The Saturnian Ring System

 

Images taken of Saturn using the 127mm Meade Apo Refractor at the Jodrell Plank Observatory from 2014 until 2021

" Have you ever been sitting in a railway carriage reading a newspaper and as the train slowly pulled out of the station you cursorily looked out the window? For a moment you might wonder if you in the carriage is moving forward or whether the platform is moving backwards whilst you remain stationary. Living on any planet in a dynamic planetary system has similar associated issues of relative movement.

As an 'Earthling', we can watch our Sun rise in the  East and set in the West just  like clockwork measuring the length of the day and night. Similarly, every midsummer, the Sun at midday is higher in the sky than at midday in midwinter. The former wouldn't happen if the Earth stopped rotating about a North - South axis or if it rotated the other way around, the latter would not occur if the Earth's axis of rotation was perpendicular to it's plane of orbit around the Sun.

For time immemorial, mankind has viewed the night sky and wondered at the constancy of the stars and the constellations.  Our far ancestors did notice that a few stars seemed to move oddly against the backdrop of the constant heavens and these were called  the 'Planets';  Mercury, Venus, Mars, Jupiter and Saturn - 'planete' was the word used by the ancient Greeks to define these 'unusual stars' and literally means 'wanderer'.

Explaining the movement of the planets became a lot simpler for almost everyone, other than the 'Inquisition'', once we came to terms with the uneasy thought that the Earth and/or mankind wasn't at the centre of everything.

If you look closely at the above images of Saturn you will notice two things:

1. The 2021 image is not as sharp as the others from previous years.
2. The angle at which we see the Rings appears to change over time.

The 2021 image is not as sharp because this year Saturn is very low on our southern horizon, which means we are imaging it obliquely through more of  our turbulent and polluted atmosphere. The night we captured this image the air over Lowestoft was particularly volatile making obtaining a sharp focus extremely difficult. Whilst Saturn and Jupiter are currently low to the horizon as viewed from countries in the Northern Hemisphere, from Southern Hemisphere locations both these planets are currently presenting high in the sky. This is because of the Earth's axial inclination to it's orbital plane and its position on its 12 monthly orbit around the Sun. For the same reason, when it's summer in the UK it's winter in New Zealand.

The view of the Rings appears to become less oblique from 2014 to 2017 when they are at their most open and then begin to close such that in 2021 we can just make out the south pole appearing above the Rings. This closing of our view will continue until 2025 when we will view the Ring System edge on. After 2025, the southern Saturnian Hemisphere will experience what passes for Summer on a cold Gas Giant.

In reality the Ring System will not change fundamentally, just the angle at which it is illuminated by the Sun and the angle at which we view it!

Saturnoppositions-animated By <a href="commons.wikimedia.orgwikiUserTdadamemd" title="UserTdadamemd">Tdadamemd<a> - <a href="commons.wikimedia.orgwikiFileSaturnoppositions.jpg" ti

Understanding the meanings of 'ecliptic' and 'equinox' are key to understanding why our view of Saturn and the Saturnian Rings changes over time on a cyclical basis.

Earths_orbit_and_ecliptic By Tfr000 (talk) 0159, 15 March 2012 (UTC) - Own work, CC BY-SA 3.0, httpscommons.wikimedia.orgwindex.phpcurid=18705315

The majority of the major bodies of the Solar System orbit the Sun in nearly the same plane. This is probably due to the way the Solar System formed from a protoplanetary disk of dust and gas. Probably the closest current representation of the disk is called the invariable plane of the Solar System. Earth's orbit, and hence, the ecliptic, is inclined a little more than 1° to the invariable plane, Jupiter's orbit is within a little more than 1⁄2° of it, and the other major planets are all within about 6°. Because of this, most Solar System bodies appear very close to the ecliptic in the sky. If you live in the Northern Hemisphere and you currently look south you will see Saturn leading Jupiter west across the sky.

Saturn's rotational axis like Earth's is inclined at an angle to the ecliptic. The Earth has an inclination of 23.4 degrees and Saturn 26.7 degrees. An equinox occurs when the position of the Sun is directly over the planet's equator. Both Saturn and  Earth have two Equinoxes in their respective years but Saturn's year, its orbital period, takes 29.4571 Earth years. So Saturn's equinoxes occur approximately 15 Earth years apart whilst on our planet they happen every six months.

