The Great American Eclipse of 2017

I was in 8th grade when I first learned about the Great American Eclipse. Mr. Pearsall, the science teacher at Washington Middle School, gave us a handout on the eclipse and told us not to miss it. 11 years later, I live 25 miles from the path of totality, and I wouldn’t miss this eclipse for the world! I hope Mr. Pearsall is able to see this eclipse as well.

The Great American Eclipse is the first eclipse since 1918 to transverse the entire Continental US and the first since 1979 to hit any part of the continental US. The next total solar eclipse to hit the US will be in 2024, and you’ll have to wait until 2045 for the next total solar eclipse spanning the entire Continental U.S.

How Solar Eclipses Occur:

A solar eclipse occurs when a new moon is directly between the sun and the Earth. Because the moon’s orbit is tilted 5 degrees relative to the Earth’s orbit around the sun (also known as the ecliptic), the moon is usually slightly above or below the Earth. As such, when there is a new moon, the shadow it casts usually misses the Earth.

But there are two “nodes” at which the moon lies on the ecliptic and is therefore in the same plane as the sun and Earth. If the moon is new during this phase, you get a solar eclipse! Conversely, if it is full, you get a lunar eclipse.

The Different Types of Eclipses:

When light from the sun impacts the moon, it casts a shadow with three distinct parts – the umbra, penumbra, and antumbra. These correspond (in order) to the three types of solar eclipses: total, partial, and annular.

To understand how the umbra, penumbra, and antumbra work, we must recognize that the sun is a disc and not a “point” source of light, like the twinkling stars in the night sky. A disc source emits light from multiple points, while a point source emits from a single point.

Because the sun is a disc source of light, light originates from different angles when it encounters an object like the moon. In the umbra, the moon completely obscures light coming from all angles, while light is only obscured from some angles in the penumbra. The antumbra is directly behind the umbra, and in the case of an eclipse, it means the moon is too far away from the Earth for the umbra to reach the Earth’s surface (the moon’s orbit around the earth is elliptical, and it is closer at some points than others).

Since the moon and sun are approximately the same size (as viewed from Earth… not in reality!), the umbra is extremely small for a total solar eclipse and the vast majority of eclipsed areas see a partial eclipse.

What To Expect During The Eclipse:

The period of totality will be brief – between 1 and 2 minutes for most in the Pacific Northwest. However, we’ll spend approximately 90 minutes in the penumbra before and after the total eclipse. Expect the sky to get progressively darker during this time, and be on the lookout for eerie crescent-shaped shadows filtering through trees!

As the sky gets darker, expect the brightest planets/stars to make an appearance. At totality, the sun’s corona will be approximately as bright as a full moon, meaning many stars will be visible, particularly if you are away from any light pollution.

Temperatures will drop as we approach totality, and birds may even stop chirping! I’m interested to see how wildlife responds to an unexpected transition from day to night and back again.

How To Watch The Eclipse:

The path of totality will travel ESE across Northern Oregon, making landfall near Lincoln City just before 10:16 AM and crossing the Idaho border around 10:26 AM.

Because this eclipse will occur in the morning, there is a significant change that a morning marine layer west of the Cascades could obscure the eclipse, especially along the coast. I’ll be staying at my uncle’s place in Pacific City, so I’m praying to the weather gods for clear skies on the morning of the 21st. From a meteorological perspective, Eastern Oregon near Madras is your best bet for viewing the eclipse, but I’ve heard that there could be an influx of 100,000 people into this sleepy town of 6,351, so leave yourself plenty of time to get there and don’t expect to find any vacant hotels!

And the most important thing:

If you plan to view the eclipse, you MUST wear eye protection for all phases except totality. Even looking directly into a nearly-eclipsed sun can cause permanent eye damage. Solar eclipse glasses are easy to find – you can order them online or find them at a grocery store. Regular sunglasses will NOT work, as they do not block out harmful UV rays.

Thanks for reading, and I hope you are as excited for the solar eclipse as I am! I’ll definitely post forecast updates as the eclipse approaches.

Have a nice day,
Charlie