arabia into the futureGMT 20:37 2017 Thursday ,07 September
NASA captures images of strong solar flaresGMT 20:39 2017 Wednesday ,30 August
United Technologies near deal to buy Rockwell Collins: reportGMT 13:41 2017 Saturday ,19 August
Eclipse-chasers trot the globe, addicted to Moon's shadowGMT 17:47 2017 Wednesday ,16 August
NASA: let's say something to Voyager 1 on 40th anniversary of launchGMT 16:41 2017 Friday ,11 August
Asteroid to shave past Earth on Oct 12: ESAGMT 21:32 2017 Tuesday ,18 July
Japanese engineers develop headset-less VR systemMaintained and developed by Arabs Today Group SAL.
All rights reserved to Arab Today Media Group 2021 ©
Maintained and developed by Arabs Today Group SAL.
All rights reserved to Arab Today Media Group 2021 ©
Send your comments
Your comment as a visitor