Saturday, October 5, 2019


Mark your calendar: On Monday, Nov 11th, Mercury will pass directly in front the sun. The rare transit begins at 12:35 UT (7:35 am EST) and lasts for almost six hours. Mercury's tiny form—jet black and perfectly round—will glide slowly across the solar disk, as shown in this movie created by science-artist Larry Koehn of

People in every continent except Australia can see at least a portion of the crossing. In the USA, the best place to be is on the Atlantic coast, where the entire transit is visible. On the Pacific coast the transit will already be in progress at sunrise.
Warning! Do not stare at the sun during the transit. Mercury covers a tiny, tiny fraction of the solar disk, so the sun remains as bright as ever. Eye damage can occur.

Eclipse glasses will keep your eyes safe, but they won't help you see Mercury. The planet is only 1/194th of the sun's apparent diameter. A safely-filtered telescope with a magnification of 50x or more is recommended to watch this event.

Nothing beats a telescope equipped with an H-alpha filter. H-alpha filters are narrowly tuned to the red glow of solar hydrogen. They reveal the sun as a boiling inferno cross-crossed by writhing magnetic filaments. On Nov. 11th, the tiny form of Mercury will join the fray.

Transits of Mercury occur only 13 times each century. The next one won't occur until Nov. 13, 2032. This is an unusual event, not to be missed, so stay tuned.

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