Astronomy Picture of the Day

Explanation: Although the Earth is round, our Galaxy appears truly flat. This was shown in dramatic fashion by the COsmic Background Explorer (COBE) satellite which produced this premier view of the central region of our own Milky Way Galaxy in infrared light in1990. The Milky Way is a typical spiral galaxy with a central bulge and extended disk of stars. However, gas and dust within the disk obscure visible wavelengths of light effectively preventing clear observations of the centre. Since infrared wavelengths are less affected by the obscuring material, the Diffuse InfraRed Background Experiment (DIRBE) on board COBE was able to detected infrared light from stars surrounding the Galactic centre and produce this image. Of course, the edge on perspective represents the view from the vicinity of our Sun, a star located in the disk about 30,000 light years out from the centre. The DIRBE module used equipment cooled by a tub of liquid helium to detect the infrared light which, composed of wavelengths longer than red light, is invisible to the human eye.