This Simulator Shows What You'll See During the Great American Solar Eclipse

The Eclipse Megamovie 2017 project aims to gather images from volunteer photographers and astronomers, and offers a handy tool to forecast the eclipse view in different locations.

Where will you be when the total solar eclipse is visible from the continental United States on August 21? If you’re debating between different spots, a handy “eclipse simulator” will help you forecast the degree of the eclipse that will be seen in a particular location.

(A word of warning – follow NASA’s safety tips before doing any eclipse observations with your eyes, binoculars, or a telescope. Never look directly at the sun without protective equipment.)

Solar eclipses – from Earth’s perspective, at least – occur when the moon passes in between the sun and the Earth. If the moon covers only a part of the sun, it’s called a “partial” solar eclipse and if it covers the entire sun, it is a “total” solar eclipse.

A total eclipse is by far the most spectacular experience. The sky grows dark, the corona (or sun’s atmosphere) peeks out from around the moon, and sometimes singing birds fall quiet because they think that nighttime has suddenly arrived. But only a very narrow band of cities along a path that cuts diagonally through the United States will experience totality. The moon’s shadow is small, so you have to be in just the right spot.

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That’s where the eclipse simulator on the Eclipse Megamovie 2017 website comes in. Say you’re in Oregon deliberating between different locations. Type in “Portland” and press play, and you’ll see that the doesn’t quite obscure all of the sun’s disc. If you want to see totality, you’ll have to go elsewhere.

Referring to the total eclipse map for nearby cities, you’ll see that nearby Salem is in the path of totality. And if you look again on the simulator – this time typing in “Salem, Oregon” into the bar – you’re rewarded with a dark sky as the sun gets completely obscured by the moon.

A map of the United States showing the path of totality for the August 21, 2017 total solar eclipse. | NASA

While the total eclipse will only last a few minutes, the “megamovie” will let people remember it forever. The project aims to gather images from more than 1,000 volunteer photographers and amateur astronomers. From there, the forthcoming movie will have an “expanded and continuous view” of the eclipse as it moves from coast to coast.

“Of particular interest to our team are the moments when the sun is almost totally eclipsed and again when it is just coming out of total eclipse, when observers can view something called ‘the diamond ring effect,’ ” says the project’s website.

“More light from the sun can be seen at this time through a single valley on one side of the moon,” it goes on. “This produces a flash of light that joins the fainter light from the corona that surrounds the moon, thus creating something that looks like an enormous diamond ring — similar to what someone might wear on their finger. We will be able to study this effect and how it changes with time, which may also allow us to measure the size of the sun with better precision.”

Even if you can’t join in the eclipse fun in person, there will be live coverage from NASA TV, Slooh, and many other astronomy websites. You can download interactive maps and other information from NASA’s official eclipse website.