How to capture scientific images of Saturn

Saturn's storms, colour variations and ring spokes are all worth tracking, says The Sky at Night's Pete Lawrence.

Saturn is a major gas planet but the amount of detail it shows through amateur scopes is significantly less than its inner neighbour, Jupiter.

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This is because of the high layer of haze in its atmosphere and its greater distance from the Sun. Consequently Saturn’s atmospheric features are far more subtle in appearance.

Bright spots on its disc represent the presence of Saturnian storms. Observing and recording such events is extremely important and programs such as WinJUPOS can be used to measure their position and track drift.

Occasionally, larger long-lived events, such as the ‘Dragon Storm’ of 2010/11 (a large, bright and complex convective storm in Saturn’s southern hemisphere), break out and appear to spread through many degrees of longitude. 

The use of imaging filters (a red one is being used here) can help improve the visibility of Saturnian phenomena such as the Northern Hemipshere’s polar hexagon. Credit: Pete Lawrence
The use of imaging filters (a red one is being used here) can help improve the visibility of Saturnian phenomena such as the Northern Hemipshere’s polar hexagon. Credit: Pete Lawrence

Frequent imaging is encouraged to help provide a global record of these infrequent events.

In addition to the appearance of storms in Saturn’s atmosphere, the planet also shows a series of belts just like those seen in Jupiter’s atmosphere.

However, unlike the Jovian belts, Saturn’s appear far less prominent and detailed. Despite this, images taken through different filters can provide important information as to how the intensity of the belts changes.

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When Saturn is presented with a high tilt angle, an interesting exercise is to try to record phenomena found at the polar regions, such as the northern hemisphere’s polar hexagon.

Between 2012 and 2016, the hexagon changed from mostly blue to more of a golden colour, so those this is definitely an interesting, dynamic feature for amateur astronomers to chronicle.

Like Jupiter, Saturn’s atmosphere shows numerous belts and zones. Recording variations in their intensity and colour will make valuable contributions to science. Credit: Pete Lawrence
Like Jupiter, Saturn’s atmosphere shows numerous belts and zones. Recording variations in their intensity and colour will make valuable contributions to science. Credit: Pete Lawrence

Of course, a major feature of this beautiful world are its magnificent rings and monitoring them for subtle variations in intensity is another important project for amateur imagers.

The presence and appearance of radial ‘ring spokes’ is of particular interest. Imaged and animated by orbiting spacecraft, this phenomena has been reported by visual observers many times too.

Capturing an animated sequence showing ring spoke movement from Earth would be a very valuable record indeed. 

As with most planets, the use of filters can enhance the contrast of certain features. As ever, it’s important to accurately record the date, time and which filters have been used to produce each image.

Saturn’s rings appear brighter near to opposition than at other times, as this compare and contrast shows. Credit: Pete Lawrence
Saturn’s rings appear brighter near to opposition than at other times, as this compare and contrast shows. Credit: Pete Lawrence

Useful hardware & software

Hardware

  • High-frame-rate cameras
  • RGB imaging filters for use with a mono camera
  • Speciality filters, eg, longpass
  • Filter wheel
  • Atmospheric dispersion corrector
  • Large-aperture, long-focal-length telescope on a driven mount
  • A laptop

Software

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Pete Lawrence is an experienced astrophotographer and a co-presenter on The Sky at Night.