Tiny par­ti­cles re­spon­si­ble for Earth’s wet sur­faces

Re­search : Dust motes ‘stick to­gether’

The Press and Journal (Aberdeen and Aberdeenshire) - - NEWS - BY KIERAN BEAT­TIE

Sci­en­tists from St An­drews Uni­ver­sity be­lieve they could have solved the long­stand­ing mys­tery of why our planet is so wet.

An in­ter­na­tional team of re­searchers, work­ing in part­ner­ship with the Scot­tish in­sti­tu­tion, have now dis­cov­ered that tiny grains of dust, no larger than the head of a pin, can ac­cu­mu­late sub­stan­tial vol­umes of water from sur­round­ing gases and ice.

They have rea­soned that these mi­nus­cule motes and their ac­cu­mu­lated water could col­lide, stick to­gether and form a planet like Earth with enough water to fill its oceans.

The uni­ver­sity re­searchers, along­side col­leagues from Ger­many and the Nether­lands, con­cluded that the process could take just one mil­lion years – which is enough time, ac­cord­ing to com­monly ac­cepted cos­mo­log­i­cal evo­lu­tion sce­nar­ios – for the for­ma­tion of stars and plan­ets.

They be­lieve the wa­ter­rich dust could clump to­gether to cre­ate the very first peb­bles, fol­lowed by kilo­me­tre-sized boul­ders and, even­tu­ally, en­tire plan­ets.

Their re­search was pub­lished re­cently in the sci­en­tific jour­nal Astron­omy and As­tro­physics.

The ques­tion of why liq­uid water is so rel­e­vant on our planet, es­pe­cially com­pared to other heav­enly bod­ies in our lo­cal so­lar sys­tem, has long in­spired sci­en­tists across the globe.

Other hy­pothe­ses which have been put for­ward to ex­plain the ori­gin of Earth’s oceans, seas and rivers in­clude trans­fer­ral of water from comets and as­ter­oids.

Peter Woitke, of the Cen­tre of Ex­o­planet Sci­ence at St An­drews Uni­ver­sity, said: “The mys­tery as to why Earth has so much water has pre­vi­ously baf­fled re­searchers.

“One the­ory sug­gested that the water was de­liv­ered by icy comets and as­ter­oids that hit the Earth.

“A sec­ond sce­nario sug­gests the Earth was born wet, with water al­ready present in­side ten-kilo­me­tre (6.2 mile) boul­ders from which the planet was built.

“How­ever, the amount of water that these large boul­ders can con­tain is dis­puted.”

THE­ORY: Sci­en­tists think mi­nus­cule motes could have col­lided and formed plan­ets

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