Columbia, Md., May 11, 2016 - Transits of Mercury across the sun occur about 13 times a century. While not as rare as the transits of Venus, they occur infrequently enough that they are worth observing. For Jim Lochner, USRA Director, University Relations, this was a special event -- he saw his first transit of Mercury as boy in the early 1970's.
Andy Sakal, USRA Systems Administrator, views the transit of Mercury with Jim Lochner, USRA Director, University Relations who coordinated this special event.
This most recent transit was particularly noteworthy because of the month in which it occurred and because both the beginning and the end were visible in the United States. Transits of Mercury occur only in November and May, but more often in November. A May transit visible in its entirety, therefore, is quite rare.
At USRA's Columbia Headquarters Jim set up USRA's solar telescope, originally purchased for the transit of Venus , with an electronic H-alpha filter, with which solar prominences are visible.
Credit: NASA's Goddard Space Flight Center/Genna Duberstein, USRA Multimedia Producer
The telescope was set outside USRA's Columbia HQ for the beginning of the transit. Mercury moved onto the disk of the sun at about 7:13 AM near a prominence, which was a bonus. The magnification was not enough to detect the "drop effect" but Mercury's motion was clearly evident as it passed from first contact to second contact on onward. Unfortunately the clouds thickened, obscuring the view. The clouds thinned a bit a couple hours later, so we set up on the patio outside the café. About a half-a-dozen USRA employees came out to take a look at Mercury's black disk on the face of the Sun. Many were excited to see an event like this for the first time. However, the clouds thickened again and that was it for the day.
The next transit of Mercury is November 11, 2019. After that, the next transit of Mercury visible in the eastern United States will be May 7, 2049.
Universities Space Research Association is an independent, nonprofit research corporation where the combined efforts of in-house talent and university-based expertise merge to advance space science and technology. USRA works across disciplines including biomedicine, planetary science, astrophysics, and engineering and integrates those competencies into applications ranging from fundamental research to facility management and operations. USRA engages the creativity and authoritative expertise of the research community to develop and deliver sophisticated, forward-looking solutions to Federal agencies and other government sponsors.
Image: Composite image of Mercury transiting across the sun on May 9, 2016, as seen by HMI on NASA's Solar Dynamics Obersvatory. HMI is an instrument designed to study the magnetic field at the solar surface, or photosphere. Credit: NASA/SDO