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Friday, 7 July 2017

Does Saturn have ears?

This year Jupiter and Saturn are fairly nearby in the sky so just a few weeks after Jupiter went past opposition so did his father.  As this would be the closest approach to Saturn this year (and also its highest position in the sky) I decided to take a picture... and just for a bit of fun I thought I would show you all why Galileo famously described Saturn as "As a planet with ears".

In the top image I used a high frame rate camera recording at 23 frames per second for 3000 frames, I then used software to select the best 300 frames and combine them to allow me to produce a relatively sharp image that clearly shows the rings as distinct from the planet.  You can also see the Cassini division which separates the darker 'A' ring on the outside of the disk from the brighter and wider 'B' ring.  Above the disk of the planet you can make out Saturn's shadow being cast over the rings and conversely where the rings cross the planet you can make out hints of the shadow of the rings cast on to the cloud tops of Saturns atmosphere.

But of course Galileo didn't have a high frame rate camera, or a computer capable of sorting and stacking the frames, he also had no prior knowledge of what he was looking at!  

The lower image is the same as the upper one but blurred to simulate the relatively poor optics and the effect of the atmospheric "seeing" that Galileo might have experienced at the eyepiece.  


The video clip below is an unprocessed export of part of the video I recorded through my telescope, keep in mind that this video clip is much sharper than the view through Galileo's telescope would have been due to the size of my telescope compared to his.  Its not hard to see why he was a bit confused!


video

Saturday, 24 June 2017

Jupiter Posing

Neither of my telescopes are particularly suited to planetary observation, the focal lengths are a bit too short really but sometimes the planets are just to tempting to ignore, especially when they are at "Opposition" (the time in the year when a given planet is opposite the sun in the sky and therefore at its closest approach).  Such was the situation for Jupiter last month so I took this image of the King of the Planets:
I am very pleased with the outcome!

I should point out that this is not a single frame snapshot.   This picture was produced by combining several hundred frames extracted from a video and combined to produce a much sharper image than could ever be achieved with a single frame. 

First and most obvious thing to notice is the colour banding: the equatorial, tropical and temperate bands are all clearly visible along with the "Festoons" which are the the crenelations visible along the contacts between the light and dark bands.  These Festoons are essentially storm systems and occasionally they develop into full blown cyclone storms, the most famous of which is the Great Red Spot which I think is the dark spot in the upper left quadrant of the planet.

Some of you may be thinking that the GRS is in the southern equatorial belt, why is it in the upper section of the planet?  That is because my telescopes invert up and down, so Jupiter's South pole is at the top of the image! It would of course be very easy to flip the image over but I like to preserve the view through the eyepiece :)