It's the most spectacular sight in nature and there hasn't been one on Irish soil since 1727 nor will there be one until 2090.
It's a Total Eclipse of the Sun and there will be a Partial Eclipse of the Sun over Ireland on August 21st.
To celebrate this event, Astronomy Ireland are holding an Eclipse Watch in Waterford.
It will take place from 7:30pm-8:30pm at Kingsmeadow, Old Cork Road, Waterford.
Eclipses occur when the Moon partially or totally blocks out the Sun for 2 - 3 minutes but the path of totality is narrow.
A partial eclipse can be seen over a much wider but ever diminishing path within the penumbra or shadow of the Moon.
It only happens because the Sun's diameter is 400 times that of the Moon and distance of the Sun from the Earth is also 400 times that of the Moon making them appear the same size on Earth.
As the Moon's orbit around Earth is tilted at about 5 degrees and not perfectly circular total eclipses are occasional rather than monthly occurrences.
The last eclipse over the mainland United States was in 1979 and the path of totality only crossed 5 states. The next will occur in April 2024 (12 States) and again in 2045 (10 States).
The Great American Eclipse as it is now being called is the first total eclipse to cross the contiguous United States since June 8, 1918 and will cross fourteen states from Oregon to South Carolina from just after 5.00 p.m. (Irish Summer Time) to just after 9.00p.m. The corridor of totality will be a narrow band 110 Km (70 miles) wide extending Southeast from Oregon to South Carolina.
It will be visible from beginning to end only in Ireland until sunset.
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 (which are available by phoning Astronomy Ireland H.Q.) and never use sunglasses or other homemade filters.