After May 9, 2016, Next Mercury Solar Transit Happens November 2019

Summary: After Monday, May 9, 2016, the next Mercury solar transit happens November 2019.

Monday, May 9, 2016, Mercury solar transit, 11:35:47 Coordinated Universal Time (7:35 a.m. Eastern Daylight Time); NASA’s Solar Dynamics Observatory image taken in wavelength of extreme ultraviolet light: NASA Solar Dynamics Observatory, Public Domain, via NASA Goddard Space Flight Center’s Solar Dynamics Observatory

After Mercury’s Monday, May 9, 2016, orbital passage across the sun’s face, the next Mercury solar transit happens November 2019, on the U.S. official public holiday of Veterans Day.

The Monday, May 9, 2016, Mercury solar transit, taking place from 11:12 to 18:42 Coordinated Universal Time (7:12 a.m. to 2:42 p.m. Eastern Daylight Time), ranks as the third Mercury solar transit in the 21st century. The present century, spanning Jan. 1, 2001, to Dec. 31, 2100, experiences 14 Mercury solar transits.

After the May 2016 event, the next Mercury solar transit takes place Monday, Nov. 11. The November 2019 transit begins at 12:35 UTC and lasts for 5 hours 29 minutes.

Times of five critical instants register Mercury’s progress relative to the sun, as observed from Earth. Two pairs of contact parameters frame a central point, known as the greatest transit.

Contact I signals the beginning of the transit as Mercury’s black disk appears adjacent to the solar disk. The November 2019 Mercury solar transit starts at 12:35 UTC (7:35 a.m. EST), with Mercury in external tangency with the sun. The planetary disk's leading edge touches the sun's outer limb, or edge.

Contact II marks the planetary disk’s placement in internal tangency with the solar limb. Contact II occurs at 12:37 UTC (7:37 a.m. EST). Having crossed the sun’s outside edge, the planetary disk displays snug placement of its trailing edge against the sun’s inner limb,  against the full backdrop of the solar disk.

Greatest transit indicates the event’s midpoint, occurring at Mercury’s closest reach of the sun’s center as seen from Earth’s center. Greatest transit in November 2019 takes place at 15:20 UTC (10:20 a.m. EST).

Contact III register’s Mercury’s arrival at the sun’s opposite limb. The planetary disk’s leading edge is internally tangent to the sun’s inner limb. Contact III happens at 18:02 UTC (1:02 p.m. EST).

Contact IV marks the instant of Mercury’s external tangency with the sun. The planetary disk’s trailing edge is adjacent to the solar disk’s outer limb. Contact IV occurs at 18:04 UTC (1:02 p.m. EST).

Mercury’s November 2019 solar transit is 2 hours 1 minute shorter than the planet’s May 2016 transit duration of seven and one-half hours. May transits are longer than November transits because Mercury’s placement is about a month after orbital aphelion, or farthest center-to-center distance from the sun. Planetary velocity decreases around aphelion. Mercury has an aphelic orbital velocity of 38.9 kilometers per second.

November transits are faster than May transits because Mercury is a few days away from orbital perihelion, or closest center-to-center distance to the sun. Planetary velocity increases around perihelion. Mercury has a perihelic orbital velocity of 59.0 kilometers per second.

In addition to their shorter duration, November transits are also more common than May transits. In his catalog of Mercury transits from 1601 to 2300 CE (Common Era) on NASA’s Eclipse Web Site, NASA astrophysicist Fred Espenak explains that November claims 63 of the seven centuries’ total of 94 Mercury solar transits. Only 31, representing one-third of the total, fall in May.

Of the 14 Mercury solar transits occurring in the 21st century, nine fall in November. May claims the century’s first Mercury solar transit, taking place Wednesday, May 7, 2003, from 05:13 UTC (1:13 a.m. EDT) to 10:32 UTC (6:32 a.m. EDT). November claims the century’s last Mercury solar transit, happening Nov. 10, 2098, from 04:35 UTC (11:35 p.m. EST) to 09:57 UTC (4:57 a.m. EST).

The takeaway for the next Mercury solar transit’s November 2019 occurrence is that Mercury’s solar transits happen in one of two months, with November transits taking place more often and faster than May transits.

Earth's orientation during Mercury's solar transit November 2019: Tomruen, CC BY SA 4.0, via Wikimedia Commons

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Monday, May 9, 2016, Mercury solar transit, 11:35:47 Coordinated Universal Time (7:35 a.m. Eastern Daylight Time); NASA’s Solar Dynamics Observatory image taken in wavelength of extreme ultraviolet light: NASA Solar Dynamics Observatory, Public Domain, via NASA Goddard Space Flight Center’s Solar Dynamics Observatory @ http://sdo.gsfc.nasa.gov/gallery/potw/item/713

Earth's orientation during Mercury's solar transit November 2019: Tomruen, CC BY SA 4.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Transit_of_Mercury_November_11_2019_Orientation_of_Earth.png

For further information:

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