Moon

Moon

Friday, 15 February 2019

Understanding Nebulae - Part 3


Getting the MOST out of your HUMAN eyes

Ok, we now know that our eyes are not the best at low levels of light. But, did you know that our eyes also have different areas that are more and less sensitive in low levels of light? That the less sensitive area to light holds both the greatest number of colour receptors and is also where we see things with the greatest detail - central vision. That the area that is most sensitive at low levels of light is also the area where less detail is seen - peripheral vision. AND that there is a sweet-spot between these two areas of our vision where we get both detail and light sensitivity!

This sweet-spot around our central vision is the area that we as observers need to use to maximize our capability at the eyepiece.

Here's an everyday example to demonstrate what I'm talking about. You are in your bedroom at night with all the lights off. Only a feeble light is visible illuminating the room. Have you noticed that when you look around the room in the dark, when you look directly at something that it somehow "disappears", but as soon as you look away to one side of that thing it somehow "reappears"!? The good news is two-fold - 1, you are not going mad - it's how our eyes actually do work; 2, it is this very feature of our eyes that we use at the eyepiece!

Looking at things this way, just to the side and not directly, is called AVERTED VISION. It is using that sweet-spot area around our central vision where there is a rich mix of both rods and cones as the central vision transitions to our peripheral vision. It is this area where there is that all important low light area of our vision where we get both detail AND low light sensitivity.

THIS is the one trick to maximizing our experience at the eyepiece!

Do not look directly at the object, but just to one side of it!

The good thing about using AVERTED VISION is it takes only an instant to learn, and only moments to master! You've been using averted vision all your life in dark rooms/environments, and you've never been aware of it! http://www.iceinspace.com.au/vbiis/images/smilies/happy04.gif

Below is a little example of how to utilize averted vision. The object in question is a globular cluster. Our immediate response is to look at it directly. That is fine with this sketch. But through the eyepiece, so see a globular cluster in all its splendour with its many thousands of stars all so clearly visible and individual, you DON'T LOOK AT IT DIRECTLY, but just to one side as indicated by the X. It can be to the left or right of the object, it doesn't matter. It just needs to be just off to one side.


Tip in locating objects

You may have also noticed another VERY ANNOYING thing when using your scope. When you are trying to find a faint object you are panning the scope from side to side, and you catch a glimpse of something faint and fuzzy out of the corner of your eye, but when you pan the scope back to that faint thing YOU CAN'T FIND THE BLASTED THING!!!  😡 This is because you are now using your central vision to spot that faint thing, when it was your peripheral vision - your most light sensitive vision - that spotted that thing.

The solution is an easy one, but a bugger of one to learn - DON'T LOOK FOR THE OBJECT while you pan the scope back!

This is a really easy thing, but a bugger of a trick to remember, and it still catches me out after 35 years of using telescopes! 😄 It is also totally counter intuitive to how we use our eyes every day. But it all has to do with the way our eyes work that I described above. If it was your peripheral vision that spotted that faint thing, then it must be your peripheral vision that needs to be used to reacquire it!



~x.X.x~


I hope these three article specific posts have been helpful to you as you start on your astro experiences. Many people become frustrated with astronomy because they don't understand how our eyes work, how to exploit their strengths, and the unfortunate expectations that the pretty pictures create in our minds. But astro can be a very satisfying experience. Just that as with all things we do, such as walking, driving, playing a sport, it takes time and understanding to make the most of these. Astro is also a quite pursuit, not a "smash'n'grab" one. Like a said earlier, rush things and you will miss things. Slow down, calm your heart, and the Universe will reveal itself to you!  😊

Alex.

Friday, 8 February 2019

Understanding Nebulae - Part 2


Why can’t I see colour through my telescope?

We have all seen those marvellous and colourful photographs from the Hubble Space Telescope.  Yet when we look through our telescopes, NONE of those brilliant colours are visible!

What the heck is going on???

