Counting Down to the Solar Eclipse on August 21
On Aug. 21, 2017, everyone in North America will have the chance to see a solar eclipse if skies are clear. We’re giving you a preview of what you’ll see, how to watch and why scientists are particularly excited for this eclipse.
On Aug. 21, within a narrow band stretching from Oregon to South Carolina – called the path of totality – the Moon will completely obscure the Sun, giving people on the ground a view of the total solar eclipse. Outside this path – throughout North America, and even in parts of South America – the Moon will block only a portion of the Sun’s face, creating a partial solar eclipse.
Image credit: T. Ruen
Eclipses happen when the Moon, Sun and Earth line up just right, allowing the Moon to cast its shadow on Earth. Because the Moon’s orbit is tilted with respect to the Sun-Earth plane, its shadow usually passes above or below Earth. But when they all line up and that shadow falls on Earth, we get a solar eclipse.
How to Watch the Eclipse Safely
It’s never safe to look directly at the un-eclipsed or partially eclipsed Sun – so you’ll need special solar viewing glasses or an indirect viewing method, like pinhole projection, to watch at the eclipse.
If you’re using solar viewing glasses or a handheld solar filter, there are a few important safety tips to keep in mind:
- Check a few key characteristics to make sure that you have proper solar filters – sunglasses (even very dark ones) or homemade filters are NOT safe
- Double-check that your solar filter is not scratched or damaged before you use it
- Always put your solar filter over your eyes before looking up at the Sun, and look away from the Sun before removing it
- Do NOT use your solar filter while looking through telescopes, binoculars, or any other optical device, such as a camera viewfinder – the concentrated solar rays will damage the filter and enter your eyes, causing serious injury
Get all the details on safety at eclipse2017.nasa.gov/safety.
No solar viewing glasses? Pinhole projection is an easy and safe way to watch the eclipse. You can create a pinhole projector from a box, or simply use any object with tiny holes – like a colander or a piece of cardstock with a hole – to project an image of the Sun onto the ground or a piece of paper.
If you are in the path of totality, there will come a time when the Moon completely obscures the Sun’s bright face. This is called totality, and it is only during this phase – which may last only a few seconds, depending on your location – that it is safe to look directly at the eclipse.
Wherever you are, you can tune into nasa.gov/eclipselive throughout the day on Aug. 21 to hear from our experts and see the eclipse like never before – including views from our spacecraft, aircraft, and more than 50 high-altitude balloons.
A Unique Chance for Scientists
Total solar eclipses provide a unique opportunity to study the Sun and Earth. During a total eclipse, the lower parts of the Sun’s atmosphere, or corona, can be seen in a way that cannot completely be replicated by current human-made instruments.
The lower part of the corona is key to understanding many processes on the Sun, including why the Sun’s atmosphere is so much hotter than its surface and the origins of the Sun’s constant stream of solar material and radiation – which can cause changes in the nature of space and impact spacecraft, communications systems, and orbiting astronauts.
Photo credit: S. Habbal, M. Druckmüller and P. Aniol
For those in the path of totality, the few moments of the total solar eclipse will reveal the Sun’s atmosphere, the corona.
Total solar eclipses are also a chance to study Earth under uncommon conditions: In contrast to the global change in light that occurs every day at dusk and dawn, a solar eclipse changes illumination of Earth and its atmosphere only under a comparatively small region of the Moon’s shadow. This localized blocking of solar energy is useful in evaluating our understanding of the Sun’s effects – temperature, for example – on our atmosphere. Of particular interest is the impact on Earth’s upper atmosphere, where solar illumination is primarily responsible for the generation of a layer of charged particles called the ionosphere.
We’re also inviting eclipse viewers around the country to become citizen scientists and participate in a nationwide science experiment by collecting cloud and air temperature data and reporting it via the GLOBE Observer smartphone app.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com