Monday’s transit of Mercury: The year’s biggest sky event?

(NASA’s Goddard Space Flight Center/SDO/Genna Duberstein)

If you know any backyard astronomers, you’ve heard them rant and rave about the upcoming transit of Mercury on November 11. It is purportedly the biggest celestial event of the year. It’s when the smallest, speediest planet partially eclipses the Sun. And it’s kind of rare. The next won’t occur until November 2032.

Honestly, I’m not at all sure this will pan out for the vast majority of people. So let’s look at the positives and negatives of Monday’s transit.

First, the positives: It’s cool that a planet can partially eclipse the Sun. And the whole concept is understandable. In our modern era of esoteric celestial happenings, we hear words like “exoplanets” and “dark energy,” yet here we have an event whose only terms are planet and Sun.  A planet passes in front of the Sun: easy. Who doesn’t like easy?


Moreover, this will be visible from our neck of the woods. It lasts over seven hours, with the middle of the transit happening at around 10:30 a.m., when the Sun isn’t too low.

Negatives: you can’t look at the Sun – at least, not if you value your eyesight. So you need eye protection. But even that is not enough. Unlike the transits of Venus in 2004 and 2012, a Mercury transit cannot be seen without a telescope. And it can’t be an ordinary telescope; it has to be equipped with a safe solar filter. Do you own such a thing? I didn’t think so.

Unless you have a friend who has one, and he’s off on Veterans’ Day on Monday, your best bet is to phone your local astronomy club. Around here, the Mid-Hudson Astronomy Association will set up the correct instruments.

As for spectacle, this is a bit esoteric. Mercury is only half the size of Venus, but twice as distant. So it will look like a dot in the center of the Sun at 10:30 a.m. Then it will slowly change position during the transit, continuing until late afternoon.

Mercury transits have an interesting pattern. They usually happen in November, but occasionally in May, and in no other month. On average, there are 13 Mercury transits per century. This one is a bit unusual because Mercury will cross the Sun’s face not near its edge, but centrally.

A good option is to go on, where I’ll be narrating some of it, and where we will have ideal equipment set up.

Happy Transit!

Want to know more? To read Bob’s previous columns, click here. Check out Bob’s podcast, Astounding Universe, co-hosted by Pulse of the Planet’s Jim Metzner.