Astronomy Picture of the Day

Explanation: The Spitzer Space Telescope's encompasing infrared view of the plane of our Milky Way Galaxy is hard to appreciate in just one picture. In fact, more than 800,000 frames of data from Spitzer's cameras have now been pieced together in an enormous mosaic of the galactic plane - the most detailed infrared picture of our galaxy ever made. The small portion seen here spans nearly 8 degrees, roughly the apparent width of your fist held at arms length, across the galaxy's center. The full mosaic is 120 degrees wide. Highlighted in the false-color presentation are curving green filaments of light from complex molecules - polycyclic aromatic hydrocarbons (PAHs) - that on Earth are the common, sooty products of incomplete combustion. The PAHs are found in star forming regions, along with reddish emission from graphite dust particles. Blue specks throughout the picture are individual Milky Way stars.

The Privileged Planet
NARRATION GUILLERMO GONZALEZ AND JAY RICHARDS HAVE CONDUCTED RESEARCH ON ANOTHER FACET OF THE GALACTIC HABITABLE ZONE.

THEY NOW ARGUE THAT THE EARTH IS ALSO LOCATED IN THE BEST SETTING WITHIN OUR GALAXY FOR ASTRONOMICAL RESEARCH.

GUILLERMO GONZALEZ "As it turns out, our position in the universe is not only critical for life but it's also surprisingly important for making scientific discoveries."

We're located near the mid-plane of the galaxy, a fairly highly flattened galaxy, between spiral arms in the region with very low dust extinction. While we are in the plane in the galaxy, that does not obscure a large part of the sky so we can have very clear views.

NARRATION FOR MORE THAN A CENTURY, THIS NEARLY IDEAL PLATFORM OF OBSERVATION HAS ENABLED ASTRONOMERS TO STUDY THE STRUCTURE OF THE MILKY WAY.

LOOKING TOWARD THE CONSTELLATION SAGITTARIUS ON A CLEAR NIGHT, FOR EXAMPLE, WE SEE THAT THE STARS IN OUR GALAXY ARE NOT UNIFORMLY DISTRIBUTED ACROSS THE SKY.

INSTEAD, THEY APPEAR AS PART OF A CONCENTRATED BAND --A FLATTENED DISK OF STARS, DUST, AND GAS 100 THOUSAND LIGHT YEARS IN DIAMETER.

GUILLERMO GONZALEZ "The Milky Way band in the night sky is us looking edge on into the plane of the galaxy."

"If we were living in the center of the galaxy things would be much more spherically distributed, so it would be very hard to distinguish things inside the galaxy from things that are outside."

"It's also very dusty…much dustier toward the galactic center than it is in our region. And so, views of the distant universe would be much more difficult to obtain. They would be much more compromised."

NARRATION SIMILAR PROBLEMS WOULD EXIST FOR ASTRONOMERS WORKING ON A PLANET LOCATED WITHIN ANY OF THE GALAXY'S SPIRAL ARMS.

HERE, DENSER CONCENTRATIONS OF DUST CLOUDS AND GAS ILLUMINATED BY STARS WOULD MAKE IT DIFFICULT TO DETERMINE THE SHAPE OF THE MILKY WAY …OR TO DISTINGUISH THE STARS IN OUR GALAXY FROM THE REST OF THE UNIVERSE.

JAY RICHARDS "On the surface of the Earth, we're really in the optimum position for seeing both the nearby structure of the Milky Way galaxy, as well as seeing the distant cosmos, as a whole.

So, once again, we see that best location for habitability and for producing a habitable planet is also the best overall position in the universe for scientific discovery. In this case, at the galactic scale."

"The most incomprehensible thing about the universe is that it is comprehensible." Albert Einstein

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