To acquire wisdom, one must observe

Brandeis professor Seth Fraden delivers seminar on solar eclipses

Brandeis Professor of Physics Seth Fraden recently delivered a talk at the Rapaporte Treasure Hall titled “En busca del camino de la totalidad,” or “In search of the path of totality.” During his lecture, Fraden discussed both the astronomical phenomena that occur during solar eclipses as well as his own experiences witnessing solar eclipses. He also shared several tips for enjoying the upcoming solar eclipse on April 8.

Solar eclipses occur when the position of the moon is in between the Earth and the sun such that the shadow of the moon is cast upon the Earth. Although the moon passes in between the Earth and the sun during the new moon phase in a cyclical manner, the correct orientation for the moon’s shadow to fall on the Earth is a rare celestial event. This is because the moon’s orbit around the Earth is in a different plane than the orbit of the Earth around the sun; the moon’s orbit is slightly tilted. As a result, the moon typically orbits either above or below the region required to obstruct the sun’s light, causing the sunlight to reach the Earth without occlusion. 

Solar eclipses occur when the moon is precisely oriented directly in between the sun and the Earth such that the moon’s shadow reaches the Earth. This unique alignment results in two distinct parts of the moon’s shadow, known as the umbra and the penumbra. The umbra is where the sunlight is completely occluded, and the penumbra is where part of the sun is occluded. Viewers in the umbra experience a total solar eclipse, while viewers in the penumbra experience a partial solar eclipse. 

Detailed accounts of solar eclipses are not common in human history. The oldest recorded evidence of a solar eclipse within the span of human history may have occurred on Nov. 30, 3340 B.C.E., where archaeologists found petroglyphs, or rock carvings, in modern day Ireland depicting overlapping concentric circles. Later on in 1200 B.C.E., scribes from ancient China recorded the occurrence of solar eclipses through oxen shoulder blades and tortoise shells, where the observation, “The Sun has been eaten” was ingrained.

Fraden shared his first solar eclipse experience during his time as an undergraduate at the University of Berkeley in Berkeley, California, where he majored in physics. Thrilled by the prospect of catching a total solar eclipse, Fraden and his friends from the astrophysics department drove to Oregon and frantically climbed a hill to avoid the overcast weather. His friend had made a timelapse camera in anticipation. He described what the eclipse looked like, saying, “It’s like a shadow cast from the clouds … [that] extends from the Northern Hemisphere to the Southern, from the ground to the heavens … and the shadow is hurtling towards you at three times the speed of sound … it’s just getting darker and darker, this wall of darkness … You look up at the sun and now you see the corona and the stars.” Humorously, Fraden recounted, “Of course my buddy forgot to turn on his camera. He only discovered it after this thing had passed. But it didn’t matter; the vivid memory, even after 45 years, remains on our minds.”

This year, the solar eclipse will begin in the U.S. at around 12:30 p.m. central time, at which point it will be in the southwest region of Texas. The complete path of totality is about 115 miles wide, however viewers pretty much across the country can see at least a partial solar eclipse.

Fraden shared his plans to go to the city of Mazatlán in Mexico in order to catch this year’s solar eclipse. Mexico’s pacific coast will be the first location in North America to encounter the 2024 solar eclipse. Due to its ideal location and the anticipated clear skies, Mazatlán is an optimal viewing location. Fraden recommended that in addition to seeing the corona of the sun, make sure to keep an eye out for the changing landscape around you. For example, during a solar eclipse, the outer atmosphere can be visualized due to the sparsity of light.

According to Fraden, one great place to view the eclipse in New England is the Jay Peak mountain in Vermont. In New Hampshire, the southernmost edge of the path of totality will be just north of the White Mountains. Further north in Maine, Mount Katahdin is another ideal location for viewing the solar eclipse in the path of totality.

The Brandeis community will be able to observe the Moon occluding the Sun starting from 2:30 p.m. in Waltham. This will eventually culminate in a 93% occlusion by the time 3:29 p.m. The Brandeis Physics Department and the Brandeis Library have provided protective eyewear for viewing the solar eclipse. Students are encouraged to join together in Fellows Garden for the viewing on April 8.

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