Moon vs. Sun: solar eclipse of the century

North America viewed the total solar eclipse yesterday. Students  on campus viewed the eclipse on a solar projection telescope near Pursley Hall. Annie Goodman/The Lion’s Roar

The first solar eclipse visible in totality to pass across the United States since June 1918 was visible as a partial eclipse in Louisiana.

The eclipse crossed the United States on Monday, Aug. 21 between 9:05 a.m. PT in Oregon and 4:10 p.m. ET in South Carolina. Locally, the eclipse was visible between noon and 3 p.m. with the peak of visibility occurring around 1:30 p.m.

“A solar eclipse happens when the moon passes between the Earth and the sun,” said Head of the Department of Chemistry and Physics Gerard Blanchard. “This happens when a new moon occurs at the same time as the sun is near the line where the Earth’s orbital plane and the moon’s orbital plane intersect. Otherwise, the new moon passes over or under the sun from Earth’s point of view. This give us two ‘eclipse seasons’ each year, and one or two solar eclipses occur somewhere on the Earth each season.”




An eclipse is classified based on how much of the sun is covered at the peak of the eclipse. Though this is classified as a total solar eclipse, it will not be visible in totality from Louisiana.

“The eclipse seasons occur slightly earlier each year so that the dates of eclipses tend to get slightly earlier each year,” said Blanchard. “Even though solar eclipses happen fairly frequently, one geographical location on Earth sees them rarely because the size of the moon’s shadow on the Earth is fairly small and the eclipse happens fairly quickly.”

Just as it is not safe to stare at the sun on a regular day, Blanchard explains that looking directly at a solar eclipse can be harmful.

“Watch safely,” said Blanchard. “Get certified glasses from a reputable supplier, or use a projection method such as a pinhole camera, easy and quick to make, or a solar projection telescope. Weather permitting, I will be on the lawn between Pursley Hall, Mims Hall and Tinsley Hall with a solar telescope for viewing on Monday between 1 p.m. and 2 p.m.”

According to Blanchard, it will be six and seven years before Hammond will see another solar eclipse.

“The next solar eclipses visible from Hammond will be on Oct. 14, 2023, 44th eclipse of Saros Cycle 134, and April 8, 2024, 30th eclipse of Saros Cycle 139,” said Blanchard.

Blanchard explains how this solar eclipse is different.

“What’s special about this eclipse is that it is the 22nd eclipse in Saros Cycle 145,” said Blanchard. “That is a series of 77 eclipses that recur every 18 years, 11 days and eight hours.  The cycle started in 1639 with a partial eclipse near the north pole and will end in 3009 with a partial eclipse near the south pole.  In between those, the location of every successive eclipse moves southward and westward in spiral around the Earth.”