In my
Observing the Moon & planets thread, I've provided a series of Challenges. I thought I'd do something similar here with this thread, but more along the lines of a theme than a Challenge. This is mainly because of the wide variety of apertures that scopes come in so I don't want to create a set of challenges that immediately excludes small scopes. Instead, it will be a series of themes with (I'm hoping) two or three different objects that will be as both examples, but also offer a range of difficulty so to test your visual acuity and yes your scope/aperture - some level of challenge is a good thing!
Theme No. 1
Dark pillars
1, T
he Fish Mouth in M42: With Orion making its way back into our evening sky, the easiest Dark Pillar to see is an excellent way to start out!
The "Fish Mouth" is the name of this dark pillar. It is seen as a dark "finger" that points towards the Trapezium. The Fish Mouth is held together by a bunch of protostars that are hidden deep withing this column of gas and dust, and the collective gravitational pull of these protostars is resisting the erosive power of the enormous energy blast that comes from the Trapezium. The Fish Mouth is not a dumb black lump either. It is very much a 3D cylindrical shape, and if your scope and eyes are up to the task it is possible to see the variation in shading that the Fish Mouth has.
Another great thing about the Fish Mouth is it can be easily seen under urban skies!
1A,
The Trapezium. While we are looking at the Fish Mouth, lets look at the Trapezium - this pocket sized dynamo packs a real punch not just in terms of power output, but there are many more than just four stars that make up this small open cluster. Four stars are easily visible even in a 2" scope. 6 stars are visible in larger scopes from 4". Here's the real kicker - push your aperture to 14" and over, and you will be able pick out at least 10 component stars!
2,
Eta Carina's skeletal fingers: In the very first post I made in starting this thread, both the NASA Tour and my sketches, show the skeletal-like fingers that are a couple of dark pillars in this huge nebula. These dark pillars are visible in scopes larger than 4", and if you are under urban skies they are JUST visible without any filters in an 8" scope. Under dark skies, these are easier to identify.
3,
The Pillars of Creation of M16: Ok, this one is for BIG scopes! The dark pillars that form the Pillars of Creation, also known as the Eagle that gives the Eagle Nebula its name, is a real challenge to see. Aperture is one, but also good transparency is necessary. If transparency is not up to scratch, you will see the glowing mass that is this nebula, but the dark pillars will not be distinguishable. The night I first saw these I saw them through my 17.5" scope. Later on that same night I had a look at it through a 25" scope, and the pillars were totally invisible all because in the hour between my last view of them in my scope and looking through my friend's scope, the transparency of the sky went to pot!
I think this is a good start to this series of observation themes. If there is any theme or object you would like me to offer, please just ask!
