Tales From Under the Starry Sky – Week 1

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During these times, as we find ourselves distanced from family and friends, we have all had to adapt to a new way of life, with some strange new customs and unfamiliar activities.  And when there are so many more pressing and troubling matters that each of us has to deal with it seems trite to focus on a mere hobby.  And yet, my time at the telescope has always been a salve for me, lifting me from daily worries and giving me a few minutes or hours of respite.  This may be a strange, new world around us, but it remains a familiar and friendly sky above us.  Our old friends are still there, and still offer the same pleasures, peace and wonder that they always have.

So I have been thinking back to those times under the sky (and looking forward to more) and have pondered on some of my favourite observations over the years; those special moments that stand out above the others.  Sights that, after all this time, are still burned in my memory. 
Each comes with a story, each with a special set of circumstances, and sometimes it is just that, the tale itself, that makes it special. 
This is something that we all have in common; we all have a favourite.  Whether you have been doing this for 50 years or are brand new to the hobby, there is something that stands out, something that comes immediately to mind.  We all have a favourite to think on; we all have a story to tell.
Send in your stories, and each week I’ll include one or two in an email just like this one.  Maybe it’s with your telescope, or binoculars or with the unaided eye.  The story might be long or short, funny or not, alone or with others.  It doesn’t matter; it’s your story.
Maybe we can’t get together right now, and maybe this isn’t how we would ideally like to interact, but we can adapt.  We can stay in touch.   And we can imagine sitting together, sipping a hot drink, telling stories, and laughing with friends. 
I’ll go first.

Ok, so this is proving to be a lot harder than I thought.  Not because I can’t come up with a story, but because there are so many!  How do I whittle it down to just one?

Racing across two different States to get to the centre line of an eclipse in time (the very definition of eclipse chasing)?  Seeing Valles Marineris on Mars?  Or a comet crash into Jupiter?  Pulling the car over to the side of the road to get out and watch an all-sky display of aurora?  Comet Hyakutake spanning the northern sky?  Or simply my very first look through a telescope.  Like so many, the first thing I saw through a telescope was Saturn, and I was hooked.

Ok, I got one.  It’s a Saturn story, but not the one I just mentioned.  It was 1989…

An occultation is when one celestial object passes in front of another.  It happens with the Moon quite a lot.  As it moves in its orbit around Earth is passes in front of, and temporarily hides, background stars.  Sometimes even a pretty bright one.  But a more distant planet, like Saturn, hides stars much less frequently, simply because the planets are much farther away and so look much smaller to us.

On the night of July 2nd, or really the morning of July 3rd 1989, Saturn passed in front of a 5th magnitude star called 28 Sagittarii. 

That night I observed with many other fellow amateurs for what we hoped would be an interesting sight.  I had my 4.25” reflector to look through.  It was my first telescope and I got it as a young teenager with my own money, having saved up.  I was fortunate in that it was very good optically, even if it was a little cumbersome to use on its very heavy equatorial mount.  Over the years I had many wonderful nights with that scope and I remember it fondly.  Eventually, long after it had been replaced with a better one, I passed it on to the teenage son of a co-worker, where I hope it found a second life (well, third, since I got it second hand myself).

If it were the moon occulting this distant star it would simply cover it up and in a moment the star would be gone.  But Saturn is a gas giant, so as the star passed behind it the upper atmosphere of Saturn would, we hoped, gradually obscure the star so that it would appear to fade slowly.  But even better, the star first had to pass behind the rings.  How would that look?  Could we see it shine through the Cassini gap?  Maybe even the Encke gap!?  We really didn’t know what to expect.  Here, courtesy of NASA, is a diagram of the expected path of Saturn in front of the star:

28 Sagittarii is a magnitude 5.4 red giant. That means the star is actually bright enough to see with the unaided eye from a dark site.  Through the telescope the star was easily visible next to Saturn, outshining any of its moons.  In the dark there was quite a bit of chatter between us all, comparing views and speculating on what we would see.  Even though these were the days before the HAA was formed there were other future HAA members there, as well as others from the club I was in at the time.  Some had tape recorders to shout into as different parts of the occultation occurred.  With a radio signal ticking away in the background we could time the events of the night.

Saturn has several major rings, all formed from many smaller ringlets, and those composed of ring particles; millions of pieces of rock and ice all in orbit around Saturn.  The major rings, named for letters of the alphabet, are discernable through amateur scopes.  As the star approached the A ring on the outside is shone steadily and then passed behind the ring.  It was gone!  Then it was back, and then it was gone again!  Dimly, it came and went, on and off, as it passed behind ringlets or large ring particles.  Mostly it was visible the whole time, but dimmed and brightened now and then.  One of the brightest times must have been when it shone through the Encke Gap, but I couldn’t discern the gap in my small scope.  Then it shone brightly through the Cassini Division, seeming so bright after being dimmed by the rings, and then was gone again!
Here is a great illustration by Joe Bergeron that I found online, showing it just as the star shone through the Cassini division.  This is very close to how I remember it;

After passing through the Cassini Gap it was behind the B ring and I couldn’t see it at all.  These handful of minutes was a bit of a break but it was so hard to tear away from the eyepiece.  And then the star emerged from the B ring and passed behind the C ring.  This was the best show of all as you could see the star flickering on and off.  Constantly flickering, that’s the best way I can describe it.  We were awestruck!  We were actually seeing with our eyes the proof of the fine structure of the rings.  What usually shows itself as broad constructs, the A and B rings, and on a good night the C ring, were now a completely different thing, full of structure and detail.  I was amazed.

Finally it approached the body of Saturn itself.  I know it was a trick of the eye, much like the teardrop effect when Mercury or Venus pass in front of the limb of the Sun during a transit, but it really did look like the star was shining through the limb of the planet.  It faded slowly as denser gasses obscured it, and then it was finally gone.

Well, the night wasn’t over.  There was lots of talking and comparing notes and views.  Lots of “Did you see this” and “Did you see that?”!  I didn’t see 28 Sag emerge from the other side of Saturn; they were setting and the dawn was coming.  That view was reserved for those living on the west coast.  But it didn’t matter; I was more than satisfied.  Saturn and this distant star had put on a show that exceeded my hopes.  Indeed, more than 30 years later, it remains vivid in my memory and here I am telling the tale.

Ok, that’s one of my stories.  Thanks for hanging in there with me.  Now it’s your turn.  Tell us one of your stories.  It doesn’t have to be as long as this one, but you know me; once I get going…
Send me an email at chair@amateurastronomy.org with your favourite observation and I’ll share it with the club.  Be the star of a future weekly email.  Tell the next Tale from Under the Starry Sky.

John Gauvreau