Mercury’s Journey Across the Sun

I did this back in 2012 with Venus. Now, what will probably be the last chance in the United States in what’s left of my lifetime, another transit will occur this coming Monday (November 11, 2019) morning when the planet Mercury crosses between Earth and the Sun.

One would think that this sort of thing happens a lot. Since both Mercury and Venus orbit closer to the Sun than Earth, they pass between all the time, right? The problem is that planets don’t orbit in perfectly the same orbital plane (tilted circle). Mercury’s orbit is inclined from that of Earth’s by about 7% which is more than enough, across such vast distances, to cause it to appear either above or below the sun from our perspective much of the time. Plus, it has to pass between Earth and the Sun during the day in your local timezone for you to see it, and it moves across pretty doggon fast.

The next time it transits the Sun for U.S. observers will be in about 30 years.

This time, I’ll bring my telescope to work and set it up in a dark room to project the image more clearly. We have a place on the East side of the building where I can do that.

My 2012 Venus transit setup.

You could do something similar. note that such a setup will display the event upside down or backwards or something…I can’t remember which.

But please, and I can’t stress this enough, be safe. Looking directly at the Sun for any amount of time will damage your eyesite…even through sunglasses. The way I do it, as shown above, is I use a cheap $100 reflector telescope with the eyepiece removed and aim the peephole at a piece of posterboard. Those with more expensive telescopes might have special filters for solar viewing and photography.

A pinhole camera like what I wrote about here after the eclipse might also work. Solar glasses from the eclipse, if you still have them, would let you look at the Sun safely while setting up your equipment. However, I’m not sure that you’ll be able to see a Mercury transit that way, since I have never seen sunspots clearly through solar glasses and Mercury is so viny and distant that it will be smaller than a sunspot. If in doubt (or under cloudy skies) then go back indoors and just stream it live on YouTube. I would not be surprised if NASA TV covers it with satellite imagery…which would be a more spectacular view of the event than anything you or I could ever concoct with our own equipment.

~ by Bill Housley on November 9, 2019.

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