Monday, November 11, 2019

The 2019 Transit of Mercury

Though the weather was mostly uncooperative (heavy fog and some clouds to boot) I was able to grab a few images of the transit of Mercury. A transit of the planet Mercury is when the planet moves between us and the Sun, making Mercury look like a black dot on the visible disk of the Sun.

I participated in a nation-wide effort called "The Citizen ToM Project" (ToM=Transit of Mercury) under the direction of Zach Stockbridge. Youtube

The goal was to recreate the experiment proposed by Edmond Halley (the great comet was named after him). He calculated that two people widely spaced on our planet timing the transit of Venus would be able to use basic geometry and calculus to figure out how far the Earth is from the Sun (the "AU" or astronomical unit). He died before he could prove it. After his death, several expeditions were launched (in 1761) to gather the data needed to determine the AU with good success.

My experience that day for the Citizen ToM Project:
The day of the transit started with heavy fog forcing me to travel about 45 miles from my home in La Pine, Oregon into the Oregon Outback. My final location was Fort Rock State Park, Oregon. I had intended to travel even more south-east to avoid the fog but that direction had even thicker fog. 

In my rush to set up the equipment in the hopes of making an early observation (using the Citizen CATE total solar eclipse project equipment) I forgot to polar align! But no need... I got lucky: my guess-timate was almost dead on! As the Sun would only peak out very occasionally (and even then it was through thinner fog) I found that I only had to barely move the scope as the Sun was always in the camera's field of view! 

I missed most of the early timings but was able to catch the egress of Mercury! Then... nothing but thick clouds over the Sun! It was awesome to have participated in this transit of Mercury experiment! - Richard Lighthill, La Pine, Oregon.



This is image is the first that I was able to make when the fog thinned enough for me to focus clearly:
If you look closely a little up and left of center you will see the dot that is Mercury.

Here is where I was located for these photographs: Fort Rock State Park:

Hours later I was able to catch Mercury
before it egressed from the Sun's disk.
(It is in the upper right quadrant of the Sun.)

Here the planet as it begins to leave the Sun's disk (cropped image)



And then it is gone!

Next time: November 13, 2032!

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