Students Observe the Mercury Transit

On Monday, May 9, 2016, close to 100 students from grades 7 thru 12 walked into the Kohout-Dingley Observatory located on the Sacred Heart High School campus to safely view the rare transit of the planet Mercury crossing the disk of the Sun. This was the first use of the new Baader solar filter manufactured by AstroZap recently purchased specifically for the event. The session, in partnership with the staff of Insight Observatory, hosted entire classes throughout the course of the school day as well as small groups of students visiting during their lunch session. All observers were treated not only to the Mercury transit event but were able to observe groups of sunspots as well.

Sacred Heart Students Observing the Mercury Transit - Photo by Joe Masi.

The early morning hours of May, 9th brought a potential promise of clear observing conditions for the transit. However, just as I was leaving for the observatory to set up for the day, clouds started quickly rolling in. I checked in with the transit's live coverage feed from Sky and Telescope Magazine and J. Kelly Beatty, one of the publication's Chief Editors, was reporting the same weather conditions from Cambridge, Massachusetts. Once I arrived at the school's campus around 8:10 am located in Kingston, Massachusetts, I noticed the clouds were starting to break up and scatter a bit. Joe Masi, a science teacher at the school, assisted me with opening the facility that houses the 11" Celestron Schmidt-Cassegrain Telescope. As the sky proceeded to clear up, we locked the solar filter onto place on the telescope and proceeded to slew the telescope towards the Sun. Remember, NEVER look directly at the Sun find it. As I focused the telescope I immediately detected a defined sharp black dot on the Sun's disk along with a few small groupings of sunspots. Mr. Masi wanted to get a quick peek before his 9:00 am class started. He quickly spotted the tiny planet as well.

A little after 9:00 am, Mr. Masi returned to the observatory with his first class. As the students in groups of 2 or 3 took turns viewing the Mercury transit upstairs at the telescope, the rest of the class below learned about the event taking place with a display set up by Insight Observatory on the first floor. The science teachers were discussing what was actually transpiring as well by using the display as an aide. While Mr. Masi's first class was enjoying the event, he suggested that the students image the transit on their smartphones. Some of the students attempted this throughout the day (as I did myself). However, it was very painstaking trying to hold the device steady enough to get an image in decent focus. A student from the first class, Nolan D., had the most successful image of the day. The morning classes that visited the observatory were treated to excellent views of the transit as the sky completely cleared up. However, the students that stopped by during their lunch period were challenged by fast-moving clouds. As they patiently waited, they were able to get a quick glimpse.

Mercury Transit at 9:15 am EDT - Image by Nolan D.

After the last class left around 2:10 pm, I sat in the observing chair at the telescope and took in the last part of this rare event. I watched the silhouette of the planet slowly disappear at the sun's limb exactly at 2:41 pm EDT. It was a great astronomy education experience and a pleasure in sharing the transit of Mercury with the Sacred Heart students. Some of them are already looking forward to the next one in November 2019.

Special thanks to Frank Lopez of the Stellarvision Astronomy and Science Shop located in Tucson, Arizona for his prompt delivery of the AstroZap Solar Filter allowing us to observe this special event.

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May 9th 2016 Transit of Mercury

On Monday, May 9th, 2016, a transit of the planet Mercury will take place. The tiny planet will travel across the face of the Sun. Mercury transits are rare events that can be observed from much of the world, however, since they involve viewing the Sun, extreme caution must be taken when attempting to observe them. NEVER look directly at the sun with the unaided eye, binoculars, or telescopes unless they are equipped with special solar filters and supervised by an educator or experienced amateur astronomer. One of the easiest and safest ways to observe this rare event is online via a live web feed. Insight Observatory will be broadcasting a live web of the transit courtesy of Sky and Telescope Magazine's Livestream channel. You can watch the progress of the planet Mercury crossing the Sun's disc on our website at http://www.insightobservatory.com/p/real-time-astronomical-event.html.

Sky and Telescope Magazine Diagram.

During this transit, the planet Mercury is seen as a tiny black dot moving slowly in an East-to-West direction across the Sun. The 2016 transit begins on May 9th at 11:12 UT (Universal Time, which is equivalent to Greenwich Mean Time) and ends later that same day at 18:42 UT, with mid-transit taking place at 14:57 UT. Here in the northeast, the event begins at 7:22 am with the transiting midpoint at 10:57 am and ending at 2:42 pm. If you’re in western North America, the rising Sun will already display Mercury’s black dot. Easterners and many Western Europeans will be able to watch the entire transit, weather permitting, from Mercury’s first sign of visibility onto the Sun’s face to its final disappearance 7½ hours later.

For the rest of Europe, Africa, and most of Asia, the transit also begins in the daytime but will still be underway when the Sunsets. Observers in Australia and eastern Asia will just have to watch online as it will not be visible to those parts of the globe. For more detailed information on of the Mercury transit, please visit Sky and Telescope's article covering the event.

Mercury is the smallest planet, therefore, you'll need a telescope to observe its transit. The black silhouette will appear only 12 arcseconds wide even though Mercury is at inferior conjunction. That’s about 1⁄160 of the Sun’s width and only a fifth the diameter (and 4% of the area) of Venus’s dramatic black disk during the rare transits of Venus. When first viewing, you might mistake Mercury for a small sunspot. It’s precisely round and lacks a gray penumbra. As Mercury travels across the Sun’s vast expanse, how readily can you see its motion? If it passes near a sunspot, can you see that it’s darker than even the sunspot’s umbra? When Mercury departs at egress, the sequence of phenomena at ingress unwinds in reverse order.

Image from In-The-Sky.org

After a May transit, a November transit always occurs 3.5 years later (for instance: May 9, 2016, and November 11, 2019). Transits recur on nearly the same date in cycles of 46 years (for instance: May 9, 2016, and May 10, 2062). November transits, which are more common than May transits, occasionally recur in periods of 7 years, and more frequently in periods of 13 and 33 years. If you simply can’t catch 2016’s Mercury madness, make sure to mark your calendar for the next mercury transit on November 11, 2019. After that, you’ll be waiting until 2032.

Sources: Sky and Telescope Magazine, NakedEyePlanets.com

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