APOD Robot wrote:
Composed with three different telescopes and about 90 hours of image data the widefield mosaic spans an impressive 24 degrees across the sky.
I am in awe at the amount of work that went into producing today's APOD. The picture is very impressive, too.
My objection - if that is an objection at all - is that the photographer teased so much hydrogen alpha light out of this celestial area that the familiar bright nebular objects in Cygnus almost drown in all the red Hα light. It can't be easy for a newbie to pick out the North America nebula (left of bright star Deneb at top) is this "sea of red".
There are a couple of things that I personally appreciate very much about today's APOD. By placing the dark rift of dust in the center of the image (well, top center), the photographer brings home the idea that all this redness belongs, more or less, to the same huge nebular complex. That is not quite true, of course, but much of the nebulosity is probably at more or less the same distance from us.
But not necessarily. I think it was David Malin who once said that northern Cygnus is where a spiral arm in the Milky Way "turns back on itself ", so that we see nebulosities at different distances from us in the Cygnus constellation. The southern counterpart to Cygnus, where the spiral arm "turns back on itself, would be Carina, another nebula-rich part of the sky.
One more thing that I love about today's APOD is that it really brings out the remarkable runaway O-type star 68 Cygni and its nebulosity, Sharpless 119. This great star and its "binary nebula" can be seen at upper left in today's APOD. In my opinon, 68 Cygni and Sharpless 119 are every bit as remarkable as AE Aurigae and the Flaming Star nebula, but 68 Cygni is almost completely ignored!
The picture of 68 Cygni and its nebulosity in the attachment is by Davide de Martin.
- 68 Cygni.png (156.91 KiB) Viewed 3630 times
Finally, I would like to show you a Cygnus skyscape where the Hα light is not pronounced:
The Milky Way in Cepheus and Cygnus.
Thin Air photography.
In the picture at left, the North America Nebula is prominent in the center of the picture, with the Gamma Cygni (Sadr) nebulosity to the lower left of it. The round pink nebula is IC 1396, and the orange star to the right of it is Mu Cephei. Note the prominence of the starlight. In today's APOD, the starlight is often swamped by the Hα light.
Ann