Methods of animation

 

Readers of my previous blogs will know that planetary imaging is my passion and in particular creating animations.

I’d like to share with you three different ways I use to show movement on another world using fairly modest equipment (in my case an 8-inch Schmidt-Cassegrain telescope and a planetary imaging camera).

In image editing software it’s easy to create an animated file called a GIF out of a series of images. We’ve covered the procedure in Sky at Night Magazine before, most recently in issue 81, February 2012, the animation portion from this feature can be read on our website here: http://www.skyatnightmagazine.com/image-processing/animation-processing

Jupiter is the easiest planet to make animations of as it has a lot of detail on its surface and it rotates quite quickly. These animations were made in 2011 when it reached opposition (when it’s exactly opposite the Sun in the sky) at almost the same time as it reached perihelion (when it reaches its closest point to the Sun). In addition, it climbed very high in the sky, reaching almost 50º. In astro imaging terms, this was a dream situation with a large disc sitting high above the murky and turbulent lower sky.

So the first and easiest type of animation you can make is a rotation.

THE ROTATION MOVIE

Jupiter rotates in just under 10 hours, so in one night if you photograph it every few minutes for even a short period, you can create a very obvious rotation movie by putting all your images together in photo editing software.

The animation below shows just 40 minutes of rotation but it also reveals a staggering amount of detail. These rotation movies are great at showing exactly which features are real and which are camera artefacts. You can also sometimes capture its moons passing in front of and behind the planet, as can be seen in one of my previous blogs.

40 minutes of rotation, once all the frames had been assembled they were duplicated and reversed, then added to the end so the gif would rotate in both directions

 

THE SURFACE DETAIL MOVIE

The second type of animation is to try and show the movement of cloud formations on the planet. This is much trickier and more time-consuming. The best way to do it is to capture the planet as many times as possible when the Great Red Spot (GRS) is on the central meridian.

That way you can show how the cloud features move around it and you have a large anchor point for the eye. With just three such images taken at three-week intervals, I created the animation below. You can clearly see how the barges (dark elongated clouds) move in the northern equatorial belt, along with a build up of white cloud around the GRS.

Cloud movements on Jupiter over 9 weeks. An animation method known as tweening was used to make the transition between the frames smoother

 

THE RELATIVE SIZE MOVIE

The third animation type is a time-lapse movie showing the planet growing in size as it approaches Earth.

By photographing it regularly (weather permitting) you can clearly show how the disc grows over time as it moves closer to Earth. Of course, the golden rule with this is to always photograph it at the same magnification. I use a 2x Barlow for each image. The animation below shows the planet from 19 August to 20 October 2011.

Jupiter grows in size as it approaches opposition. The use of tweening once again helped the smooth growth effect I wanted from this type of animation

 

Each method takes a lot of patience and perseverance but the results really are wondrous when you consider that you can create moving images of another planet with your own equipment.

I bet when Galileo first looked at Jupiter 400 years ago – seeing something similar to what we now see through our finderscopes – he could never have imagined that one day we’d be able to film it moving from our own back gardens. Makes you wonder what will be possible in another 400 years!

Steve Marsh

Art Editor, Sky at Night Magazine

 

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