Sky at Night Magazine - - CONTENTS - David Chud­win

What does in­frared re­veal about the Uni­verse that op­ti­cal light does not?

We used to sum­marise in­frared as­tron­omy as ‘the old, the cold, and the dirty’. The old be­cause the cos­mic ex­pan­sion red­shifts light from dis­tant ob­jects into the in­frared; this is some of the old­est light in the Uni­verse. The cold be­cause in the in­frared we can see ob­jects which are too cool to ra­di­ate much vis­i­ble light. The dirty be­cause much of the in­frared light that we see is ra­di­ated by par­ti­cles of in­ter­stel­lar and cir­cum­stel­lar dust, and also be­cause dust clouds that are opaque at vis­i­ble wave­lengths may be quite trans­par­ent in the in­frared.

What do you think have been Spitzer’s high­lights?

First would be the iden­ti­fi­ca­tion of seven Earth-sized ex­o­plan­ets – at least sev­eral of which are po­ten­tially hab­it­able – or­bit­ing the same star some 40 lightyears from Earth. This is one ex­am­ple of our work on ex­o­plan­ets, which has cer­tainly been a high point of the mis­sion. An­other area of ma­jor im­pact has been our study of the ear­li­est, most dis­tant galax­ies. Work­ing in tan­dem with the Hub­ble Space Tele­scope, we have iden­ti­fied galax­ies that are seen as they were when the Uni­verse was no more than a few per cent of its cur­rent age and size. One-off re­sults, such as the spec­trum of the in­te­rior ma­te­rial of Comet Tem­pel I as re­vealed by the Deep Im­pact mis­sion, or the dis­cov­ery of C60 (in­ter­stel­lar buck­y­balls) in space have been very ex­cit­ing as well.

Michael Werner is a se­nior re­search sci­en­tist at the NASA Jet Propul­sion Lab­o­ra­tory, Cal­i­for­nia In­sti­tute of Tech­nol­ogy. He has been the lead sci­en­tist for the Spitzer Space Tele­scope since 1984.

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