There are two categories of reasons why:

The primary reason is human eye physiology. Our eyes while exceptional at seeing detail and colour under brilliant light, in the dim light that we do our astro, our human eyes are very poor. The resulting image is a "default" one of black and white. In dim illumination, our colour sensitive cones are not fired up enough to trigger a response. The rods in our eyes are able to be fired, but the image they produce is essentially a black and white one.

However, colour can be seen in some deep sky objects, and namely nebulae, but the variety of colours and their brilliance has a lot of "depends" reasons. And these reasons are why some people can see colours in these DSOs, yet other people see no colours what so ever.

The secondary reason for colour perception:

* Gender: 1/3 of all males have some degree of colour blindness, from oh-so-slight through to no colour perception at all (very rare). Yet colour blindness is rare in females.

* Age: Colour perception at low levels of illumination can change with age. I can atest to this! When I got my 17.5" scope about 8 years ago, the very first object I looked at was M42, the Orion nebula, I was able to see pinks, blues and greens in it! Yet today, same scope, and even better eyepieces, yet I have lost those lovely pinks, and the blues and greens are much less vibrant. Yet there are some lucky individuals whose colour perception doesn't change. <sigh>

* Health: Whole of body health can affect eye health and vision. Diabetes, smoking, excessive alcohol consumption, drugs (perscribed or illicit), and a myriad of other health complications can all work against not only colour perception, but also visual acuity.

* Genetics: One card we have no control over, and have mum and dad to thank for. There are some genetically inherited traits that mean some individuals have exceptional low light colour pereption, yet others struggle to see much at all little lone colour.

And of course, the whole lot of the above varies between individuals!

But all is not lost!

So, if at first you don't see colour, be patient. Looking through a telescope is a very different experience that our "daylight" accustomed eyes are used to. It takes a little time to re-train your eyes to see under these unique conditions. One part of this re-training process is to use "averted vision" in order to maximize detail perception. I'll elaborate a little more on averted vision in a following post here.

DON'T RUSH! Take your time, and be calm at the eyepiece, and you will allow your eyes to adapt. Rush, and you are only cheating yourself.

Do these things, and if you are one of the fortunate individuals with good low light colour perception, and you will be rewarded. There are not very many objects that do show us colour through the telescope, so if you cannot see colour, don't be disappointed. Heck, I've lost my ability to see those vivid colours in M42... 😭

Thursday, 7 February 2019

ARTICLE: Understanding Nebulae - what it is you are looking at


Hi all, the following is the first of a series of articles designed to help explain some of the things we see through the eyepiece, why we see some things and not others, some of the commons misconceptions regarding telescopes, and how to make the most of the telescope you have AND how to best exploit our very human eyes.  Of PRIME consideration for me though is to keep the tech-talk to a minimum so not to confuse, nor full of astro-jargon.  The articles will develop over a few parts.

The first article is about nebulae, why we see them the way we do on the most part without colour, what is actually going on inside them that gives them their shape, and tips on how to maximize your efficiency at the eyepiece.  

~x.X.x~

Understanding Nebulae - what it is you are looking at.

Part I
Nebulae can be beautiful stellar nurseries or the remnant ashes of a dying or dead star. In photographs they can also exhibit various colours, but mostly blue and red. And they can also exhibit a multitude of shapes and shades, from brilliant and colourful to dark and foreboding. Despite their many differences, what they all share is the forces of physics at play that form and mould them.

But what does it all mean?

One easy thing about understanding what you are looking at is you don’t need to have a degree in astrophysics, nor be a mathematics whizz. The concepts at play here are actually surprisingly easy to follow, and once you have the basic concepts figured out, then no matter what nebula you look at, you will be able to figure out what is going on with that nebula.

