Saturday, 12 May 2018

Jupiter - transit of Europa and its shadow animation

Hello everyone,

The day following my Jupiter sketch I revisited Jup’ and saw the last few minutes of the shadow transit of Io.  With this being essentially the time of Jupiter’s opposition, the gap between Io and its shadow on Jupiter’s disk is just about nil.  As a result it is actually very easy to spot Io against the disk of Jupiter when it is very close to the limb.  This really excite me, and I was keen to sketch the event when it repeated itself.

A couple of nights later (poor seeing conditions prevented any possible sketching), Europa was to transit across Jupiter along with its shadow.  The passing of just four nights was already enough to make the gap between the satellite and its shadow larger, but the effect was really just as intense and fantastic.

 As the transit of Europa started, it occurred to me that I could possibly do an animation of the event out of a series of sketches.  So, two and a bit hours later, I had a completed a sketch with the necessary details and time points that would allow me to prepare a series of twelve individual colour pencil sketches.

Below is the complete series of individual sketches from which the animation was made.

Normally for a high magnification sketch I would have used my 8” SCT.  This time however I used my 8” f/4 Kulali push-pull dob.  Its action is so smooth and easy that following an object at high magnification is very easy.

Object:  Jupiter with transit of Europa and its shadow
Scope:  8” f/4 Kulali push-pull dob
Gear:  5mm TMB Planetary Type II, 160X
Date:  9th May, 2018, 21:10 to 23:20 AET
Location:  Sydney, Australia

Thanks for looking,


Saturday, 5 May 2018

Jupiter - good conditions and a newer scope reveals remarkable detail

Hello everyone,

Well, after so long, I’ve managed reasonable seeing conditions to attempt a sketch of Jupiter.  Last year was a complete non-event with Jupiter as no matter when I looked at Jupiter, seeing was just terrible.  In fact, I haven’t managed a sketch of Jupiter in many years.

I do have to say that one big part of this was due to the old orange tube C8 I was using at the time just wasn’t up to the task.  In terms of focus, that old scope was remarkable and outstanding.  But she didn’t have coated optics, and being close to 40 years old, the optics were not as reflective as when new.  With the Moon this wasn’t an issue, but for planetary detail she wasn’t the best tool for the job.  The new SCT I’m now using, well, there is a big difference!  I am fortunate that the optics are also very good with this new unit, and I can pull outstanding detail with it at high magnification, but the optics are multicoated, and this has made an enormous difference for planetary detail and with DSO’s.

Well, it was good to have a break in the poor seeing and have the opportunity to not only pin Jupiter, but to also try a few illustration techniques I’ve been wanting to have a go with.

As with all my sketching, the longer I spend on a target, the more and more I see as time goes on.  Jupiter was no exception.  As clear seeing windows wafted through, these details revealed themselves as festoons, smaller pressure cells within the two main belts, a mottled structure within the fine bands, subtle colour variations within all the band structures, and most staggering of all was the significant hue difference and structural differences between the two main belts – something that I hadn’t noticed in photographs.  I've also noted the position of the four Galilean moons with just the first letter of the name of each.

Again, the best eyepiece for the night was my modest 9mm TMB Planetary Type II.  My 8mm LVW was just too much grunt, and the TMB just gave a longer and more frequent detail sweet spot as seeing came and went.  I also use two colour filters to help tease out details, a #80A blue and a #8 yellow.  The blue was excellent to tease out the Great Red Spot and the fine cloud banding. The yellow was especially helpful in highlighting the hue differences between the two main cloud bands and the subtle colour variations between the fine bands too.

The sketch at the scope was carried out using a good old graphite pencil on white paper, with a few notes added.  In the light of day I redid the sketch using a variety of coloured pencils on fine white paper – the fine texture paper is important in order to control the scratchy appearance drawing onto paper can have.  Once I was happy with the colour sketch, I cut out the disk and stuck it onto a sheet of the black paper I use for sketching the Moon, Sun and DSO’s.  I think I may need to improve my scissor cutting skills a little! LOL J  I am very happy with the final sketch construct as it gives a better rendition of what is seen through the eyepiece.

Thanks for viewing this piece of mine.


Object:  Jupiter
Scope:  8” SCT
Gear:  9mm TMB, 222X, #80A blue and #8 yellow filters
Date:  4th May, 2018 14:00hrs UTC
Location:  Sydney,  Australia
Media:  Colour and graphite pencils on fine white paper, cut out and stuck onto black A4 size paper.

Crater Humboldt - still so much to learn!

Hi all,

My golly josh!  It has been some 5 months since my last lunar sketch!  This summer has been terrible with astro weather.  Finally there’s been a break in the weather!  Woohoo!

I’ve been wanting to sketch the eastern limb of the Moon from just after the full Moon phase for a very long time.  It is really the only opportunity to sketch features that otherwise are only visible very soon after the New Moon phase, which is not practical being too close to the Sun and the sky is still too bright for good contrast in the image.  On this occasion, the phase was just one day after Full Moon.

It was like looking at the Moon for the very first time!  The whole eastern limb of the Moon is packed full of features that I hadn’t seen before!  It was quite a revelation for me to find out that there was a whole section of the Moon that I was totally unfamiliar with.

This night I took a different approach on what to select to sketch as I couldn’t decide between three or four different areas.   One particular big crater caught my attention, Humboldt.  What most caught my attention is the curious set of central peaks.  So, I looked up Humboldt on the net, and was met with a staggering image from the Lunar Reconnaissance Orbiter – the floor of Humboldt is riddled with a most regular lacy pattern network of riles.  I have never seen such a regular pattern in any crater.  Along with the curious set of central peaks, I was sold on Humboldt as being the center piece of my first lunar sketch in several months.

I was rusty, very rusty to start with.  Not having sketched the Moon for so long, I struggled a little at first to find my grove with the foreshortening and then the shading.  But I persisted and eventually things started to flow and happen a lot more easily.

I found this area quite intriguing.  Humboldt itself is an extremely old feature, yet it’s somehow managed to avoid too much damage over the eons.  Quite remarkable really considering its location so close to the far side of the Moon that has taken the lion’s share of impacts.  Being so close to the limb, and with the terminator just creeping away from the limb, the shadows of the craters, mountains, lone peaks and ridges all made for an outstanding scene and composition to tackle.

While researching this crater after completing the sketch, I came across the site for the Lunar Reconnaissance Orbiter.  The site contains some very high resolution images of Humboldt along with an explanation for the cause of very curious pattern of riles.  As it turns out, these are fracture lines caused by the subterranean magma pressure causing the floor of Humboldt to dome.  From the LROC photograph below, one can see that the pattern of fracture lines is of-center to the geometric center of Humboldt.  This is because the crown of the dome is not centered either.

LROC image.

This sketch was a lovely way to blow the cobwebs out and get back into the grove of some sketching.  Fingers crossed it won’t be another five months until the next!

Object:  Crater Humboldt and surrounds
Telescope:  8” SCT
Gear:  9mm TMB, 222X
Date:  1st May, 2018
Location:  Sydney, Australia

Until next time,

Clear skies and sharp pencils,