One of the brightest astronomical events of the year is less than a week away. The transit of Mercury will take place on Monday, November 11. The distant planet will be slowly sliding across the solar disk in the form of a small dark point. The transit will begin at 3:35 p.m. Moscow time and will last six hours.
Residents of all continents, except Australia, will see at least part of the phenomenon. Only the beginning of the process will be visible in the northern latitudes because of the early sunset.
From Earth, the planet is only 1/194th of the Sun’s apparent diameter. To observe the transit, a safely-filtered telescope with a magnification of 50x or more is recommended. If there is no filter, the image can be projected onto a wall or screen through a telescope. Do not look at the Sun without protection, as eye damage can occur.
Telescopes equipped with an H-alpha filter are the most interesting ones. They are tuned to the red glow of solar hydrogen and show the Sun as a boiling inferno crossed by dark magnetic filaments. On November 11, tiny Mercury will move across this starscape. Here’s an example of an H-alpha image taken during the last transit of Mercury on May 9, 2016.
© Paul Andrew
Paul Andrew took this image using his observatory in Dover, the UK. The background prominence made Mercury look like a comet with a tail.
Transits of Mercury occur only 13 times a century. The next one is expected on November 13, 2032.