Millions of Americans are looking to the skies for the country's first total solar eclipse in nearly 100 years.
The Moon will pass between Earth and the Sun, temporarily blocking the sun.
The so-called 'path of totality' will touch 14 states across the entire width of the US, while at least a partial eclipse will be visible from everywhere in the country.
The once-in-a-lifetime phenomenon will be the most far-reaching to have been seen in the US since 1918, and the first time a total solar eclipse will have been visible from anywhere on mainland US since 1979.
A number of special events are being organised to mark the occasion - including Bonnie Tyler performing her hit Total Eclipse of the Heart on Royal Caribbean's Total Eclipse Cruise as the eclipse takes place.
Although those in the US will be the only ones to see the total eclipse, a number of other areas around the world - including Ireland - will experience a partial solar eclipse this evening.
Although the exact times vary across the country, the partial eclipse will begin at around 7.30pm, and will peak in most areas at around 8pm.
Astronomy Ireland - which is holding viewing sessions in Dublin & Waterford, as well as leading a trip to the US - is warning people to not look directly at the sun during the event.
They explain: "The Sun should never be viewed directly as this will result in serious eye injury and even total loss of vision which is permanent. The safe ways to view are indirect - i.e. the traditional projection of an image of Sun onto a bright surface or by using only approved astro solar filters on telescopes and binoculars. The filters should be carefully inspected for even pinhole damage.
"Great care should be exercised if using approved eclipse glasses [...] and never use sunglasses or other homemade filters."
Irish astronomers will, unfortunately, have to wait quite a while for their own total eclipse of the sun - the next one will not take place here until 2090.