Star Party: Transit of Mercury Viewing at OMSI


A rare celestial event called a transit of Mercury is set to transpire on Monday, May 9,2016. The Oregon Museum of Science and Industry (OMSI) and the Rose City Astronomers Club will host a transit of Mercury viewing party in OMSI’s east parking lot for this occurrence, not to be repeated until the year 2019! 


A transit of Mercury is the observed passage of the planet Mercury across the disk of the sun.  It occurs when Mercury, orbiting the sun “on the inside track,” catches up to and passes the slower Earth.  To viewers, Mercury will appear as a small dot in the foreground, making its passage (or “transit”) from left to right across the southern hemisphere of the sun.


Transits of Mercury with respect to Earth are much more frequent than transits of Venus, with about 13 or 14 per century, in part because Mercury is closer to the Sun and orbits it more rapidly. 


For Portland, the transit will commence at 5:46 a.m. with the sunrise and Mercury appears near the Sun's equator.  The greatest transit movement will occur at 7:13 a.m. when Mercury appears just below the equator of the sun. The transit will end at 11:13 a.m. as Mercury exits to the lower west of the sun. Filtered solar telescopes will be available for safely viewing the sun during this transit. 


It is important not to view any of this transit activity without eye protection or without using indirect viewing techniques.  Viewers should use only an approved solar filter which blocks dangerous ultraviolet and infrared radiation as well as visible light.  Special solar viewing glasses are available at the OMSI Science Store.


Learn how to view the Mercury transit with the experts by joining us for the event at OMSI!