 

PIA14943-SaturnBehindTheRings-20180813 By NASAJPL-CaltechSpace Science Institute - <a rel="nofollow" class="external free" href="httpsphotojournal.jpl.nasa.govjpegPIA14943.jpg">httpsphotoj

Earlier I wrote that the Ring system will not change 'fundamentally' but it is wise to note that each ring is made from billions of pieces of ice and rock, varying in size from a grain of sand to that of an average house, all of which are constantly on the move. These Rings are thousands of miles wide but only between 10 and 100 metres thick. There are gaps between them which can be seen clearly in the above image taken by the Cassini space probe. If you look at the images captured at the Jodrell Plank Observatory you can  see the A, B and C Rings with the Cassini Division - the black gap between the A and B Rings.  Each Ring is a dynamic system moving and constrained by the influence of gravity, angular momentum and harmonic resonance. We live in a chaotic Universe, so enjoy Saturn's beautiful icy Rings whilst you can. Mankind's span is brief, so much in the Solar System appears constant but over cosmological timescales change is definitely the name of the game.

The Rings were probably formed by Saturn's gravity capturing asteroids, comets and small moons and smashing them up in a series of collisions. How long ago were they formed is still a matter for debate. As a result of findings from the Cassini probe and estimating age from the accumulation of contaminant pollution of the Ring material, some scientists believe the Rings formed fairly recently and within the last 100 million years. Other scientists believe that the Rings are much older and that a natural process of recycling could throw this estimate way off. As Sir Patrick Moore used to say " We will just have to wait and see". - Karl Seguine Community Outreach Coordinator at the Jodrell Plank Observatory.

Saturn's_Rings_PIA03550 By NASAJPL - httpphotojournal.jpl.nasa.govcatalogPIA03550, Public Domain, httpscommons.wikimedia.orgwindex.phpcurid=610237

Saturn's_rings_in_visible_light_and_radio NASA

Saturn and its Moons

 

A compilation widefield images of the gas giant planet Saturn and five of its moons on the 8th of September 2012. Images taken with 127mm Meade Apo Refractor, x3 Barlow lens and a QHY5l-11 colour video camera. Credit: Pip Stakkert.

" Imaging Saturn remains difficult as the planet is very low on our southern horizon in Lowestoft. The location of the moons: Titan, Dione and Rhea was easy to achieve but Tethys and Enceladus, being close and therefore lost in the glare from Saturn, required the position of the moons to be estimated using planetarium software. Saturn is probably one of the most beautiful astronomical objects to be viewed through the eyepiece of a telescope." - Karl Seguine Community Outreach Coordinator at the Jodrell Plank Observatory.

The Great Red Spot 2021

 

The Great Red Spot visible on Jupiter's Disc. 127mm Meade Apo Refractor, x3 Barlow and QHY5L-11 colour camera. 3 minute video clip stacked. Credit Pip Stakkert.

JunoCam on the JUNO Spacecraft: Image processing from RAW download by Pip Stakkert .   Credit for data NASA, JPL, SwRI. 
Mission Phase: PERIJOVE SwRI/35 2021-07-21 08:44 UT

" Our images of Jupiter captured on the 8th of September 2021 show the Great Red Spot, an enormous anticyclone, looking paler and smaller than in previous years. When we look at Jupiter through a telescope we see the turbulent weather systems and clouds reflecting sunlight which takes approximately 77 minutes for the round trip. The cloud systems are in constant movement driven by internal heat and the energy imparted by the planet's high rate of spin. Amongst this metrological chaos the red spot has remained a constant feature. In the last few years the GRS has grown smaller and paler. At the same time, large white ovals or spots have appeared in and around the South Equatorial Belt. Interaction with the white ovals appears to have resulted in the GRS becoming paler and smaller." - Kurt Thrust current Director of the Jodrell Plank Observatory.

Gas Giants in September 2021

 

Jupiter 08-09-2021, Meade 127mm Apo refractor-QHY5L-11c camera - 3minute avi clip stacked. Credit: Pip Stakkert.

Saturn 08-09-2021, Meade 127mm Apo refractor-QHY5L-11c camera - 9 minute avi clip stacked. Credit: Pip Stakkert.

" The weather forecast for the night of the 8th of September was not good but the weather was predicted to deteriorate in the nights following. We therefore decided to give imaging the gas giant planets, Jupiter and Saturn, a go anyway. 

The planets remain low on our southern horizon and there was also a hint of high level cloud both of which made obtaining sharp images problematic. Saturn being the lower of the two planets was wobbling about all over the place and was difficult to focus. The day had been quite hot in Lowestoft and residual heat radiating from adjoining house roofs exacerbated the atmospheric problems. The difference in image quality between Jupiter and Saturn is clear. Jupiter being much closer, bigger and at a greater declination all go to making for a sharper more detailed image.  Over the next few years the planets will get higher in the sky in the Northern Hemisphere.

If you look closely at the image of Jupiter you can just make out the Great Red Spot towards the bottom of the sphere at about '5 o clock' on the planet's limb. You can also see that Jupiter is not a perfect sphere, having a greater diameter measured at the equator than through the poles. Jupiter is an 'oblate spheroid'. This is because Jupiter is made from primarily gas and is rotating at considerable speed. The Jupiter day is only 10 hours long!  Centrifugal force acts upon the gas to increase the diameter at the equator where the speed is maximised." - Kurt Thrust current Director of the Jodrell Plank Observatory.

