New ultrasharp tele­scopes will help sci­en­tists un­der­stand:

Science Illustrated - - CONTENTS -

Other worlds may not have a cli­mate quite as nice as Earth. Not nice, as in, rain­ing glass or molten iron. Find out why (and how) this can be pos­si­ble.

In re­cent years, as­tronomers have dis­cov­ered hun­dreds of new plan­ets. As they are lo­cated bil­lions of km from Earth, sci­en­tists used to know noth­ing about them, but new pow­er­ful tele­scopes have spot­ted enig­matic worlds, where ruby clouds and glass storms might be as com­mon as a lit­tle light rain here on Earth.

The early morn­ing will be cloudy, pos­si­bly with show­ers of molten i ron. In the af­ter­noon, tem­per­a­tures will rise by 700 de­grees, and the night is go­ing to be windy with wind gusts of up to 10,000 km/h. This is what the weather fore­cast is like on some of the plan­ets that sci­en­tists have spot­ted out­side the So­lar Sys­tem in re­cent decades. Known as ex­o­plan­ets, they or­bit stars bil­lions of km from Earth, and for years, as­tronomers have been un­able to make out much more than their sizes, weights, and dis­tances to their stars.

But in re­cent years, a new gen­er­a­tion of so­phis­ti­cated tele­scopes have pro­vided as­tronomers with new in­sight into the re­mote ex­o­plan­ets, and armed with new meth­ods, they can now ac­cu­rately cal­cu­late what the for­eign worlds look like. And with glass storms, light­ab­sorb­ing at­mos­pheres, and ruby clouds, they are noth­ing like Earth.

Space weather fore­casts

As­tronomers have dis­cov­ered some 3,500 plan­ets that or­bit dis­tant stars, but bear­ing the im­mense cos­mic dis­tances in mind, ex­ist­ing tech­nolo­gies will not al­low us to land a space­craft on a re­mote planet in the next cou­ple of decades nor will a tele­scope be able to take di­rect pictures of the worlds. So, as­tronomers have found new ways to find out, whether the worlds are sim­i­lar to So­lar Sys­tem plan­ets con­cern­ing make­up, at­mo­spheric con­di­tions, etc. – and, more im­por­tantly, is there life on the ex­o­plan­ets?

When as­tronomers de­tect ex­o­plan­ets, it is usu­ally by means of the tran­sit method. A tele­scope ob­serves the star’s light over a pe­riod of time, and if the light is re­peat­edly re­duced, it is an in­di­ca­tion that a planet is or­bit­ing the star, block­ing out some of the light at reg­u­lar in­ter­vals, as it passes in front of the star.

As­tronomers use the same prin­ci­ple, also known as trans­mis­sion spec­troscopy, when they study ex­o­planet weather. When the ex­o­planet passes in front of its star, it is sub­stan­tially il­lu­mi­nated from the back. As mol­e­cules re­fract the light dif­fer­ently, sci­en­tists who take a look at how the light is af­fected by the planet’s at­mos­phere can see ex­actly which mol­e­cules – such as iron – it con­tains. The at­mo­spheric pres­sure is cal­cu­lated by ob­serv­ing its ex­tent. A dense at­mos­phere, in which the pres­sure is high, does not ex­tend as far from the sur­face as a thin at­mos­phere with a low pres­sure. Sci­en­tists cal­cu­late the tem­per­a­ture based on the host star’s tem­per­a­ture and the dis­tance from the star to the ex­o­planet.

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