See the Sharpest-Ever View of Mercury's Transit Across the Sun

On May 9, the solar system's innermost planet migrated across the bright disk of the sun. Amateur astronomers and professional observatories alike captured images and videos of this rare event. 

But one view of Mercury's pilgrimage accomplished something unprecedented: the highest-ever spatial-resolution images of a Mercury transit. The images are featured in this awesome video, which begins with footage taken by NASA's Solar Dynamics Observatory (SDO). It then fades into the high-res images, which show the tiny, black disk of Mercury against the bright solar background.

The high-res images were taken by the New Solar Telescope (NST) at the Big Bear Solar Observatory outside Los Angeles. The 1.6-meter-diameter (5.25 feet) NST is "the highest-resolution solar telescope in the world, so its images are the sharpest," Bin Chen, an assistant professor of physics at the New Jersey Institute of Technology, told in an email.

"About midway through the transit, the sun became visible at NST's location in California," Chen said. "The clarity of the images was aided by the ability of the NST's adaptive optics system to lock onto the dark disk of Mercury, thus improving the corrections for turbulence in the Earth's atmosphere." 

The space-based SDO views the sun in a wide range of wavelengths, so it captured the Mercury transit in a whole rainbow of "colors." The human eye can't see most of the wavelengths collected by SDO, but images and videos from the observatory translate those different wavelengths into colors that humans can see. The video above (compiled by Chen) first shows the sun in extreme ultraviolet light, captured by SDO. NST captures optical light, and has "more than 10 times better spatial resolution" than SDO, according to Chen.

To see the transit of Mercury through SDO's eyes and in many different wavelengths, check out the video below.

The Big Bear Solar Observatory and the NST are part of the New Jersey Institute of Technology Center for Solar-Terrestrial Research (NJIT-CSTR). The observations of Mercury's transit were taken by Dale Gary, NJIT's director of solar observatories, with assistance from Kevin Reardon, and a scientist at the National Solar Observatory, and Jay Pasachoff, a scientist at Williams College.

Transits of Mercury occur about 13 times per century. The next transit will occur in 2019.  

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Calla Cofield
Senior Writer

Calla Cofield joined's crew in October 2014. She enjoys writing about black holes, exploding stars, ripples in space-time, science in comic books, and all the mysteries of the cosmos. Prior to joining Calla worked as a freelance writer, with her work appearing in APS News, Symmetry magazine, Scientific American, Nature News, Physics World, and others. From 2010 to 2014 she was a producer for The Physics Central Podcast. Previously, Calla worked at the American Museum of Natural History in New York City (hands down the best office building ever) and SLAC National Accelerator Laboratory in California. Calla studied physics at the University of Massachusetts, Amherst and is originally from Sandy, Utah. In 2018, Calla left to join NASA's Jet Propulsion Laboratory media team where she oversees astronomy, physics, exoplanets and the Cold Atom Lab mission. She has been underground at three of the largest particle accelerators in the world and would really like to know what the heck dark matter is. Contact Calla via: E-Mail – Twitter