Milky Way Poster
Our Milky Way is a dusty place. So dusty, in fact, that we cannot see the
center of the galaxy in visible light. But when NASA's Spitzer Space
Telescope set its infrared eyes on the galactic center, it captured this
spectacular view.
Taken with just one of Spitzer's cameras (at a wavelength of 8 microns),
the image highlights the region's exceptionally bright and dusty clouds,
lit up by young massive stars. Individual stars can also be seen as tiny
dots scattered throughout the dust. The top mosaic shows a portion of the
galactic center that stretches across a distance of 760 light-years.
Thanks to Spitzer's excellent resolution, the dusty features within the
galactic center are seen in unprecedented detail. Four examples are shown
in the magnified insets at the bottom. The farthest left box shows a pair
of star-forming regions resembling owl-like cosmic eyes. To the left of
the "eyes," dark lanes of dust can be seen. This object is probably
located in a spiral arm between Earth and the galactic center, in contrast
to the following examples, which are all located at the galactic center.
The next inset to the right includes the extremely luminous "Quintuplet"
stars, a set of five massive stars believed to have buried themselves in
cocoons of dust. Just below and to the right of the Quintuplet is the
"Pistol" nebula, a bubble of ejected material from the central, massive
Pistol star. The finger-like pillars to the left are part of a structure
known as "Sickle." They are similar in size and shape to those in the
famous picture of the Eagle Nebula taken by NASA's Hubble Space Telescope.
Pillars like these are sculpted out of dense dust clouds by radiation and
winds from hot stars. The pillars in the Sickle were likely to have been
formed by a cluster of hot stars located to their right but not readily
visible here.
The third inset highlights a system of long, stringy structures that are
seen for the first time near the base of a region known as the "Arched
Filaments." These long filaments are about 10 light-years long and less
than 1 light-year wide. The bright star-forming regions to the right are
some of the brightest in the infrared sky.
The final inset to the right shows the center of our galaxy, which is the
brightest spot in the entire mosaic. The brightness is a result of dust
being heated up by a compact cluster of hot stars. The bright spot also
marks the location of a supermassive black hole, around which a rotating
ring of gas and dust known as the circumnuclear disk can be seen.
This image was taken with Spitzer's infrared array camera, using its
8-micron detector. It shows emissions from heated molecules in dust clouds
called polycyclic aromatic hydrocarbons.
