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How can the Moon, which is roughly 2,000 miles across, block the light of the Sun, which is about 865,000 miles across? It depends on how you look at it.

On Nov. 8, GLAS Education presented a 45-minute in-service for teachers from Rowe Elementary School, Chicago, demonstrating why we will see a solar eclipse on April 8, 2024. On that date, the Moon will cast an enormous shadow that will crawl over our Earth from Mexico, across the United States, and through Canada. In the center of the Moon shadow’s path, the Sun’s disc will be blotted out, creating what astronomers call “totality.” 

GLAS is cooperating with Northwestern Settlement House, Chicago, which owns and operates the K-8 Rowe charter school, to bring STEAM-oriented programs to Rowe students.

The eclipse demonstration was prepared by GLAS Education Director Kate Meredith and education staffers Adam McCulloch, Chris Kirby, GLAS board member Frances Dellutri and GLAS volunteer Ed Sadler, to show teachers why an eclipse happens and why “totality,” or the complete occlusion of the Sun’s disc by the Moon’s shadow, is visible only along a relatively narrow path on the Earth. The solar eclipse we see from Earth is a matter of perspective.The closer an object is to an observer, the larger it appears. The Moon is about 250,000 miles from Earth, while the Sun is 93 million miles away. As a result, the Moon, from Earth’s  perspective, appears to be the same size as the Sun.

GLAS Education showed Rowe teachers some ways they can integrate the April event into their classrooms and teach their students the importance of perspective in astronomical observation. GLAS plans to provide eclipse-based lessons for teachers at Rowe and also to campers at the House in the Wood camp, Delavan, which is also owned and operated by Settlement House. Those lessons will involve real-time activities if the skies are clear and visibility is good, and virtual learning activities if the weather does not cooperate.

Astronomers describe the apparent size of an object in the heavens by dividing the sky into degrees. Ed Sadler, a former physics teacher, showed Rowe teachers how to use fingers and hands to estimate the size of a section of sky. At arm’s length, a thumb will cover about a degree and a half. Three fingers will cover about 5 degrees. A clenched fist covers about 10 degrees. Index finger and little finger spread out spans about 15 degrees and the thumb and little finger spread out, like the Hawaiian hang loose sign, is 25 degrees.

Man on far right standing and holding up his index and little fingers, while people seated in auditorium chairs facing him are also holding up their hands and fingers.
Ed Sadler of GLAS Education shows how to estimate degrees of arc in the sky, used to measure the apparent size of celestial objects visible from Earth.

So how large does the Moon appear in the sky? Astronomers say that the Moon covers about a half degree of the sky. How large is that? Ed told the teachers to hold up their little fingers at arm’s length. The tip of the little finger, spanning about a half degree of the sky, is enough to cover the face of a full Moon. Sometimes a full Moon seems to expand as it crosses near the horizon, but that is an optical illusion, Ed said. The Moon’s face still covers just a half degree.

What about the Sun? Surprise. Despite its immense size, because of its greater distance from the Earth, the Sun’s disc also covers just a half degree of sky. However, because it is a glowing ball of nuclear fire, the little finger tip experiment is not recommended, unless one is wearing protective eyewear. 

Three people on a school stage, to the left a young man standing next to a bright, white photography light, next is a woman holding a tripod on wheels with a stick and small disc mounted on it, the third on the far right is a man leaning forward and lining his eye up with the disc and the light.
Rowe Elementary School teachers on right experiment with the demonstration model of an eclipse. Adam McCulloch of GLAS Education stands at left.

GLAS staff also provided the Rowe teachers a mock-up of totality, using a circular photography light and a small paper disc glued to a stick mounted to a tripod on wheels. With one eye closed, teachers were asked to look in the direction of the light and move the paper moon into a position where the disc of the circular light was just covered – Total Eclipse!  If the viewer’s eye were to shift position, totality is lost. The same thing happens to viewers on the Earth, GLAS staffers explained. Those in a position where the Moon’s shadow intersects directly with the Sun will see a total eclipse. Those whose positions on Earth are not in line with the Moon will see less of an eclipse or no eclipse at all.

Following the in-service, responses showed that 14 of the 20 teachers were interested in using the solar eclipse as part of their daily class activities. The initial goal was to get at least 10 teachers interested.

A post-presentation survey showed that GLAS got its point across. Some of the teacher comments were:

The teachers’ impressions of GLAS were also positive:

Former GLAS intern and University of Chicago astrophysics student Sydney Simon and GLAS board member Frances Dellutri continue to gather information about solar eclipse activities that provide cross-curriculum learning opportunities. Kate and Sydney are contacting the 14 Rowe Elementary teachers who are interested in solar STEAM activities to discuss their needs and interests.

GLAS’s next steps will involve individual meetings with the teachers. On Jan. 17, 2024, GLAS will lead another teacher in-service about solar eclipse activities.There will be separate professional development sessions for educators in the after school and early childhood education programs at Rowe. During February and March 2024, eclipse lesson plans will be finalized.

On April 8, 2024, teachers and students in leadership roles will roll out the solar eclipse event at Rowe Elementary School and House in the Wood Camp. All that will be needed are clear skies.

According to NASA, neither Chicago nor southeastern Wisconsin will experience totality during the eclipse, but the Moon is expected to cover about 95 percent of the Sun’s disc over Chicago, and about 90 percent over southeastern Wisconsin, including Milwaukee and Williams Bay. However, in southern Illinois, particularly in the Carbondale area, viewers will experience totality. Carbondale also experienced totality in 2017. On the whole, there are two to five solar eclipses each year, with a total eclipse taking place every 18 months or so. But folks in the Carbondale area are very lucky. According to Astronomy.com, on average, it takes about 375 years for a total solar eclipse to happen again at the same location.

The Illinois solar eclipse begins at 1:58 p.m. Central Daylight Time on April 8, 2024, with the final exit of the Moon’s shadow at 2:06 p.m. CDT. In Wisconsin, the eclipse begins at 12:50 p.m. Central Daylight Time and reaches maximum coverage at 2:05 p.m. The eclipse will end at 3:19 p.m. What’s more, in 2024 the Moon will be closer to the Earth than it was in 2017, so it will appear just a bit larger and it will take the Moon a bit longer to move in its orbit across the Sun’s disc.

After the April 8, 2024 eclipse, the next total solar eclipse to visit the contiguous United States will be about 20 years later, on Aug. 23, 2044. 

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