A Stroke of Astronomical Luck for Solar Science

(6 June 2019)

Scientists plan for an eclipse over NSF’s observatory in Chile

On July 2, 2019 a total solar eclipse will pass over Chile and Argentina, and through a stroke of astronomical luck, the path of totality crosses directly over the National Science Foundation’s (NSF) Cerro Tololo Inter-American Observatory located in the foothills of the Andes, 7,241 feet (2200 meters) above sea level in the Coquimbo Region of northern Chile. Five science teams chosen by NSF’s National Solar Observatory will perform experiments at Cerro Tololo during the eclipse; four of them will have their equipment trained on the Sun’s elusive corona and one will study eclipse effects on the Earth itself.

The Sun’s Corona

Throughout history, total solar eclipses have amazed humankind. Many cultures’ eclipse myths and legends portray them as divine, fortuitous or even ominous events. Today we understand the science behind why total solar eclipses occur. But we can still learn a lot about the Sun during the brief minutes of totality, when the Sun is completely blocked by the Moon. For scientists, a total solar eclipse offers a rare opportunity to study a part of the Sun they don’t normally see, its inner corona.

The corona is a region of magnetism and extraordinarily hot gasses that makes up the outermost part of the Sun’s atmosphere. It has mysterious properties we have yet to understand, like why it is extremely hot, hotter than the surface of the Sun. It is especially difficult to study because it is less dense and millions of times dimmer than the visible disk of the Sun and thus hard to see in the sun’s full glare. However, when the bright disk of the Sun is completely covered by the Moon, as in a total solar eclipse, we can see its corona shining.

Scientists study the corona because it is important for predicting space weather, a phenomena that can potentially damage our electrical grids, telecommunications and satellites. Space weather occurs when the Sun occasionally spews magnetic plumes called coronal mass ejections into space. If one of those plumes is aimed at Earth, we could experience electrical and telecommunication disruptions like the super solar storm of 1859 known as the Carrington event, that burned up telegraph wires around the world. Such magnetic storms carry a much greater risk today in our electronically connected and dependent world.

Each of the following five science teams are taking advantage of the 2 minutes and 6 seconds of totality on Cerro Tololo to increase our understanding of the Sun’s mysteries and its impact on Earth.



The Cerro Tololo Inter-American Observatory (CTIO) is a complex of astronomical telescopes and instruments located at 30.169 S, 70.804 W, approximately 80 km to the East of La Serena, Chile, at an altitude of 2200 meters.  CTIO headquarters are located in La Serena, Chile, about 300 miles north of Santiago.

The CTIO complex is part of the U.S. National Optical Astronomy Observatory (NOAO), along with the Kitt Peak National Observatory (KPNO) in Tucson, Arizona.  NOAO is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation (NSF).  CTIO, as part of the AURA Observatory in Chile, operates in Chile under Chilean law, through an Agreement with the University of Chile and with the auspices of the Ministry of Foreign Affairs of Chile.

The principal telescopes on site are the 4-m Victor M. Blanco Telescope and the 4.1-m Southern Astrophysical Research (SOAR) telescope.  One of the two 8-m telescopes comprising the Gemini Observatory is co-located with CTIO on AURA property in Chile, together with more than 10 other telescopes and astronomical projects.