Solar Eclipses: Our Planet and Our Eyes

We know solar eclipses are very interesting and intriguing, but what are they, really?

On Monday, April 8th, the Moon aligned with the Earth and Sun at just the right distance to block out the Sun (1). Many people believe solar eclipses are a rare, once-in-a-lifetime occurrence, but it is only rare to see a total eclipse, such as April’s (2). There are a couple of types of solar eclipses. However, the more common solar eclipses are the annular eclipses, which happen every year or two. During an annular eclipse, the Moon comes between and aligns with the Earth and the Sun, but only while it is at its furthest point from Earth. But because the Sun is 400 times bigger than the Moon at this point, the Moon fails to significantly block the Sun’s light (1).

The picture above shows the science behind the eclipse and how it works when everything is in alignment.  

During a total solar eclipse, those in the path of totality could see the umbra, the darker inner shadow visible where the sun’s light is fully blocked. However, people outside the path of totality who could still see the partial eclipse were able to see the penumbra, or the lighter second shadow (2). On April 8th, the umbra arrived in Mexico, allowing people to see four minutes and twenty-eight seconds of the total eclipse, the longest time compared to every other area of totality (2). 

The eclipse on the 8th had many interesting effects on our planet and made many normally hidden celestial objects visible. For example, humans could view the sun’s corona, the outermost atmosphere of the Sun, which, at about 1.8 million degrees Fahrenheit, is much hotter than the sun’s surface. Additionally, Venus and Jupiter could be seen during the day in the areas of full totality (2). Because the Sun is our main source of heat and light, the temperature dropped even in areas with a partial eclipse, and people in the path of totality could see a sunset in all directions (2).

Above is an image of a total solar eclipse in the path of totality. 

As many know, looking at the Sun is extremely harmful during an eclipse, but most people do not know why or how this is. The Sun is more dangerous during an eclipse than in day-to-day life, but people are more responsible for Sun-inflicted eye damage than the Sun. During an eclipse, the darker sky causes our pupils to dilate (3). When light enters the eyes, the eye’s cornea focuses that light on the retina. allowing them to absorb more harmful light and ultraviolet Sun rays (4). Most people also stare directly at the Sun during an eclipse. Many burn their eyes without their knowledge, since the back of our eyes lack nerve endings, making it impossible to tell the extent of damage inflicted (3). The retina can handle day-to-day indirect light but is harmed when you stare directly at the Sun, which many people do during solar eclipses (4).

Solar eclipses, especially total solar eclipses, reveal the natural beauty within our universe. Witnessing one is an incredible and rare experience that shows that while the Earth, Sun, and Moon are beautiful individually, they are even more amazing together. 


  1. Types of Solar Eclipses – NASA Science. (2022, February 24). 
  2. Moench, M. (2024, April 6). 10 Surprising Facts About the 2024 Solar Eclipse. TIME; Time. 
  3. NBC Chicago Staff. (2024, April 8). Why is a solar eclipse dangerous to look at without proper eyewear? What to know. NBC Chicago; NBC Chicago.,only%20some%20locations%20will%20experience 
  4. Resnick, B. (2024, April 3). Eclipse 2024: How to protect your eyes during the total solar eclipse. Vox; Vox.