However, here I will let NASA do the heavy lifting for me in explaining nebulae! There is one NASA site that discusses the Eta Carina nebula using the images gathered of it by the Hubble Space Telescope. This Tour of Eta Carina will show you the structures and anatomy of a nebula, and by the end of the tour you will be able to recognise the various components and the forces at play. The greatest part of this is you will be able to use this knowledge with any other nebula you then look at.

What is especially good about this Tour is that the items being shown are ALL visible through amateur telescopes, depending on how large the telescope is, the bigger the aperture, the more details you will see. Yet even a modest 50mm telescope will reveal a lot that is mentioned in this NASA tour of the Eta Carina Nebula:

http://hubblesite.org/video/880/imag...ission-nebulae

BUT FIRST! Look at these sketches to prime you for your tour.

To help you along with your learning experience, below are two sketches I have done of the Eta Carina Nebula. Both were done from my home in Sydney. The first using an 8” scope, and the second a 17.5” scope. Please look at these pictures before you visit the NASA site. Then, AFTER completing the Tour, look at the sketches of mine again with your newly gained knowledge, and all of a sudden you will see so much more detail in the sketches that previously you had no idea what you were looking at! Two cosmic bubbles that have two different sources, dark pillars that resist erosion and hide protostars, brand new stars that have just kicked off their nuclear fires, glowing gas that is charged by the intense radiation of enormous stars, a myriad of details that are always on show, but hide from view only because of not understanding what you are looking at.

 



Now, having armed yourself with a new understanding of what nebulae show in their appearance, you will now be able to identify these same characteristics in other nebulae. At little further education to some other nebula types, such as Super Nova Remnants (the glowing crap left over after a supergiant star explodes) and Planetary Nebulae (the glowing shell of material blown off by smaller stars that are dying (the way our own Sun will end)), yet they all show elements and features seen in the Eta Carina Nebula.


I have deliberately chosen to illustrate this whole document with my sketches in order to demonstrate that the features shown in that tour of Eta Carina are not invisible through a telescope, and very much within visual reach. And by all means, look up photographs of the items below and see for yourself that the view through a telescope can reveal a hell of a lot!

M16, the Eagle Nebula:



M42, the Orion Nebula:



The Veil nebula:


Thor's Helmet:



The Helix Nebula:



Alex.

Monday, 6 August 2018

Sunset at the Straight Wall reveals amazing detail


Hi all,

This is my second lunar sketch done using eyeglasses.  I’ve adapted a headband magnifier so it can carry a pair of spectacles suited to my eyes.  I’m getting used to the new way of sketching as there is now an additional step in my eyepiece-to-sketch-pad routine.  But the difference using these specs makes is well worth any initial discomfort.

I got up very early on Sunday morning for the chance to sketch something during the ¾ phase of the Moon.  As it turned out, seeing wasn’t the best despite the wee hour and cool temperature, but the occasional glimpses of remarkable clarity made the effort worthwhile all the same.

With all the lunar features on view tonight, it was an old favourite that most caught my attention, Rupes Recta, the Straight Wall.  I’ve sketch the Straight Wall during the ¼ phase as the Sun rose over this escarpment (see below), but this particular phase had the Sun setting, and the wall instead of being a dark shadow, was brilliant white, and the very low angle the sun was at cast the most remarkable long shadows and revealed a textured surface and details of this area of Mare Nubium that were jaw-dropping remarkable.



From the above sketch of the Straight Wall, the higher angle of the Sun leads one to think that the flooded ghost crater the Wall sits in is relatively smooth and not particularly textured.

Now, move the phase forward some 14 days, with the Sun casting its last rays across this same area at a glancing angle, and a staggering textured and tortured surface is revealed.  The Straight Wall and Rima Birt are not the only geological formations here.  Just west and running parallel to the Straight Wall is a long straight “depression” or fold that is roughly as long at the Straight Wall itself.  This long depression is crossed by Rima Birt, and continues on straight northward.

