Trip Report: Powder Mill
Last fall, I took a great astronomy/camping trip to Colorado and I found some great skies. But I was not happy with the extra day of driving that far. The gas and motel costs plus the time made me want something closer to home. So I started looking at places within a one-day drive from Gurnee. I looked for great (i.e., dark) skies, available camping and lodging. As a secondary consideration, I thought about latitude - it affects the length of the non-frigid viewing season and the set of celestial objects that can be viewed. All other things being equal, a lower latitude is preferable.
I used the Clear Sky Clock to find candidate locations in nearby states. The CSC has a feature that lets you view all the clocks for a state, so it was easy to browse. The list of clocks for the state includes a color-coded representation of the location's sky darkness. On the color scale, black is the best and white is the worst (major urban area). These correspond to the Bortle scale range of 1 (best) to 9. Illinois, Indiana and Kentucky had no clocks that indicated low light pollution levels. Iowa had a couple of interesting places, but Missouri had the most promise with several good (blue) and one excellent location (black). That excellent location was Powder Mill, a campground in the Ozark National Scenic Riverway surrounded by a very large Bortle 1-2 darkness area. (By comparison, our club dark site is about Bortle 5. The area within the rectangle of Chicago, Milwaukee, Madison and Rockford has nothing better than Bortle 5.)
So, I decided to head down to the ONSR during a time when the moon wasn't objectionable. My goal was to spend a few nights on astronomy and use my daytime for exploring the area and enjoying nature. I left on May 1 and the 500-mile drive - mostly on I-55 -- was pretty uneventful, although the last 120 miles toured me through a lot of small Missouri towns. When I arrived at the campground, I was pleased to see that I had the entire campground (all 8 sites) to myself. I chose the site with the best sky and setup my camp. The forecast for the first night was pessimistic early - lots of haze, probably not clearing until the next day. So after getting a few poor peeks at Jupiter in the evening haze, I went to sleep about 10:30 and expected to start my sky fun the next night.
However, about 2am, I woke up and decided to check outside to see if there was any clearing. Getting out of the tent at 2am is always tricky and when I finally popped out and looked up, I felt like I heard a cymbal crash! The Milky Way was blazing across the sky from my (limited) northern horizon down to the (pretty good) southern horizon. There were too many stars to be able to figure out constellations (at least as I know them from Illinois) and Jupiter was glaring at me from the western horizon. As I turned to view the rest of the sky, I realized that the star dome was clear from edge to edge. Of course, I did the little "woohoo" astronomer dance and caught my breath. Then I dove back into the tent to rig myself for the cold (30 degree) weather.
That first night, I was out riding the NexStar and swapping eyepieces until about 4 when the thin, waning crescent moon "blinded" me as it rose over a nearby hill. That one session would have been fully satisfying for the trip, but I was rewarded with 4 more nights that were near perfect sunset to sunrise. A couple of nights I had to fight the record low temperatures (ask me about my Coleman catalytic heater!), I struggled with maintaining battery power (that's a GOOD thing!) due to heavy use and I became very sleep deprived (yea!). When the batteries failed, I used binoculars and just plain stared at the beautiful sky. It was fantastic.
By comparison, I would rate this location as equivalent to the views I had at the Denver Astronomy Society dark site about 60 miles east of Denver at 5,000 feet. Denver has the advantage of altitude while Powder Mill has the advantage of low light pollution. I didn't do any semi-scientific magnitude comparisons. But I can say that the sky at the Powder Mill site isn't quite as sharp as the 7,000 views from New Mexico or my even higher views from the San Isabel National Forest in Colorado. For me, the best indicator was the "puff" around Deneb that includes the North America Nebula. At the forest site, this puff was very bright, distinct and textured. At the DAS site and in Missouri, the puff was clearly visible, but it didn't have the same brightness and texture.
My daytime drives and nature explorations showed me why the pollution is low in this area. First, the majority of land is owned by government agencies: the National Park Service, the Department of Agriculture, the Missouri Departments of Natural Resources and Conservation and the Army Corps of Engineers. The combined population of the two large counties surrounding the OSNR is 16,000. The nearest town is 14 miles away. The primary local businesses are farming and tourism. The nearest Wal-Mart (a key indicator of civilization, car dealerships and lights) is over 40 miles away. And because of the dominating government ownership of land, this large, dark area is likely to remain this way for many years because the nearby towns have little impetus for growth.
So I feel really great about the skies in this area of Missouri, but there are a couple of things to keep in mind. First, the campgrounds in the area are sometimes heavily wooded so astronomy could be impossible at some sites. Other campgrounds had decent access to the sky but if the campgrounds were fully in use, there could be some ground light pollution and disruptions. The nearby local national forests support "rustic camping" - basically find a spot and camp - but of course, you face the loss of indoor plumbing, easy water supply, etc. So are the skies of southeast Missouri worth the drive? Definitely. But plan on a little effort to find that perfect location to setup your tripod. I can't wait to get back!