A very rare astronomical event is coming in 2017. The United States will be experiencing a total solar eclipse on August 21, 2017. To see the sky darkened by a total solar eclipse in the midwestern U.S., you had to be alive in 1919!
A solar eclipse occurs when the moon “appears” to cover up the sun. What is really happening is the moon passes between Earth and the sun, and the moon casts a shadow on Earth. As the Earth and the Moon continue to move relative to the Sun, the area of the total eclipse moves across the surface of the Earth. Thus the eclipse can be seen at different times from different parts of the world.
Since the moon is so small, the geometry of a total solar eclipse has to be just right. Only a very small portion of Earth’s surface gets the total solar eclipse experience. To see the greatest effect, you have to be in direct line with the umbra, the darkest effect where all sunlight is blocked out by the moon (yellow portion in the diagram above). This is a very small area. The penumbra, (purple area in the diagram) is a partial shadow where some, but not all, of the sun’s light is blocked. This area is much larger across Earth’s surface. Thus, most people will only experience a partial solar eclipse in their lifetime. That’s what makes this upcoming eclipse such a rare occurrence. While a total solar eclipse happens somewhere on our planet roughly once every 18 months, the last one to be in the continental United States was in 1979. Seeing one anywhere near Illinois has happened only three times in the last century.
The far southern portion of the state is the only part that sees totality, but it gets a lot! To help you plan for this historic event, Southern Illinois University, NASA and many other organizations have put together some informative webpages about Eclipse 2017. Here are just a few:
Many people are already reserving accommodations in the southern tip of Illinois, so plan accordingly! As the Chicago Tribune reports, motels and hotels in these many small towns will soon be filling up!
PLEASE NOTE: It is never safe to look directly at the sun – this can damage your eyes, even during an eclipse. Even sunglasses cannot protect your eyes from the damage the Sun’s rays can do to them.
If you can’t make it to the path of totality, the next-best place to be on August 21, 2017 is the Adler Planetarium. They will be having special events and educational programs so be sure to check their website as we get closer to the event.