Rima Birt itself is remarkable in that its official selenologic origins are somewhat uncertain.  Most likely it is a rift fault that then allowed lava to erupt up along through the fault.  And as my sketch progressed, I picked up two volcanic domes (Birt 1 & 2) at the northern end of Rima Birt, the larger of the two sitting right on top of the rile!

The glancing angle of the fast setting sun also reveals so many other obscure features.  The oh-so-faint rims of several ghost craters are just barely visible – one being outlined by the chain of mountains, west of the Straight Wall, that circumvents and suggest the basin in which the Straight Wall sits in.  A highly pock-marked field of craterlets lies scattered south of Birt.  The faded ray system that extends southward belonging to Birt.  Several winding folds of old lava flows form wrinkles across the moonscape.  Long string-like streaks of light are cast eastward from the northern end of the Straight Wall across a jet black otherwise invisible plain.  And of course the curious twin peaks of dark shadows cast by the crater Birt across the brilliant white escarpment.




Object:  Sunset along the Straight Wall and surrounds.
Scope:  8” SCT
Gear:  10mm Pentax XW, 200X
Date:  5th August, 2018
Location:  Sydney, Australia
Media:   White and grey soft pastels, charcoal and white gel ink on A5 black paper

This was a remarkable session for me.   From starting not wanting to repeat a feature I had sketched before, a little time spent with it showed an astounding amount of invisible details revealed only by having the sun at as low an angle as possible before it dips below the horizon.   Quite superb!

Alex.

Using Eyeglasses with Telescopes - one solution


Well, age has caught up with me.  I started to wear eyeglasses over the last couple of years as I’ve started to struggle with close up focusing.  This was fine with reading, but now I’m needing to use glasses with my sketching.  This has created a problem when I go to and fro between sketch pad and eyepiece and now needing to lift and replace the glasses from my nose.  This is a problem not just for those who sketch, but also for those people who make observing notes, and for microscope users too.

Lifting, holding and replacing traditional eyeglasses constantly is a fool’s game.  There had to be an easier way to make the switch.

I started looking into headband magnifiers.  Many of these come with an assortment of different lenses that provide different degrees of magnification.  I purchased a set that appeared to be light weight and as an added bonus has a pair of white LED lights built in.





My initial testing at home was most promising.  This headband set has a double articulating joint which allows or the lens to be lifted and for the whole LED assembly to be lifted too, and as the lens is attached to this element, the lens is able to clear the eyepiece safely.




The ultimate proof is using the headset at the scope while doing a sketch.  I used the headset on two occasions with the supplied lenses, once with a lunar sketch and the other with a DSO session.  As it turns out, the concept is good, but the supplied lenses are not.  The lenses are designed for close up work, and these lenses are not suitable for my purposes that has the sketch pad at a longer distance than these lenses work at.

Another problem with these lenses comes from the way they are made.  As the individual lenses are attached to each other with no spacing, the field of view when using these lenses is very narrow, and ultimately impractical.

My eyeglass script is mild, and at a pinch the ready-made glasses available at pharmacies  work well for me.  So, the thought occurred to me to swap the lenses that came with the headband for one of these inexpensive pharmacy eyeglasses.  If the experiment works, I can look at making a new set of lenses of my script.  By making use of these eyeglasses, I would also make the field of view much, much larger

So, I chopped up one of the supplied acrylic lenses to use the coupling mechanism it has, and attached it to the eyeglasses also using acrylic.  The arms on the eye glasses I cut off.  If I unscrewed the arms to remove the, it would have left two long tags would become a hindrance and get in the way when moving to and from the eyepiece.




Now for the third field test and proof of concept.  This was a lunar sketch.

The result was successful.  The new lenses are much easier to use, with no noticeable eye strain, and with a much larger field of view.  With this successful test, I can look at having a new eyeglass script made up for me that I can modify to fit this headband.  Of course, not having to use eyeglasses is easier, and I will need to get used to the actions of lifting and lowering the lens, but the gain of clarity of image is well worth whatever hassles using glasses presents.  I’ll post this latest lunar sketch in a separate blog entry.

