On Aug. 21, millions of people in the U.S. will see day turn to night as a total solar eclipse passes over North America. The last time this happened from coast to coast was 1918. Temperatures will drop rapidly as the moon completely covers the sun. Observers will be able to see the spectacular colors and light of the sun’s atmosphere, a sight revealed only during a total solar eclipse.

The eclipse will touch the U.S. mainland for the first time since 1979, following a path that crosses the country from Salem, Oregon to Charleston, South Carolina. Tens of millions of people who live within a 70-mile radius of its cross-country track will witness the eclipse in totality (the sun completely blocked by the moon) while millions of others outside of it will enjoy a partial eclipse.

The lucky lookers will be situated in or near American cities and towns under this path, where a variety celebrations will be underway as scientists gear up and laymen prepare to peer into a universe otherwise always obscured by the sun’s rays.

An estimated two-thirds of the country lives within an easy day’s drive of the path. Top places to watch this spectacle, according to major media sources, include Salem, Ore, Madras, Ore. Richmond, Ore., Bend, Ore.,, Jefferson City, Mo, Lincoln, Neb, Nashville, Casper, Wyo., Columbia, S.C., Charleston, S.C., Jackson Hole and Grand Teton National Park, Wyo., Kansas City, Mo., St. Joseph, Mo., Carbondale, Ill.; Hopkinsville, Ky.; and the Land Between the Lakes National Recreation Area (between Kentucky and Barkley lakes in Western Kentucky and Tennessee).

Great American Eclipse by Air or by Sea

Travel companies participating in this rare event include Alaska Airlines and Royal Caribbean International.

Alaska Airlines is chasing “The Great American Eclipse” on August 21, with a special charter flight for select astronomy enthusiasts that will follow the eclipse at 35,000 feet above the earth. The flight departs Portland at 7:30 a.m. PDT and flies off the coast of Oregon, allowing guests on board to be among the first of millions to witness this phenomenon. The invitation-only flight is not commercially bookable, but Alaska Airlines is giving one lucky fan and a guest a chance to win a seat on the flight. The contest begins July 21 on Alaska Airlines’ social media channels.

Weather is the largest variable when it comes to eclipse-viewing, and the Pacific Northwest is more prone to inclement weather and overcast skies than other parts of the country. However, Alaska Airlines is making sure eclipse chasers on the West Coast have prime viewing conditions, above much of any potential weather or cloud cover.

Royal Caribbean International is celebrating on August 21 with a live musical performance by DNCE and a solar eclipse viewing party during an exclusive 7-night Total Eclipse Cruise on board Oasis of the Seas.

Adventure-seekers will have the vantage point of the century when Oasis of the Seas positions itself along the eclipse’s path of totality where the moon completely masks the sun for a few minutes of total darkness.

The viewing party will last far into the night, long after the moon eclipses the sun in what the cruise line hopes will become the high seas social media event of the century. In addition to the viewing party, passengers will be treated to other eclipse-themed activities, including dance parties, trivia, interactive science fun for kids and their families, and tasty cocktails and dishes.

Oasis of the Seas amenities include two FlowRider surf simulators and a zip line nine decks high – speeding riders 82 feet across an open-air atrium, Broadway-style shows and high-diving, acrobatic performances in the AquaTheater. Dining includes a table at 150 Central Park by James Beard Award-winning chef Michael Schwartz.

The 7-night Total Eclipse Cruise sets sail on Aug. 20, 2017 from Orlando (Port Canaveral), Florida, and visit Caribbean destinations in the Eastern Caribbean, including Phillipsburg, St. Maarten; Charlotte Amalie, St. Thomas; and Nassau. Visit: RoyalCaribbean.com/TotalEclipse.

Total Eclipse Viewing Preparations

Astronomers and solar physicists will be out in force, testing and monitoring activity along the path of the solar eclipse. They’ll use ground-based telescopes, airborne instruments, and orbiting satellites to shed new light on some of the Sun’s best-kept secrets.

When the Moon totally blocks the sun’s face for up to 2 minutes, 40 seconds, the landscape darkens suddenly, bright stars and planets shine forth in a twilight-blue sky, pastel hues of sunset glow around the horizon, the temperature drops noticeably, and birds and animals behave as if night has fallen. But the star of the show hangs in the sky where the brilliant sun used to be: the impossibly black silhouette of the Moon.

The rest of the continental U.S. will have a deep partial eclipse in which the Moon will cover half or more of the Sun’s bright face. But even a 99% partial eclipse offers almost none of the drama and beauty of a 100% total one. And another difference: the totally eclipsed Sun is about as bright as the full moon and just as safe to look at directly, even with binoculars or a telescope. But a partial solar eclipse, even a very deep one, is unsafe to look at directly without using a special-purpose solar filter, namely, one certified to meet the ISO 12312-2 international safety standard (. Such filters are commonly available in the form of cardboard- or plastic-framed “eclipse glasses” and hand-held viewers.

“Never wear eclipse glasses while looking through binoculars, a telescope, or a camera lens,” warns Angela Speck, professor of astronomy at the University of Missouri. “Sunlight focused by the optics will burn right through the filters and injure your eyes.” Speck co-chairs the AAS Solar Eclipse Task Force, which is helping to prepare the country for the event by maintaining the Solar Eclipse Across America website, which provides basic information about the eclipse, links to other authoritative resources, and safety tips developed in partnership with NASA, the American academies of ophthalmology and optometry, and the American Optometric Association. “If you don’t have a safe solar filter,” says Speck, “you can view the partially eclipsed Sun indirectly, for example, by pinhole projection as described here.”

The Exploratorium in San Francisco recently released an app called Total Solar Eclipse for iOS and Android. Through the free app, users can watch live streams with several audio options, including commentary from Exploratorium educators and NASA scientists, Spanish-language commentary, or music from the Kronos Quartet.

The Exploratorium will also show silent feeds of the eclipse from Madras, Ore., and Casper, Wyo. Madras will get about two minutes of totality starting at 10:19 a.m. PDT, and Casper will provide a slightly longer dose starting at 10:42 a.m. PDT.