May 9, 2016 Transit of Mercury

Date: May 9, 2016
Time: transit from 11:12:19 to 18:42:26 (times are given in UT)
Place: if you can see the Sun you can see this transit

On May 9th (next Monday) the planet Mercury will pass between Earth and the Sun in an event known as a transit. It will appear as a tiny, slow-moving, black dot silhouetted on the face of the Sun. The photo above is from a sequence of images I shot for a time-lapse video of the last Mercury transit. You can see that video here (scroll down to the bottom).

For those interested in photography, here’s the specs from my shoot:

Optics: Takahashi FS-128 + Coronado SM40 H-alpha filter + 10 mm TeleVue Plossl (eyepiece projection)
Imaging: Canon EOS 20D, EFL 4000 mm, f31, ISO 3200, 1/200 sec
Location: Heimhenge, New River, AZ
Date: Nov 8, 2006

WARNING: You cannot safely view this event without following specific precautions. Your eyesight can be permanently damaged if you ignore this warning. There’s a summary of safe viewing procedures for both transits and eclipses here.

Mercury’s path across the face of the Sun will be about as long as it ever gets, lasting for 7 hours 30 minutes. Click on the thumbnail below to see a diagram produced by Fred Espenak at

Whether you’ll be able to see it or not depends where you are on the planet. Alas, here in Arizona the transit will already be in progress when the Sun rises at 5:38 am (MST), and it won’t be until around 7:00 am that the Sun has enough elevation for clear viewing. Click on the thumbnail below to see Espenak’s diagram of transit visibility around the globe.

Transits of Mercury are not really that rare. They occur 13-14 times each century, in May or November, when Mercury’s orbit (inclined at 7°) is favorably positioned as seen from Earth. The next transit will occur on November 11, 2019. The last one was on November 8, 2006 (when I shot the photo above).

Next Week in Sky Lights ⇒ Synchronous Lunar Rotation

An Illusion Caused by Perspective
Q&A: Synchronous Lunar Rotation