I had to laugh when I saw first this image: it shows Spitzer's view of the famous North America Nebula, renowned because of its resemblance to the continent... when seen in visible light
. But the glowing gas seen by our eyes is nearly invisible in the infrared, where dust rules supreme. So this Spitzer picture was something of a shock to me (the previous picture in the gallery is to the same scale and shows the shape more clearly, where the visible light view is combined with an IR picture ).
I also had to smile because this image was taken by my old friend Luisa Rebull
, who studies young stars. Clouds like the North America Nebula churn out stars, but in visible light they're mostly hidden by dust. Only about 200 baby stars were known before Spitzer took a look, but Luisa has found more than 2000!
You can see some of them yourself in the picture; look to the left and just below center. There are dark features there studded with very red dots: those dots are young stars! The dust littering the cloud absorbs the visible light from the stars, but lets through the far-infrared, color coded as red in this picture. In visible light, this is the "Gulf of Mexico" region which defines the continental resemblance of this nebula.
You can also see the wispy pillowy structures surrounding the cloud, where winds of subatomic particles and the flood of ultraviolet light from the young stars eats away at the material there. In visible light the dust makes the iconic shape that our brains perceive as that of a continent, but it's in the infrared where the underlying science really shines.Original press releaseImage credit: NASA/JPL-Caltech/L. Rebull (SSC/Caltech)