Watching the Sun: Eight Solar Observatories From 1899 to 2019

Founded in the Palani Hills of Tamil Nadu in 1899, with first observations in 1901, Kodaikanal is the starting point. Its photographic record of the Sun now spans more than a century, which makes its sunspot archive a key resource for studying long-term solar cycles.

Built in 1969 on a peninsula in Big Bear Lake, California, this observatory uses the surrounding water to suppress the turbulent air that blurs ground-based views of the Sun. The idea of a lake site, not a mountaintop, shaped the next stop.

Established in 1976 on an island in Fateh Sagar Lake and modeled on Big Bear, Udaipur carries the lake-site idea to India. It also fills a geographic gap in the worldwide Global Oscillations Network Group between Australia and Spain.

Set up jointly by Australia and the United States in 1977 and operational from 1979, Learmonth near Exmouth was chosen for clear skies and low radio interference. It watches for solar flares that can disrupt satellites and long-range communication.

Founded in 1984 and headquartered in Boulder, Colorado, the National Solar Observatory brings several solar sites under one federally funded center, including Sunspot in New Mexico and six stations of the Global Oscillation Network Group.

Launched on 2 December 1995, this joint European and NASA spacecraft sits at the Sun-Earth Lagrange point L1 and has an uninterrupted view of the Sun. It studies everything from the solar interior to the solar wind, and it is the first space-based stop on the path.

Launched on 11 February 2010 as part of NASA's Living With a Star program, it observes the solar atmosphere continuously in many wavelengths from an inclined geosynchronous orbit, producing roughly 1.5 terabytes of data per day.

Completed in 2019 on Haleakala in Maui, its 4-meter mirror makes it the largest solar telescope in the world, and its first images in December 2019 resolved features about 30 kilometers across, the finest detail seen on the Sun from the ground.