Alex.

Monday, 30 July 2018

Total lunar eclipse above Sydney, July 2018


Hi all,

This particular lunar eclipse presented a unique opportunity – to see the eclipsed Moon set behind the Sydney skyline.

It required some investigating to work out the best vantage points.  The angle of the line of sight window was a small one, and the landscape of Sydney’s east is also very hilly, AND the harbour also presents its own points and islands that can present obstacles.  What I wanted was a vantage point that allowed for a good view from the Harbour Bridge in the north and the city’s CBD to the South,

I could have the Moon set behind the gorgeous harbour bridge, but vantage points for this were limited and would mean being too close to the city for the sort of image I was after.

The area between the Bridge and the CBD is rather empty so I preferred not to have the Moon set here.

A vantage point was needed that would have the Moon set behind the CBD, and with any luck, it will set very close to Sydney’s tallest building, Centerpoint Tower.

So, at 4am I found myself on the foreshore of Sydney Harbour in the grounds of Strickland House.  Stickland House is a beautiful manor built more than 150 years ago, and has a gunbarrel view of the City down the harbour.   From here I had an uninterrupted view of the City skyline.  There was a risk that predicted cloud cover could ruin the event, but this only made things more interesting with an element of risk.

The photographic camera I have is not designed for long exposure work, so my intention was not to capture a textbook pretty photo of the blood red Moon.  But I brought it with me for the odd chance that I could manage a photo of the eclipsed Moon, but more for photographing the spectacular skyline at sunrise.   My main tools for the event was a modest Brinno time lapse camera, a sketch pad, oil pastels and binoculars.  I’d be happy with a nice little time lapse video, and a sketch of the event which would be a very different way to present the lunar eclipse.

As the eclipse progressed, I still hadn’t worked out what to do sketch wise.  Then it hit me – I have a gorgeous skyline in front of me, and why not a sketched time lapse too!?  I had done a sketched time lapse of Comet Lovejoy a few years back, so not a new concept to me.  What made it even more appealing to me was the changing appearance of the red illumination of the Moon as it progressed through Earth’s shadow.  The threatening cloud sitting behind the skyline would also add to the complexity of the sketch and add to the movement of the final piece.

I was not alone at the foreshore vantage point I set up on.  When I arrived a met three mates there who are photographers.  I set up next to Dan Chee from Delta Charlie Images ( https://www.facebook.com/DeltaCharlieImages/ ).  Dan’s welcoming nature made the cold so much more bearable, and with his mates for a very jolly one too!  Dan posted his spectacular images of the eclipse on his Facebook page.

The time lapse sketch also shows Mars which was just a little to the left and above the Moon.  This is why there are only three apparitions of Mars despite there being four of the Moon.  The two streaky lines are of a couple of planes that crossed through the field.


Oil pastel on black paper

As I had to wait for some time between each new position of the Moon in my time lapse sketch, I passed some of this time by doing a quick oil pastel sketch of the blood red Moon as viewed through my binoculars.  What made the apparition  so interesting was the difference of the density of the red across the Moon as it transited through Earth’s shadow.  It gave a wonderful range of hues across the lunar surface, and this suited very nicely the brisk sketching form in using oil pastels.  Oil pastels are not a medium for very detailed work.  They are an excellent medium for a fast Impressionist style of sketching.


Oil pastel on black paper


I’m also pretty happy with the modest little time lapse video of the eclipsed Moon.  Mars is also very easy to see.  The Moon makes its last apparition around the 57 second mark at it comes in very close to Centrepoint Tower.  And of course I forgot the camera was rolling towards the end of the filming.  Well, it was very cold by the end and I wasn’t thinking too straight! LOL



I hope you have enjoyed my little collection of images of this lunar eclipse.  To finish off, I’ve included a couple of photos I took of the skyline of my home city as the Sun began to rise.









Alex.

