There will be a little black dot on the sun Monday.
It’s Mercury — the fastest and innermost planet of our solar system — flying across our luminous star for three hours on the morning of November 11.
A rare astronomical event known as the Mercury transit, it occurs about a dozen times a century. It happens in clusters; our last transit was only three years ago, in 2016. But the United States won’t see another one for 30 years, on May 7, 2049.
“For me, it makes the solar system real. Things are actually moving,” said William Phelps of the Peninsula Astronomical Society, which will be hosting a Monday viewing party at Foothill College Observatory in Los Altos Hills. Gatherings also will be held at in San Jose and Oakland.
“The clockwork of solar system goes on and on, with us and without us,” he said.
Barring fog, you can have breakfast with the view. California will see the transit as the sun rises, from about 6:45-10:05 a.m.
Mercury is small — only about 0.5 percent of the diameter of the sun — so a telescope magnifying at least 50 power will be needed to see it.
But a word of caution to prospective viewers: Never look directly at the sun with a telescope or binoculars. Just like viewing sunspots and partial solar eclipses, you need to use special solar filters to protect your eyes.
Named after the Roman deity Mercury, the messenger of the gods, Mercury normally looks like a bright star-like object. It’s usually seen near the western horizon after sunset or eastern horizon before sunrise, usually in twilight.
Its surface is heavily cratered and it has no atmosphere. Mercury’s temperatures are the most extreme of any other planet in the solar system, ranging from −280 °F at night to 800 °F during the day at its equatorial region.
Where to watch:
East Bay: Chabot Space and Science Center in Oakland, 7-10:30 a.m. https://chabotspace.org/events/events-listing/transit-of-mercury/
South Bay: Houge Park in San Jose, 8:30 a.m., https://www.meetup.com/SJ-Astronomy/events/265944456/
Peninsula: Foothill College Observatory, 6:45-10:05 a.m., http://www.pastro.org
Online at NASA’s Mercury Transit pag: https://mercurytransit.gsfc.nasa.gov/2019/
