Rare Transit of Mercury | Almanac.com

Rare Transit of Mercury

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Astronomers have been ranting and raving about the upcoming Transit of Mercury, on Monday, May 9. It is purportedly the year’s biggest sky event. Or, is it?

The transit is when the smallest, speediest planet partially eclipses the Sun.  And it’s kind of rare. The last happened ten years ago. The next two will occur in November 2019 and then November 2032.

But 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 this transit.

First the positives. It’s cool that a planet can partially eclipse the Sun. Mercury will glide across the face of the Sun as it rises on Monday morning, its small opqaue orb moving slowly across the massive solar disk. 

And unlike the last Mercury transit a decade ago, this one will be visible from the entire US and Canada.  The middle of the transit happens at 10:37 AM Eastern Time or 7:37 AM Pacific Time or 2:37 UTC.

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.

Your best bet is to phone your local astronomy club. Most are setting up the correct instruments for the public to use. As for spectacle, this is a bit esoteric. Mercury is only 12 arc seconds wide.  It will look like a dot that slowly changes position as the day wears on.

Mercury transits the Sun as seen from Earth in 2006. Credit: ESA/NASA/SOHO

Mercury transits have an interesting pattern.  They usually happen in November, but occasionally in May, and on no other month.  On average, there are 13 Mercury transits per century.  This one is favorable because Mercury will cross the Sun’s face not near its edge but almost centrally.  Also, this time around Mercury is about as close to Earth as it ever gets. So although it’s still tiny, it’s about as large as possible. 

A May Mercury transit is always followed in 3 1/2 years by a November one.  So if it’s cloudy on Monday and you really are itching to see Mercury cross the face of the Sun, you won’t have particularly long to wait.

Watch the Rare Transit of Mercury LIVE

Slooh will host a special live webcast of the rare Transit of Mercury live from its global network of observatories. Watch below or you go to Slooh.com to join and watch, snap and share your own photos during the event, chat with audience members and interact with the hosts, and personally control Slooh’s telescopes. 

Event Timings:

Live Stream starts: 4:00 AM PDT  ¦  7:00 AM EDT  ¦  11:00UTC

Live Stream ends: 11:45 AM PDT  ¦  2:45 PM EDT  ¦  18:45UTC

International Timings: http://bit.ly/23jg2To