Upcoming Mercury Transit

We have a fairly significant astronomical event fast approaching so I've been trying to get ready for it in case, by some miracle, we have clear skies here.  If we go by statistical data about our climate here on the flats nestled between multiple ski resorts and mountains tells me that the chances that I will have clear skies are relatively slim but I'm hopeful.  On the morning of November 11th, we will have a rare opportunity to watch Mercury transit across the face of the sun.  

Mercury is tiny compared to the size of the sun so this isn't anything that will be noticed with the naked eye but it can be seen through a solar telescope if the sky is clear.  I feel the need to make it crystal clear that you must use a solar telescope and not a typical nighttime telescope unless you want to be painfully blinded.  

The sun is actually 277 times larger than the size of Mercury so Mercury will only appear as a tiny dot silhouetted in front of the sun as it passes between us and the sun.  A safe solar telescope will be necessary to view this event.

Mercury travels around the sun faster than any other planet in our solar system.  It zooms around the sun in only 88 days.  Even though it zips around the sun so often, we only get to witness Mercury transiting across the face of the sun about 13 times each century.  If we miss this upcoming transit on November 11th, we won't get another chance to see it until 2032.  Considering my age and my health, needless to say, I'm hoping for good sky conditions on this November 11th!

My plan is to use two or three different telescopes to image this relatively rare occurrence.  Viewing the sun is very different than viewing the night sky, though, so I need to use specialized solar gear to accomplish this.  I have some gear but having more gear at my disposal is always an added benefit in case something goes awry and something usually does go awry.

I've been told that a solar filter made using Baader Solar Film provides great views so I set out to make a filter using this material.  I took some measurements, did some sketching, and then found some scrap wood in the shed to use to make this filter...

When completed, this filter will slip over the front of one of my telescopes and then clamp down on the front edge of the dew shield.  This meant that I needed two or three rings of plywood to layer...

I glued and clamped the rear part of the filter cell and then went back to work on the front part of the cell as the glue dried on the rear part...

After painting the parts, I tested how they fit together.  It is beginning to look like a filter cell at this point...

Gluing the filter material to the wood filter frame was the most tedious part of this little project.  That filter material is easily damaged and this is something that cannot be damaged if you plan to safely view the powerful sun.  I was able to glue and screw everything together in a couple of hours.  

Unfortunately, we had mostly cloudy skies and the sun was mostly obscured by these clouds so testing was tough.  Hmmm...  actually, to be honest, it was quite frustrating.  The clouds were so thick and widespread that I had a lot of difficulty even finding the sun!  The clouds had diffused the sun's light so much that it wasn't even registering in my solar finder scope. 

Here is a photo of this new homemade solar filter on one of my telescopes...

After viewing and testing on this cloudy day, I am not too pleased with the quality of the image I am getting through this filter.  I was expecting and hoping for more so I'm left a bit disappointed.  

Even with the cloudy conditions, I was able to compare this filter to my Meade solar wedge and my initial impression is that there is no comparison.  The solar wedge is far superior to this filter.  I'm actually really disappointed in the quality of the views through this filter when compared to my solar wedge.  

There is no doubt that, in astronomy, you get what you pay for and this homemade filter was relatively inexpensive.  It was more about effort in designing and building it rather than financial cost.  A manufactured filter would cost double what this cost me and a second solar wedge would cost about six times what this homemade filter cost me financially.  It did, however, cost me in much needed energy though and that is extremely frustrating to someone with little energy to begin with nevermind having some to spare.    

I was so disappointed and frustrated at the end of this day as I cleaned up that I was tempted to impulsively toss this newly built filter into the firepit or trash bin.  Instead, the logical part of my brain prevailed and I carefully slipped it into a gallon size ziplock bag and placed it with the rest of my astronomy gear.  I realized that tossing this homemade filter in the trash before testing it more on another day...  a clear day...  would be a be a bit absurd so I safely tucked it away for another day... 




POST EDIT:  October 15, 2019 - I had a chance to get outside this morning in clear skies to compare this new homemade solar filter to one of my older Spectrum glass solar filters.  

First, let me start with the good news.  The view through my homemade film filter looked better today than it did the other day so that was a good start.  I added some other filters into the optical train today though...  a UV/IR Cut filter and a Solar Continuum filter...  so that may have helped to improve the view.  Things looked a bit better through this homemade solar filter today so that is the good news.

The not-so-good news is that this homemade solar film filter was no better than a Spectrum solar glass filter I have.  I compared them side-by-side and actually, visually, I could not see a difference between the two.  This is not-so-good news because the film filter was supposed to be noticeably crisper and more detailed than when using a glass filter.  I noticed no difference this morning though.  Maybe I have a better-than-average glass solar filter...  or, maybe, the Baader film filters are way overrated.  Since both provided comparable views, I would prefer to have a sturdier glass filter rather than this flimsy film filter material.

Anyway, I'm glad I got out there this morning to play around with these two solar filters.  I feel a bit better about my homemade filter now and I'm glad I didn't impulsively throw it in the firepit or trash bin as I almost did the other day!

Lugging around all this solar astronomy gear from inside to outside about eight times and then back inside in another eight or so trips really wore me out.  I'm exhausted and need to sleep.