On August 21, 2017, nature's greatest spectacle -- a total solar eclipse -- will make an America-only appearance from sea to shining sea!
Engineer 3D! Conference attendees received GSC Eclipse Glasses, which can be used to safely view the sun any time of year. On days where there is a lot of solar activity, you may be able to see magnetic storms produce cooler areas on the surface of the sun, which results in visible dark areas called sunspots.
On the day of the eclipse, you can use your GSC Eclipse Glasses to track the moon as it progressively blots out more and more of the sun; this is the partial eclipse phase of the event. If you're outside the path of totality, you will see the moon's encroachment on the sun reach a certain percentage, and then it will begin to leave the area as the moon progresses in its orbit.
If, however, you are inside the path of totality, you will eventually see the moon completely blot out the sun, and the view through your GSC Eclipse Glasses will go black. That's because there isn't enough light from the now-visible solar corona and prominences to penetrate the filters; when totality strikes, it's time to take off the glasses and experience nature's most awesome spectacle. Depending on where you are along the path of totality (and how close to the centerline you are), totality for this eclipse will last a maximum of 2 minutes 40 seconds. As soon as the first instant of sunlight appears at the end of totality, immediately look away and use your GSC Eclipse Glasses to safely watch the second partial eclipse phase as the moon moves away from the sun completely.
If you want to plan a trip to totality (and I sincerely hope you do), you will need a planning tool. The best one I know of is a "web app" from the good folks at GreatAmericanEcplise.com: Eclipse Web App. Their main website has a lot of good information about the 2017 total solar eclipse, as well. If you want to see what NASA has in store for the eclipse, head over to their dedicated eclipse website.