Solar Eclipse Resources
eclipse (noun) :
passing into the shadow of a celestial body
Solar eclipses are deeply rooted in Yerkes’ history.
During the 20th century, Yerkes astronomers traveled the world to observe solar eclipses first-hand. The first solar eclipse expedition on May 28, 1900 was led by the observatory’s founder George Ellery Hale, where he and a group of astronomers traveled to North Carolina to observe a total solar eclipse. In total, Yerkes astronomers went on at least ten total solar eclipse expeditions between 1900 and 1952, providing invaluable data to test fundamental physics, including Einstein’s Theory of General Relativity, and deep insights into the atmosphere of our nearest star – the Sun.
Like the great astronomers at Yerkes, you will have two chances through April 2024 to take your own eclipse expeditions in the United States.
October 14, 2023
Annular Solar Eclipse
Join us at Yerkes for a special Community Day, where we’ll welcome members from the community to observe this spectacular eclipse event at the observatory. When viewed from Williams Bay, WI, this will be a partial solar eclipse, with 40-50% of the Sun’s light blocked by the Moon. The annular solar eclipse will be visible in the western and southwestern United States, Mexico, Central America, and South America.
Our community day event requires tickets, which will be made available through our events page. We will have several ways of safely viewing the eclipse during the event, as well as hands-on activities, food options, and other vendors from Williams Bay.RESERVE
April 8, 2024
Total Solar Eclipse
The path of totality is relatively close but does not pass through Williams Bay, WI on April 8, 2024. Because experiencing a total solar eclipse is unlike any other astronomical event, we at Yerkes encourage everyone who is able to travel to a location in the path of totality. We recommend using this Interactive Google map of the United States to identify your destination for the total solar eclipse.
Yerkes staff will be taking their own eclipse expeditions to experience totality, so the Observatory will not be hosting a viewing event on April 8, 2024. Instead, we encourage those who are unable to travel to the path of totality to contact their local libraries or astronomy clubs for a local viewing event. If you decide to stay local, please note that this will be a partial eclipse as viewed from Williams Bay, WI.
Frequently Asked Questions
What is an eclipse?
An eclipse occurs when some or all of the light from one celestial object is blocked by another celestial object passing between it and an observer. In the case of a solar eclipse, the Moon passes between the Sun and Earth, blocking the light from the Sun as seen by an observer on Earth.
Credit: NASA’s Goddard Space Flight Center
One amazing coincidence of our solar system is that the Moon and Sun, as seen from Earth, are approximately the same angular size. This means that they take up the same amount of space in Earth’s sky, allowing the Moon to perfectly block out light from the Sun when the two are aligned.
How can I safely view a solar eclipse?
First things first – it is not safe to look directly at the Sun without special equipment. You may have heard there is a caveat to this during a solar eclipse – while it’s true that you can look directly at a total solar eclipse during the few minutes that the Moon is completely blocking the light from the Sun (totality), you generally should not look at the Sun with just your eyes during a solar eclipse.
For the October 14, 2023 annular eclipse
Even during totality, a small portion of the Sun’s surface will still be visible during this eclipse. You will need to use protective measures at all times when observing this eclipse.
For the April 8, 2024 total eclipse
With the exception of the few minutes of totality, you should always use protective measures while observing this eclipse.
Here are some options for safely observing the Sun during an eclipse:
These special glasses use solar filters that block out more than 99% of the Sun’s light, making it safe to look directly at the Sun while wearing them. It is crucial that you buy these from a trustworthy source, as using counterfeit or damaged glasses could cause permanent eye damage. The American Astronomical Society has compiled an extensive list of approved suppliers of eclipse glasses for your reference.
Projecting the Sun’s light using a pinhole observer is another safe and easy way to view a solar eclipse. Check out these instructions for how to build your own pinhole observer with common household items.
Specialty filters and telescopes
Though this option is a bit more expensive, you can purchase your own specialty filters to safely view the Sun with a telescope or binoculars. All of the filters block out at least 99% of the Sun’s light, making it safe to look directly at the Sun using your instruments. Some filters only let a certain wavelength, or color, of light through, allowing a unique view of different components of the Sun. The American Astronomical Society has also compiled an extensive list of recommended filters and telescopes for your reference.
What are the different types of solar eclipses?
A partial solar eclipse occurs when only some of the Sun’s light is blocked by the Moon. This happens when the Sun and Moon are not perfectly aligned when viewed from Earth.
An annular solar eclipse occurs when the Moon and Sun are aligned as seen from Earth, but the Moon is at the farthest point from Earth in its orbit. Because the Moon appears smaller when at its farthest point from Earth, the Sun is not completely covered during an annular eclipse. This creates the characteristic ring around the Sun that is observable during an annular eclipse.
A total solar eclipse occurs when the Moon and Sun are aligned as seen from Earth, with the Moon completely blocking the light coming from the Sun’s surface. Because Earth’s surface is curved, some solar eclipses can shift between annular and total depending on the observer’s location. An eclipse that shifts between annular and total is known as a hybrid solar eclipse.
How rare are solar eclipses?
It’s a common misconception that solar eclipses are rare. Partial solar eclipses happen at least two times a year, and the most sought-after eclipse, a total solar eclipse, happens approximately once every 18 months. Although solar eclipses happen quite frequently, the location an eclipse is visible changes from eclipse to eclipse. This is what gives solar eclipses a sense of rarity; observers often have to travel great distances to be able to experience an eclipse.
Keep Yerkes open for a new generation of explorers
Help us continue
More than a century ago a determined founder, masterful architect, skilled trades workers, diligent engineers and inventive entrepreneurs built Yerkes. Visionary scientists put it on the galaxy’s map. A dedicated group of locals saved Yerkes for future generations. And now we look to you. Please consider becoming a contributor and friend of Yerkes Observatory. Your participation means everything.
Want to talk about an estate or legacy gift? Want to see if you can help us with your time as a volunteer?