How the 2019 eclipse will differ from 2017’s — and what that means for science

Chasing the moon’s shadow is never easy

composite image of 2017 total solar eclipse

INTO THE DARK AGAIN  This composite image shows the eclipsed sun on August 21, 2017, the last total solar eclipse. The faint disk of the moon is visible in the center, and the pale wisps of the solar corona surround it. On July 2, scientists will observe another eclipse over parts of South America.

Solar Wind Sherpas project, P. Horálek, ESO

Two years ago, scientists towed telescopes and other equipment into fields and up mountains across the United States for a celestial spectacle: the 2017 Great American Eclipse.