Mu Serpentis - or is it though?

 

Image acquired with the Star Adventurer mounted 66mm Altair Refractor, the new 500 lines/mm spectrometer and the QHY5-11mono camera. Credit :Jolene McSquint-Fleming.

Calibrated Line Profiles and Reference Profile for an A07 class star together with a stretched coloured Synthetic Spectrum Strip. Credit: Jolene McSquint-Fleming.

New 500 lines/mm spectrometer designed and constructed in the Observatory clean room by Jolene McSquint- Fleming the JPO's Instrumentation Engineer.

"The weather continues to be very unfavorable for astronomy, with high level cloud preventing us imaging the gas giant planets Jupiter and Saturn. 

Over the summer, Jolene has addressed some of the optical aberrations associated with using a 500 line diffraction grating as a simple filter cell.  We did not want to permanently adapt the QHY5-11 camera for spectroscopy and so designed a 3d printed block to allow it to be brought very close to the imaging chip at the optimum angle for a first order spectrum at 550nm. This appears to have minimised 'fish tailing' of the spectral image and aided obtaining focus upon the spectrum rather than the star. 

On the 7th of July 2021 we tried the new spectrometer out using the 66mm Altair Astro refractor.  As the sky was quite light, only a few stars on the meridian were visible to the naked eye, so we chose one at random for the trial.

One of the not immediately appreciable downsides of using a 500 line diffraction grating is that, as the spectrum is more spread out than when using  a 100 or 200 line grating, it produces a significantly dimmer image. Possibly this will be improved by using the 127mm refractor, by stacking more light frames and by taking darks and flats. 

We prepped the spectral image using the freeware IRIS and then had a go at producing an initial calibrated profile using the excellent BASS software. The Observatory is indebted to the generous, skilled and intelligent individuals that devise and collaborate in the development of scientific software which is made accessible for free use. Thank you Christian. B and John. P!

Having obtained a profile we guessed, from the presence of strong Hydrogen Balmer lines, that the star in question is an A type star. We then used Stellarium to look for bright  A type stars that were observable to the naked eye and to the south near the meridian on 07-07-2021. The best candidate  is the A07 star Mu Serpentis.

Next up we intend to:

Image Vega and obtain a camera response curve for the set up.

Become more proficient in the use of BASS software.

Complete a half constructed 3d printed 100 lines/mm spectrometer for obtaining spectra from fainter stars.

Come up with a rudimentary grating design to address extended objects of interest.

Experiment with a fibre-optic link between the telescope and a spectrometer." - Kurt  Thrust current Director of the Jodrell Plank Observatory

Gas Giants over Southwold and night scented honeysuckle.

 

The Gas Giant Planets - Jupiter and Saturn over Southwold, Suffolk. Canon 600d DSLR and Sigma lens at f=10mm and F=4.5. Stack of 3x20sec lights at ISO 3200. Credit: George Hammer Astro-Geologist at the Jodrell Plank Observatory.

Perseid Shower Compilation - Credit Kurt Thrust

" Nice to see the two gas giant planets, Jupiter and Saturn putting on such a good show low to the horizon in the south. We hope to be imaging both of these wonderful planets in the near future using the Jodrell Plank Observatory's 127mm Apo refracting telescope. Of course this is all subject to our adjoining neighbour, Mr. Schrödinger, allowing us to trim back his Lonicera periclymenum Serotina . We keep him on side by looking after his cat over the holidays!". - Joel Cairo CEO of the Jodrell Plank Observatory.

The Perseid Shower 2021 and other assorted meteors

 

A stack compilation of 30x20sec lights taken between 12:30 am and 02:30am on the 13th August 2021. Tripod mounted Canon 600d DSLR with a SIGMA 10-20mm lens at F4.5 and f=10mm. Credit Pip Stakkert.

"The whole Jodrell Plank Team relocated to the cliff top at nearby Pakefield and watched a wonderful show of Perseid and sporadic meteors as they fell over the North Sea. Pip Stakkert made a great effort to capture the magnificence of this year's splendid pyrotechnic display. We were all disappointed by the light pollution from the newly refurbished CEFAS cliff top laboratories and offices. Internal and external lights were on when we arrived and were still blazing away when we left Pakefield at 2;45am. The new LED lighting is very bright across a wide visual spectrum and the external scheme is poorly designed. It is something of a disgrace that a Government building dedicated to protecting the sea and fish stocks has lighting detrimental to the night sky!  A number of the meteors in the above image are clearly Perseids but some are not. The 'fireball' shown on the extreme top left of the image was a spectacular sight to the naked eye." - Kurt Thrust current Director of the Jodrell Plank Observatory.