Tuesday, August 21, 2012

The Milky Way

Well, the family and I just returned from a wonderful week on North Carolina's Outer Banks--Nags Head, to be exact.

I'll do a couple more posts about it, but today's has to do with astronomy, as did one of my posts last week I called Things Ultrarunners Know: Astronomy.

For the first time in years we saw the Milky Way--the galaxy in which we sit, on our return trip at night from an excursion down the Banks to Ocracoke Island.  The night was darker than ever, due simply to the lack of light pollution that far from the mainland.

Here are a couple shots of the Milky Way, followed by some non-technical explanation of what it is we are seeing.

[image credit  Nick Ulivieri]

[image credit Dan Schroeder]

In a nutshell, the Milky Way is a faint, milky-colored band of stars that you can see stretching across the night sky.  It used to be easy to see from practically anywhere, but light pollution is negating that ability. From Nick Ulivieri's site:

To put it simply, a galaxy is a massive, gravitationally bound group of stars, dust, and gases, and other stellar remnants. The Milky Way happens to be our home galaxy. Our galactic neighborhood is about 2/3 out from the galactic center of the Milky Way within the Orion–Cygnus Arm; one of many arms that gives our galaxy its spiraled shape.  The Milky Way is impressively large, spanning some 100,000 light years across.

Technically, we can always see the Milky Way since we live in it, but when I refer to the Milky Way in terms of photographing it, I’m describing photographing the galactic plane; the white, milky band that streaks across the southern sky...the Milky Way itself is a disc-shaped spiral, and given our position in the galaxy, our view of the galactic plane is head on. Just as if you were looking at the edge of a frisbee. What you are actually seeing in this white, milky band, are all of the densely packed stars, gas, nebulae, and dust that form this disc we call the Milky Way.

From the Cornell University astronomy site:

Because we are inside the Milky Way, we don't get to take any pictures of it from an angle "above" the galaxy - for example, like this beautiful picture of M31, the Andromeda Galaxy. (However, we can make an educated guess as to what the Milky Way might look like from such an angle - for example, see this artist's illustration.)

Instead, we only get pictures in which we see the structure of the Milky Way edge-on, from inside of it.

Hopefully, that's enough of the science.  The point of the post is that there are marvelous things in the sky that used to be common knowledge for everybody, but now are in danger of being missed.

And that would be a shame.

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