Nature’s Beauty on Stage

Eclipses fascinate and inspire us. On Monday our daily routines will be interrupted by the passage of the moon directly in front of the sun that we call a solar eclipse. We will have no choice but to want to look up to take in the splendor of this relatively rare event in nature that will happen regardless of the work deadlines which time your next class starts on campus.

A word of caution: please do NOT look at the eclipse directly. One will need ‘eclipse’ glasses to protect from harmful high frequency light from the sun’s outer layers that can destroy our retinas.

Eclipses make for splendid excuses for doing science experiments. The stories are too many to recount here, so let's narrow the discussion to famous experiments in the area of chemistry alone.

For example, 1868 scientist Pierre Janssen viewed an eclipse through a prism. The prism broke up the light into a rainbow of colors called a spectrum which revealed bright emission bands of light which he correcting associated with being produced by the chemical element of hydrogen.

Curiously, he also saw a bright emission band that was yellow in color. This yellow feature turned out to be produced by the element helium, and this experiment marked the identification of the second element of the periodic table. In sum, we discovered helium in the sun before we found it on Earth!

A year later, in 1869, scientists Charles Augustus Young and William Harkness did a similar experiment and this time in addition to hydrogen and helium they found a closely-spaced pair of green emission bands. It was hypothesized that this might be the discovery of yet another new element in the periodic table.

As the only light they we see during an eclipse is from the outer layers of the sun, the chromosphere and the corona, it was decided to name this potential new element “coronium.” This time it would take another 60 years to correctly identify these green emission bands. As it turned out, they were traced not to a new element but to the known element of iron (Fe).

Iron itself was not all unusual in the 1800’s, so why were scientists so slow to identify it? It turns out that the outer layers of the Sun are so hot that they had removed half of the electrons from the iron atoms, thereby giving it spectral characteristics that we were unused to experiencing here on Earth.

Enjoy the eclipse on Monday!

Dr. Brenda Frye

About Dr. Brenda Frye

Brenda L. Frye is an observational cosmologist at the Department of Astronomy/Steward Observatory, University of Arizona. She earned her Ph. D. in Astrophysics from the University of California at Berkeley, assisted by a National Science Foundation Graduate Research Fellowship.

Her thesis work involved measuring the concentration of the total mass of visible plus dark matter in the fields of massive galaxy clusters, a program requiring the use of some of the largest telescopes in the world.

Moving a mile from her Ph. D. institution, she assumed a postdoctoral position with the Supernova Cosmology Project at Lawrence Berkeley National Laboratory under the direction of Professor Saul Permutter.

She then treked across the country to take a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship and a Princeton Council on Sciences and Technology Fellowship both at Princeton University.

Moving further east, she became a Lecturer in Physics at Dublin City University in Dublin, Ireland, where a number of European collaborations were formed.

From there she crossed back across the pond to the west coast of the U. S. to become a tenure-track Assistant Professor of Physics at the University of San Francisco.

Her travels have now landed her at her Alma Mater in Tucson, where she teaches and does research. The aims of her research continue to be to use gravitational telescopes in space as 'lenses' to study the properties of dark matter and those of distant galaxies back to when the universe was <900 million years old.

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