Andromeda’s Fuzzy Patch

The other night I went out around midnight to see what the skies looked like. We’d had a pretty major thunderstorm, which dumped some rain and then fled the scene, leaving behind starry skies.  The Milky Way was stretched overhead, and that looked pretty cool. From our location we make out the dark dust lanes, and since the Moon had already set, I had a good dark sky.  After gazing up at the Milky Way for a while, and checking out some of the star clusters near Sagittarius, I decided to hunt my old friend — the Andromeda Galaxy.

Now, the naked-eye view of the galaxy is certainly not as good as the image here. It looks very much like a fuzzy patch in the sky between the constellations Cassiopeia and Andromeda. These nights, I can spot it around midnight, after the whole area of the sky has risen up out of the Front Range light pollution and has cleared the mountains behind our area. It’s not spectacular to the naked eye, but that’s not what draws me to look at Andromeda again and again. The lure is the distance across which I’m seeing. This spiral galaxy lies some 2.5 million light-years away. The light from its millions and millions of stars have traveled around two and a half million years to reach my eyes.

If you think about it, the light that left Andromeda leapt out away from those stars around the time that our hominid ancestors (called Australopithecus) were still around — although their time came to an end about 2 million years ago, paving the way for humans (the genus Homo — which includes us) to evolve.  That’s a heck of a long time to our human way of thinking, but compared to the 13.7-billion-year-old age of the cosmos, it’s not so long.

This distance and time illustrate pretty clearly that space travel is a lengthy procedure. IF we could move at the speed of light and launch ourselves out to Andromeda, it would take US 2.5 million years to get there.

I actually explored this whole light-speed, traveling-time, distance relationship in a planetarium show documentary called Light Years From Andromeda. It was one of the first astronomy scripts I ever wrote — and has been through a couple of iterations in the years since then. But, even though I’ve updated the show, the basic story remains the same:  space is big, space is dark, and when you’re a light beam traveling between galaxies, it’s finally good to find a place to park.  At my eyes!