On August 21, 2017, there will be a total solar eclipse visible across the contiguous United States. For about 3 minutes, the Moon will entirely block the light of the Sun. Dusk will fall in the middle of the afternoon. Stars will be visible. This rare sight is one of the most wondrous in all of nature. The Dome Planetarium is your resource for information about this fantastic sight!
The Moon blocks out the light of the Sun in a total solar eclipse, leaving just prominences and the Sun's atmosphere visible. Image source: Phil Hart
What is a total solar eclipse?
A solar eclipse occurs when the Moon covers up the Sun from our perspective here on Earth. The Sun is 400 times larger than the Moon, but by coincidence is also 400 times farther away, so the two objects appear to be the same size in our sky. This is the reason solar eclipses can occur. Every once in a while, the Moon passes directly between the Sun and the Earth, and blocks out the sunlight for a short amount of time.
When the Moon passes directly between the Sun and Earth, people in the dark part of the shadow will see a total solar eclipse. Objects are not to scale. Image Credit: Wikipedia Commons.
If the Moon orbited the Earth in exactly the same plane that the Earth orbits the Sun, we would have a lunar eclipse and a solar eclipse every month (sort of like on Mars). The reason this does not happen is because the Moon's orbit is slightly tilted in relation to Earth's orbit. Usually the Moon passes just over, or just under, the Sun's path in our sky.
Image Credit: SMU Physics
Total solar eclipses are more rare than lunar eclipses because the Moon's shadow on the Earth is much smaller than the Earth's shadow cast out into space (the cause of lunar eclipses). There is only a thin path on the Earth where a total solar eclipse is visible.
How can you watch the August 21, 2017 eclipse?
The total solar eclipse is only visible in a narrow path along the United States. In Peoria, the Sun will only by 90% eclipsed. If you want to see the total eclipse, you will need to travel to the path of totality. The closest cities along the path of totality to Peoria are in Southern Illinois (about a 5 hour drive) or near St. Louis (about a 3 hour drive).
The Shawnee National Forest and Carbondale will be good places to watch the eclipse. Image Source: GreatAmericanEclipse.com
Carbondale gets 2 minutes and 35 seconds of totality. Southern Illinois University is having a big event for the eclipse. Check out their website for information. Marion has 2 minutes and 28 seconds.
From the Peoria area, it will be a little bit of a shorter drive to totality in Missouri.
You will have to go a bit south or east of St. Louis to get the longest duration of the eclipse.
In Missouri, good cities to observe are Festus (2 minutes and 37 seconds) and St. Genevieve (2 minutes and 40 seconds) near the centerline of the eclipse.
The large yellow band across the country is the path of totality. Everywhere else in the United States a partial solar eclipse will be visible.
You might want to plan a vacation around the eclipse, and travel to a beautiful destination to watch. If that is the case, check out this excellent interactive Google Map showing the eclipse path across the United States. You can also order a Road Atlas of the eclipse.
How to safely watch a solar eclipse
For most of the eclipse when the Moon is not fully covering the Sun, you need to wear proper eye protection to be able to see anything, and to stay safe. Eclipse glasses are a popular choice, and are very inexpensive. The Peoria Riverfront Museum's store has them for sale for $1.50.
In Southern Illinois, the partial phase will start at 11:52:26 AM (CDT). You will see a small shadow appear on the upper right side of the Sun as the Moon begins to cover it. The Sun will be totally eclipsed from about 1:20 PM to 1:23 PM. The eclipse will end at 2:47 PM.
You will need eclipse glasses or other solar filters to view all of the eclipse phases except totality.
There are fancier solar filters and glasses available at online stores like this one. This website has a ton of great information about the eclipse, and how to observe safely. Please read it, and remember that normal sunglasses are not nearly powerful enough to safely observe the Sun.
You do not need a telescope or binoculars to observe the eclipse, but if you want to use one, make sure you have a safe filter on it, or you will ruin your scope or your eyes.
What will you see?
If you do not have the option to travel to totality, you will see a partial eclipse through a solar filter. In the Peoria area, it will look something like this when it is maximally eclipsed:
It is worth watching the partial eclipse if you cannot travel to totality - it will still be an unusual and noteworthy sight. However, if you do have a chance to go to totality, you should. A partial eclipse is exciting, but a total solar eclipse is a rare phenomenon, one of the most awe-inspiring in nature.
If you travel to totality, this is what you will see:
Total Solar Eclipse in Norway, 2015. Image: Stan Honda
How can you learn more?
The Peoria Riverfront Museum's Dome Planetarium is your resource for all information about the 2017 total solar eclipse!
We will be having a planetarium show about solar eclipses starting in January, as part of the planetarium's daily public schedule.
We will have a series of lectures about the eclipse as well. They will be posted to this website and to the Facebook page.
If you have questions, feel free to contact Planetarium Curator Renae Kerrigan at firstname.lastname@example.org or 309-863-3030