Well, it’s official! With apologies to Al Jolson, just a quick blog post to note that I’ll be moving from Manhattan to Denver at the end of this month. Yes, it will still be plenty light-polluted in Denver, but obviously nowhere near the same level as it is here in the light-pollution capital of the universe, Manhattan. I’ll be more than happy to get almost another magnitude or so visually even from deep in the city where I’ll be. And I’ll eventually have the opportunity to get an eight-inch scope of some kind (the type remains to be seen) in my new apartment there, so I’ll be able to go even deeper and see all those dimmer Messiers that have eluded me all these years from my currently heavily light-polluted observing location.
One of the nice things about the move is that I will hopefully be getting a car so that I’ll be able to get out of the city and get to even darker skies. As you know, New York has an absolutely gigantic light dome, of course. But it also has vast, sprawling suburbs that require you to travel far, far out of the city to get to semi-dark skies. First, just look at the difference between the US starting about 200 miles west of the Mississippi and then east of that line:
Incredible, isn’t it? It’s like the population just drops right off a cliff there. The west is truly sparsely populated.
Take a look at the zoomable dark sky map here and zoom into the New York area. Yes, the entire city is whiter than white in terms of the light pollution. The nearest “blue” skies (meaning, really, really dark) are about 130 miles away to the northwest. Worse, that is at least a 2 1/2 hour drive, because it takes a while just to get away from the heavy traffic in the city. Five hours driving in one night? That’s a helluva lotta driving. No, thanks.
One of the really great things about Denver is that there is less of this sprawl. The result is that those truly dark skies are much, much closer to the city, and are easier to get to. Zoom in on Colorado generally, and you’ll see significant light pollution in a line, up and down what is called the Front Range. That’s the most populated corridor of Colorado that runs in a straight line from Fort Collins in the north down to Pueblo in the south along Interstate 25, and is just to the east of the Rocky Mountains. But just about 60-70 miles further east are first blue skies, and then another 10-20 miles after that, black skies. It would seem that I would be able to take Interstate 70 about 70 miles east of town in about an hour and ten minutes and get to some truly, incredibly dark skies. If I get a car, that is.
But what I’m really looking forward to is the huge increase in magnitude grasp these incredibly dark skies will give me. My limiting magnitude here in Manhattan is about 9.5 or so with my 5-inch Mak. It is theoretically capable of letting me go about 3 magnitudes deeper. In eastern Colorado, I’ll be able to test that limit out and see if I can get there. That’ll allow me to start seeing some structure in globulars and galaxies, and previously invisible nebula will leap out. An eight-inch scope will let me go another full magnitude deeper than that, all the way down to about 13.5. I’ve even been thinking about maybe getting a twelve-inch dob someday; if I can overcome my collimation phobia, that would take me all the way down to 14th magnitude.
Another nice benefit is that I’ll also be one degree further south in Denver than in New York. Hey, every little degree helps to get those far southern objects up out of the low murk of the atmosphere and be that much higher into the sky. Okay, who am I kidding; one degree won’t really make much of a difference. On the other hand, I will be able to quite easily drive just a couple/three hours south, say for a long weekend, right down I-25, to access darker, more southerly skies, and gain three more degrees of southern elevation over New York. Nothing to write home – or a blog post – about, but now we’re talking.
I’ll also be at altitude in Colorado; they don’t call Denver the Mile High City for nothing, although the meaning of that appellation may be shifting as of late. The altitude will help with both the seeing, because there’ll be that much less atmosphere to look through, and the darkness, lowering my limiting magnitude that much further. Unfortunately, being just downwind of the various peaks of the Rockies will counteract this increase in seeing. My understanding is that even with the altitude, the lunar and planetary detail suffers because of this.
An entirely new universe, just two weeks away!
(Well, a little longer than that, because I won’t have a car. Yet. But soon enough.)