BOULDER CITY, Nevada – America’s national parks will be premier viewing sites for a rare solar eclipse that will be crossing the United States Aug. 21. Lake Mead National Recreation Area is holding a free viewing party at the visitor center from 9 a.m. to noon.

The 2017 eclipse is the first total solar eclipse visible in the continental United States since Feb. 26, 1979. Prior to that, the last eclipse to traverse from coast to coast was June 8, 1918.

August 21, the moon’s shadow will race across the land, crossing from the Oregon coast to the point where South Carolina meets the Atlantic Ocean in just one and a half hours. Throughout the continental United States, people outside the path of totality will witness a partial eclipse, as the shadow of the moon covers or eclipses some portion of the sun.

At Lake Mead, 71 percent of the sun will be eclipsed. The eclipse will begin at 9:09 a.m. and end at 11:53 a.m. with a peak at 10:28 a.m.

During the eclipse, natural sunlight will be disrupted as the moon moves directly between the sun and Earth, casting its shadow on the ground below. Visitors can safely view the eclipse with rangers at the Lake Mead Visitor Center using a solar telescope and solar glasses.

The National Park Service is encouraging visitors to prepare to have a safe viewing opportunity during the eclipse. Looking at the sun directly, even just the sliver of sun visible before the total eclipse, can cause permanent eye damage. Homemade sun filters and regular sunglasses do not provide sufficient eye protection.

To view the sun during the eclipse, use eclipse glasses or a handheld solar viewer. The American Astronomical Society, a NASA partner, has verified that these manufacturers are making eclipse glasses and handheld solar viewers that meet the ISO 12312-2 international standard for such products. In addition to making sure that eclipse shades or handheld viewers meet the ISO safety standard, make sure they’re in good condition. If the filters are torn, scratched, punctured, or coming loose from their cardboard or plastic frames, discard them.

Do not look at the sun through a camera lens, telescope, binoculars or other optical device without a specially designed filter. The sun can damage the camera sensor and harm your eyes. A pinhole projector is another safe, inexpensive way to view the eclipse safely.

For more information about the eclipse and for interactive maps, visit https://eclipse2017.nasa.gov. For more information about the viewing party, call 702-293-8990.

The next solar eclipse visible from the continental United States will be April 8, 2024.