Transit of Mercury

Text and photos by Ernie Jacobs, Head astronomer

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Viewing our star and its first planet from the third planet! Several telescopes setup at Penn Dixie to view and capture the images of the May 9th Transit of Mercury.

On May 9th 2016 about 120 people took advantage of the opportunity and the fantastic weather to view the Transit of Mercury. During this event, the solar system’s smallest planet crossed the face of the Sun from our point of view here on Earth. Mercury made a crisp, perfectly round, and completely black image against the bright surface of the Sun, in markd contrast to the irregular and fuzzy sunspots also visible on the surface of the Sun at the same time. The site was open for the event from 7 AM thru 3 PM. We had 3 astronomers available with 6 scopes set up viewing of the event. About 32 guests and 60 3rd graders along with 30 Teachers/Chaperones from Buffalo Public School # 81 were on hand to witness the event.

So exactly what is a Transit? An astronomical transit is when one celestial body like a planet or a moon appears to move across the face of another celestial body, like a star for example, as seen from observer on a particular vantage point (in our case, on Earth). So from our perspective here on Earth, only the planets Mercury & Venus and the Moon can transit the Sun. When the moon passes across the face of Sun we call that a Solar Eclipse. In this case Mercury, the solar system’s smallest planet and the closest planet to the Sun, passed in front of the Sun from 7:12 AM EST to 2:42 PM EST and was visible to observers in the eastern United States and Western Europe. Mercury appeared as tiny black dot 10 arcseconds wide moving across the face of the Sun (about 1/200th the width of the Sun). If Mercury was the same size as the Earth, the tiny dot would only appear 2.6 times larger as it traveled across the face of the Sun.

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Cropped image of Mercury during the Transit captured by Jim Maroney on his 8″ Celestron Edge HD with CCD camera. Multiple images were captured and stacked in special software to create this image.

How rare are Transits of Mercury? Transits of Mercury occur about 13 or 14 times per century, so they are rare, but nearly as rare as Transits of Venus. The last transit of Mercury was in 2006 and the next one will occur on November 11, 2019. By contrast the next Transit of Venus, which last occurred in 2012, won’t happen until 2117. The 2019 Transit of Mercury will again be visible in the Americas and Europe.

Were any pictures taken? In addition to viewing the event visually thru telescopes with special solar filters. (Never look at the Sun without following the proper precautions!!!) Images of the event were captured. Photos and videos were captured via smartphones thru the eyepiece of on of the telescopes and Jim Maroney (Penn Dixie’s resident astrophotographer) had multiple telescopes setup to capture the event. We even managed to broadcast the transit live on our Facebook page for a few minutes until the battery in my iPhone was completely drained.

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Ernie Jacobs captured this image of the event using an iPhone, 8″ Dobsonian Telescope, and a 25 mm Plossl eyepiece. A short video was captured on the iPhone. Software broke the video up into individual images, aligned the images, sorted them for quality, and then stacked the highest quality images to create the final image above.

Did I mention the weather was fantastic?  We couldn’t have asked for a better day, hardly a cloud in the sky.  Clearly as an astronomer, I am better suited for observing at night.  Yes, I spent the whole day outside observing the Sun without putting on any sunscreen, Ouch!

All in all it was a spectacular day.  Thanks to my fellow astronomers Rich Switzer and Jim Maroney for sharing their time and expertise and thanks to the volunteers and staff that helped organize and run the event. Clear Skies!

Ernie Jacobs


Additional images of the transit from Jim Maroney, Astrophotographer 

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