Friday, 8 June 2018

Unique Planetary Alignment coming up in October this year!

Hi folks,

I've happened to have stumbled upon a very unique planetary alignment that will occur for a few days either side of October 18 this year!  All 8 planets, plus the Moon and Pluto will all be visible all at the same time.  This is one of the rarest planetary alignments visible!

Over the last few months I've started doing some sidewalk astronomy sessions, taking a telescope or two down to a popular spot along Coogee Beach near my home, and show people who are passing by a look at the Moon and any planets that happen to be visible on the night.  These sessions have been very popular with some people even calling their families and friends out from their warm homes to rush down to have a look at the Moon, Jupiter and Saturn! 😊

So, early this week I was doing some research for some future dates using an astronomy app that would be favourable in showing the Moon and planets when I notices something very interesting in October.  On the western horizon Mercury, Venus and Jupiter were all close together  soon after sunset.  It then occurred to me that Uranus might be up at that time as I was aware of its location in the sky.  Well, wouldn't you know it!  I shuffled the screen to show the eastern horizon, and there was Uranus!

This means that for a few days either side of October 18, ALL 8 planets, PLUS the Moon and Pluto will all be visible in the sky simultaneously!  All be it for only a few minutes, but all the major bodies in our solar system will all be visible at one time, and visible telescopically all within a couple of hours after sunset.  And from what I've been able to gather, this event has been totally missed by all major astronomical organizations.

This is an extremely rare event.  With the current position of the planets in their orbits, this whole of solar system event will occur on three separate occasions:

1st event will happen mid-October this year just after sunset, 2018.

2nd event will happen late April next year, 2019, just before sunrise

3rd event will happen late October and into early November next year, 2019, again just after sunset.

Then that's it for a few hundred years!

This alignment sees all the planets lined up all along the ecliptic from the eastern horizon all the way across to the western horizon.  The "ecliptic" is the plane around which all the planets travel in their orbits around the Sun.  Unfortunately this whole of solar system apparition will only last for a few minutes during each day that it is visible due to the position of the planets in their orbits.

Below are two screenshots from the Sky Safari app of the October 2018 event, with the location being from my home here in Sydney.  Please note that the screenshots below are for SYDNEY.  You will need to make the necessary adjustments for time immediately after sunset for your location.


Looking East on October 18 at 7:57pm

Looking West on October 18 at 7:57pm


Below is an image showing the relative positions of the planets at this time when viewed from above the ecliptic.





A linear alignment of all the planets and Pluto does occasionally happen, but with mean hundreds of years between events.  This linear alignment doesn't have all the planets perfect aligned, but the tightest clustering of the planets sees them spread out across 30° from the Sun.  The next such linear alignment isn't expected until the year 2854.

I will be endevouring to make a special occasion of this.  I'll be trying to organize some of my friends to join me with a few scopes to put on a planetary marathon, or a "Solar System Sprint" to bag all the major bodies in our solar system as quickly as possible, and to show all of these bodies to the general public.  I now have a reason to make an effort to chase down Pluto as well!  Prior to knowing about this event I've never had any interest to try to identify Pluto.  After all, it will only appear as a faint star in a field of other faint stars.  This very rare even now changes all of this!  I'll be starting to make observations with my 17.5" dob on a monthly basis of the area that Pluto sits in in order to pinpoint it by its movement against the background stars.  I'll also be doing this photographically from home as I doubt I'll be able to spot Pluto from my home because of light pollution.  It won't stop me from trying though.  I've already identified a magnitude 14 star that is easy to identify, and I have already pinned it with my video astronomy rig from home.  So I know Pluto with within reach of my video astronomy gear from my home.  If I am able to spot this same star with my 17.5" dob, then I know that Pluto is cooked!

Now, fingers crossed for a clear clear night some time on these dates!



Hopefully, you will be able to also enjoy this unique celestial event and attempt your own Solar System Sprint!

Alex.