Outsiders look in

Astronomers have unveiled a 180-foot-long poster showing the sharpest most detailed infrared view ever recorded of stars and dust in the inner Milky Way. To complete the portrait, researchers stitched together more than 800,000 infrared images taken by NASA’s Spitzer Space Telescope, covering a swath of sky 120 degrees across and one degree above and below the plane of our dusty, disk-shaped galaxy.

The Spitzer mosaic is expected to be the gold standard for studying the inner region of the galaxy for years to come, notes Barbara Whitney of the Space Science Institute in Madison, Wis. Because Earth resides inside the Milky Way’s dusty disk, the view of the inner galaxy is blocked in visible light, but it can be penetrated by infrared detectors.

The poster was presented in St. Louis at the meeting of the American Astronomical Society.

Spitzer peered 60,000 light-years into the murk, capturing detail all the way to the other side of the galaxy.

One Spitzer team analyzed shorter-wavelength infrared emissions, which are sensitive to warmer dust and organic molecules called polycyclic hydrocarbons (portrayed in green), typical of the dusty shells surrounding stellar embryos. The images also show hundreds of bubbles, or curved rides in the green-colored clouds. The bubbles, filled with graphite dust (red wisps), are generated by winds from young stars (yellow and red dots) as they blow away their dusty cocoons.

Another team examined images taken by Spitzer at longer infrared wavelengths, which record colder dust. Together, the images will enable astronomers to catalog some 100 million Milky Way stars.

Readers can zoom in and pan through the images at www.alienearth.org/glimpse.