View Full Version : A celebration of dark skies

2007-Sep-17, 07:29 PM
I gave a talk at the Tennessee Star Party near Lynchburg last weekend (HST founding project scientist Bob O’Dell is a hard act to follow) and stayed around for a night’s gazing. For reliability reasons, I took my wife’s car, meaning that the trusty little Nexstar 5 was a better fit than the 10-inch Dob. Even so, there was lots to see. The hilltop was about as dark as one hopes to find in this part of the country; most of what I write will be a paean to the glories of dark skies.

The Moon set through a gap in he surrounding trees; Janssen sat nicely on the terminator, recalling its onetime glory (of maybe 3.5 billion years back) before being smashed by all those later craters. The wrinkle ridge crossing Mare Crisium drew comment from people setting up their gear and lining up on the Moon

Jupiter in twilight showed that the seeing was good – even in my 5-inch, Ganymede showed up as distinctly larger than Io or Europa. As the sky darkeed, I took my first looks at nebula. The Omega or Swan showed some extra nebulosity beyond the swan’s tail that I’m not used to seeing. And the Eagle Nebula showed up quite distinct from the star cluster, also a treat.

I couldn’t resist some of the galaxies in Ursa Major, as low in the sky as it was even at dusk. M51 was bright and the companion obvious. Even better, M101 popped right out. Its low surface brightness had always made this visually the most elusive Messier object from my usual murky skies.

Now it was getting really dark. The Dumbbell Nebulae revealed the “ansae” or handles that fill the gaps in its outline. Even the pieces of the Cygnus Loop or Veil nebula – NGC 6960, 6992, 6995 – showed up in the little 5-inch. With a nebula filter, I could trace most of the loop across multiple eyepiece fields. And this is usually such a hard visual target… I wasn’t the only one pointed that way. There was a commotion several spots away, so I wandered over to ask what the hoopin’ and hollerin’ was all about. When I got a turn at the eyepiece of a 16” with nebula filer, I saw and joined right in. A big arc of the Veil, with delicate filaments and loops shining right across the eyepiece. Tried to freeze that in my memory.

I’ve occasionally thought that NGC 7331 through a modest telescope looks a lot like the Andromeda Galaxy through binoculars. Had a chance to try that side-by-side. Yep. But tonight through the 5-inch, Andromeda was huge and brilliant, with inner asymmetry corresponding to the dust lanes. On a whim, I even caught its two more distant dwarfish elliptical companions NGC 185 and 147.

Sagittarius still shows above the trees. How about those nebulae? The Trifid looks a bit like its pictures, with both emission and reflection pieces. The three dust lanes could even be traced. And the Lagoon spanned the whole eyepiece field, showing hints of fine details right to the limits of vision.

Star clusters have become visual favorites of mine – no matter what one knows about seeing galaxies, the impact of seeing that handful of diamonds on black velvet with any realization that these are suns impresses me at a more basic level with cosmic vastness. M22, 13, 92, 36, 37, 38… I may remember now that 37 is the richest of the triplet in Auriga.

Back to galaxies. NGC 253 practically spanned the field with a 15mm wide-angle eyepiece. NGC 891 just barely showed up – lose the disk and inner bulge light, lose the parts that are easiest to see… M74 was easier than M101, and this was working so well that I looked at NGC 1052 and NGC 936 just because I remembered that they were in the neighborhood.

Before packing up, I had a look at a very nice video astronomy setup one of the attendees had. 14-inch Celestron, StellaCam III video camera, large dual-screen monitor and rolling setup in the back of a van… Galaxies were outlined in real time just as on the Palomar Sky Survey, and he was just setting up to record video for the Helix Nebula. This inspired me to run back up the hill to use the Mk I eyeball – yep, there it was, and a nebula filter even closed the circle. (He made a very interesting point with teaching implications, based on questions from students - "why aren't all those other people doing this instead of squinting at things they can't see anyway?" Well, I see implications for the perceived transparency of computers as part of systems used by students, anyway)

No substitute for dark skies – and around here it’s easy to forget what they’ll show you. I certainly mentioned being available for future years!