GLOBE's Eyes on the July, 2019 South American Eclipse

Did you know that nearly everything on Earth—you, your computer, all the plants and animals, even the weather—gets its energy from the Sun? The Earth is a solar-powered planet; light from the Sun travels towards Earth where it is absorbed by the surface and reemitted in the form of heat radiation. This energy exchange is what keeps the planet warm and lets it support life.

So, what do you think would happen if you could dim or block out the Sun like you can a desk lamp? For those of you at the right time and place later this summer, nature is providing an exciting opportunity to do just that!

On July 2, 2019 a total solar eclipse will pass across the southern part of South America. The eclipse will begin over the Pacific Ocean, and the lunar shadow will enter South America near La Serena, Chile and end near Chascomús, Buenos Aires, Argentina. Outside this path, a partial solar eclipse will be visible in the rest of Chile and Argentina as well as Ecuador, Peru, Bolivia, Paraguay, Uruguay and parts of Colombia, Brazil, Venezuela and Panama. These celestial events have inspired wonder and awe throughout human history.

Diagram of the eclipse path for 2 July 2019
Image Credit: NASA's Scientific Visualization Studio
Figure 1. This map shows the global view of the path of totality as well as the partial eclipse zones for the solar eclipse on July 2, 2019. More information: https://svs.gsfc.nasa.gov/4713

 

A solar eclipse happens when the Moon passes between the Earth and the Sun, blocking some or all of the Sun’s light from parts of the Earth’s surface. During an annular or partial eclipse, the Moon only blocks some of the Sun. A total eclipse occurs when the disk of the Sun is completely obscured, briefly allowing us to view the solar corona with the naked eye.

 
Image Credit: NASA 2017 Total Solar Eclipse event page, updated by GLOBE Observer team for 2019
Figure 2. Diagram showing the Earth-sun-moon geometry of a total solar eclipse. Not to scale: If drawn to scale, the Moon would be 30 Earth diameters away. The sun would be 400 times that distance.

 

A total eclipse provides a unique opportunity for scientists to study the effects of the Sun’s radiation on the Earth’s surface. Cut off from the Sun’s light, air and surface temperatures drop rapidly, with some observers noting drops of up to 3° Celsius in air temperature during a partial eclipse over the United Kingdom in spring 2015. (Check out the National Eclipse Weather Experiment at the University of Reading for more on that study, or see a paper on the citizen science efforts here.) Wind speed and direction may change; as early as 1715 Edmund Halley (of Halley’s Comet) noted a “chill and damp that attended the darkness” during an eclipse, and subsequent studies have examined the causes of those changes. Animals within the path of totality react as well, with night creatures awakening while daytime wildlife goes quiet.

If you’ve ever wanted to do an experiment where you could dim or turn off the Sun the way you can a desk lamp, nature is providing a rare opportunity on July 2, 2019. What solar powered protocols will you be watching?


SAFETY NOTE: The ONLY time it is safe to look directly at the Sun without eye protection is during the brief window of complete totality when the Sun’s disk is completely obscured by the Moon. At all other times, please be sure to view the eclipse through safe lenses, either through filters on a telescope or by using eclipse glasses. The safest way to observe the eclipse is by using indirect methods. For more information, please visit this NASA eclipse safety page.