The "Great American Solar Eclipse" is on its way and skygazers across the country are already in countdown mode, planning celebratory events in anticipation of a phenomenal astronomical event, the likes of which haven't been seen since the 1970s. The upcoming celestial rarity will occur on Aug. 21, 2017.

A solar eclipse occurs when the moon passes directly between the earth and sun, and as a result obscures the sun entirely, though briefly. Essentially, the moon blocks all direct sunlight and turns day into a brief darkness, or "night."

The upcoming 2017 phenomena will be the first solar eclipse to cross the entire U.S. of A in 99 years. However, not since the 1970s has there been an opportunity to see a total solar eclipse in such a widespread area of the country, and in locations that are so easily accessible, USA Today reports.

According to NASA, the path of this eclipse will begin in the northern Pacific and cross the United States from west to east, in a path that will pass through the following states: Oregon, Idaho, Montana, Wyoming, Nebraska, Kansas, Maryland, Missouri, Illinois, Kentucky, Tennessee, North Carolina, Georgia, and South Carolina.

A website created by eclipse enthusiasts has mapped out "eclipse information for every city and town in the path." Including literally every single location in the U.S. where the eclipse will be visible, curious viewers can access that information here.

Space.com describes the experience of viewing a total solar eclipse in the following engaging narrative:

"Picture this: The day starts off bright and sunny. Then, a bit later, you begin to notice that, although it is still sunny, the day doesn't seem quite so bright. And still a little while later, it almost seems like some big storm is brewing. Then, suddenly, and without any warning, the midsummer day turns strangely dark.

A few stars come out. Birds and animals become confused and quickly head home to sleep. Night insects begin to chirp. All around the horizon, there is a strange yellow-orange glow resembling a weird sunset. And meanwhile, up in the sky where the sun should be, there appears instead a jet-black disk surrounded by a softly glowing halo.

Then, just as suddenly, the sky brights up. The stars disappear, birds and animals awaken, and the sun returns.

What you have just witnessed is a total eclipse of the sun."

Viewing a full full solar eclipse in its totality is something that happens very quickly and the duration of the event is always longest along the path of the moon's shadow.

Beginning with the coastline of Oregon, totality of the event will last for just under two minutes. As the moon's shadow heads southeast along its projected path of viewing, totality will lengthen to approximately two minutes and 40 seconds as it passes through southern Illinois. Continuing to traverse the country, totality decreases to two minutes and 34 seconds along the coastline of South Carolina, before heading out to sea and beyond America's field of vision.

Major cities that fall within the totality path include: Idaho Falls, Idaho; Casper, Wyoming; Lincoln, Nebraska; Columbia, Missouri; Nashville, Tennessee; Columbia, South Carolina; and Charleston, South Carolina.

For those lucky enough to witness this upcoming event, it's crucial to note that in order to view the eclipse as it happens you must purchase a special pair of glasses (available at many online retailers) in order to avoid permanent damage to the retina, or even blindness that can occur from staring straight at the sun (even when eclipsed).

Using binoculars or a telescope are just as hazardous as viewing through the naked eye, so be sure to stock up on these special eclipse viewing glasses for yourself and those joining your viewing party. Enjoy the show!