Category Archives: Milky Way Galaxy

Milky Way Galaxy

Cosmic Exploration

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Starting in Our Own Galaxy

The Milky Way from Cerro Paranal, home to European Southern Observatory's Very Large Telescope. Courtesy ESO/H.H. Heyer.

It’s been a tumultuous November and I’m glad that December is finally here. I spent much of last month on travel, hence my light posting schedule. But, now I’m back and catching up on something I LOVE to do:  read about astronomy.

A sample of Wally Pacholka's amazing astrophotography. Click on the image to see a gallery of images accompanying Ken Croswell's article. Linked to by permission of National Geographic as part of a review.

Top of my pile was an amazing article in the December 2010 National Geographic by Ken Croswell called “Star Struck.” It’s illustrated by well-known astrophotographer Wally Pacholka and also includes views of our galaxy from the great observatories.

No matter how many times I look at astro-images, the cosmos still takes my breath away. And, that’s kind of what it does for Ken, too.  His article explores the Milky Way in lovely, poetic detail.  Not for Ken (or me) the pedantic descriptions of our home galaxy.  To my delight, he uses language that draws a great picture in your mind of this behemoth galaxy we call home:

“It’s hard to be modest when you live in the Milky Way.

Our galaxy is far larger, brighter, and more massive than most other galaxies. From end to end, the Milky Way’s starry disk, observable with the naked eye and through optical telescopes, spans 120,000 light-years. Encircling it is another disk, composed mostly of hydrogen gas, detectable by radio telescopes. And engulfing all that our telescopes can see is an enormous halo of dark matter that they can’t. While it emits no light, this dark matter far outweighs the Milky Way’s hundreds of billions of stars, giving the galaxy a total mass one to two trillion times that of the sun. Indeed, our galaxy is so huge that dozens of lesser galaxies scamper about it, like moons orbiting a giant planet.”

The article goes on to talk about the details of the Milky Way, derived from astronomy’s most recent explorations of it. Modern research is telling us a lot about the galaxy, and in particular, the action of its central, supermassive black hole in tossing stars out of our galaxy via its gravitational influence on binary pairs.  like You don’t have to be a scientist immersed in the detailed study of the Milky Way and its place in the hierarchy of cosmic structure  to appreciate knowledge like this.  It’s fascinating stuff. And, made even more so by writing like Ken’s and images like Wally’s.  Go check out the article and immerse yourself in the Milky Way!


black holes, Milky Way Galaxy

PSST!! Wanna See the Middle of the Milky Way?

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Look Over Here…

Image:Milky way 2 md.jpgIt may come as a surprise to folks to learn that we on Earth don’t live in the middle of the Milky Way Galaxy. We actually live out in the suburbs, about 26,000 light-years away from all the action at the center of our stellar city. That’s actually a good thing, because from all accounts, the core of the Milky Way has a black hole or two, and a whole lot of starburst activity and other stuff going on, some of it not very healthy to be around. Those aren’t conditions conducive to a nice quiet life on a water-bearing world such as ours.

Nonetheless, like urban folk all over the world, sometimes we get an itch to see the “downtown” area with its bright lights and excitement. So, we try to look at the center of the galaxy, only to find that it’s hidden by dust clouds. In northern hemisphere summer, you can go out a couple of hours or so after sunset and look south toward the constellation Sagittarius (shown in the image above from Wikipedia). Just off the tip of the spout in the teapot shape of Sagittarius is where the center of the Milky Way is located. The bright clouds are stars that lie between us and the core of the galaxy, which is hidden behind dust clouds. For folks in the southern hemisphere, Sagittarius is going to be overhead or even north of overhead (depending on where you are). But, no matter where you live, if you can get outside and take a gander at Sagittarius, you’ll be looking toward the heart of our home galaxy.

Now, it turns out we can look through that dust if we use a telescope equipped with infrared detectors. Infrared light CAN get through the dust. The image at left is from the Spitzer Space Telescope, and it shows the core of the galaxy-the stuff we can’t see with our visible-light eyes. There are hundreds of millions of stars packed into that scene, along with dark dust clouds that even infrared light couldn’t pierce.

It’s kind of fascinating to go out and look up at that region of the sky, which seems rather placid in visible light. Yet, behind all those dust clouds are some fascinating events taking place. Think about it when you go out to check out the center of our galaxy when you’re stargazing over the next couple of months.